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ISBN978-1-118-94847-7(paperback);ISBN978-1-118-94846-0(ePub);978-1-118-94845-3(ePDF)

Toeverystudentevertoldtheyhadtochoosebetweentheartsandsciences.

AbouttheAuthorBECKYSTEWARTisanengineerandeducator.Sheworkswithartistsanddesignerstobringtolifeoftencrazyideas—fromshoesthatshowyouhowtogethometosuspensionbridgesthatcanbeplayedlikegiantharps.AftercompletingaPhDinElectronicEngineeringatQueenMaryUniversityofLondon,BeckyhelpedfoundCodasign,aneducationcompanythatcreatestechnologyworkshopsforartgalleriesandmuseums.AtCodasignsheteachesartistsanddesignershowtouseelectronicsandcodeascreativetools.Shedocumentsherprojectsathttp://theleadingzero.com.

AcknowledgmentsMyfirstthanksgotoAlexandraDeschamps-Sonsino,withoutwhomIwouldhaveneverstartedthisbook.IalsooffermysinceregratitudetoAlexforherworkwithTinkerthatjumpstartedtheArduinocommunityinLondon.

NoneofthiswouldhavebeenpossiblewithoutthesupportoftheamazingeducatorsthatformCodasign.IhavelearnedmuchfromMelissaColemanandPollieBardenabouthowtoimprovemyArduinoteaching,andIamconstantlylearningfromAdamStarkabouthowtobetterteachprogrammingconcepts.Ican’tstopthankingEmilieGiles—Codasignwouldgrindtoahaltwithoutyou;thankyouforeverythingyoudo.Igiveaparticularlyhugethank-youtoLiatWassershtromforallyourfeedbackandexpertise.

I’dliketoalsothanktheartisticandeditorialstaffthathelpedshapethisbook.Ithasbeengreatlyimprovedbyyourguidance.

Lastly,thankyoutomyfamilywhohavesupportedmeineverythingIdo.Thankyoutomyparents,whoprovidedaquietplacetositandwrite,andtoBen,whohaspatientlytoleratedourweddingplanningandvacationsbeingpunctuatedbywriting.

Publisher’sAcknowledgementsSomeofthepeoplewhohelpedbringthisbooktomarketincludethefollowing:

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AdventuresinArduino®

Contents

CoverTitlePageAbouttheAuthorIntroduction

WhatIsanArduino?WhatYouWillLearnPartsYouWillNeedToolsYouWillNeedSoftwareYouWillNeedOtherUsefulMaterialsWhatIAssumeYouAlreadyKnowHowThisBookIsOrganisedConventionsTheCompanionWebsiteReachingOut

Adventure1:SettingUpYourArduinoWhatYouNeedDownloadingandInstallingtheArduinoSoftwareonYourComputerUsingBlinktoTestThatEverythingIsSetUpCorrectlyBuildinganLEDCircuitFurtherAdventureswithArduino

Adventure2:ReadingfromSensorsWhatYouNeedAddingMoreLEDsPrintingMessagestotheComputerReadingDatafromaPotentiometerMakingDecisionsinCodeBuildingaStatusMessageSignFurtherAdventureswithArduino

Adventure3:WorkingwithServosWhatYouNeed

UnderstandingDifferentTypesofMotorsControllingaServowithArduinoRepeatingtheSameThingOverandOverDigitalInputwithaPushButtonBuildingaCombinationSafeFurtherAdventureswithArduino

Adventure4:UsingShiftRegistersWhatYouNeedOrganisingYourCodeGettingMoreOutputswithShiftRegistersBuildingYourNameinLightsFurtherAdventureswithShiftRegisters

Adventure5:PlayingSoundsWhatYouNeedMakingaListMakingNoiseBuildinganAugmentedWindChimeFurtherAdventureswithSound

Adventure6:AddingLibrariesWhatYouNeedAnalogueOutCapacitiveSensingBuildingaCrystalBallFurtherAdventureswithLibraries

Adventure7:WorkingwiththeArduinoLeonardoWhatYouNeedIntroducingtheArduinoLeonardoSensingLightBuildingaGameControllerFurtherAdventureswiththeLeonardo

Adventure8:WorkingwiththeLilypadArduinoUSBWhatYouNeedIntroducingtheLilypadArduinoUSBGettingCleverwithArraysPassingDataBetweenFunctionsBuildingaPOVHoodie

FurtherAdventureswiththeLilypadAdventure9:TheBigAdventure:BuildingaMarbleMazeGame

WhatYouNeedPartOne:ScoringPointsPartTwo:DesigningYourMazeGamePartThree:WritingtheCodePartFour:BuildingtheMazeGameFurtherAdventures:ContinuingYourAdventureswithArduino

AdventureA:WheretoGoFromHereMoreBoards,Shields,SensorsandActuatorsOntheWebBooks

AdventureB:WheretoGetToolsandComponentsStarterKitsBrick-and-MortarStoresOnlineStores

GlossaryEndUserLicenseAgreement

ListofIllustrations

IntroductionFIGUREI-1ArduinoUno(topleft),ArduinoLeonardo(bottomleft)andLilypadArduinoUSB(right)FIGUREI-2AUSBandUSBMicrocableFIGUREI-3BreadboardsindifferentsizesandcoloursFIGUREI-4JumperwiresFIGUREI-5DifferenttypesofLED,withacolour-changingLEDontherightandbelowitaLilypadLEDFIGUREI-6Resistorsneededfortheprojectsinthisbook:100Ω(topleft),220Ω(topright),10kΩ(bottomleft),1MΩ(bottommiddle)and10MΩ(bottomright)FIGUREI-7ThreedifferenttypesofpotentiometerFIGUREI-8AservomotorFIGUREI-9Atactilepushbutton(left)andthreedifferentpanelmountbuttons(right)FIGUREI-10AshiftregisterFIGUREI-11ApiezoFIGUREI-12Alight-dependentresistorFIGUREI-13MaleheaderpinsFIGUREI-14Solidcorewire(left)andstrandedwire(right)FIGUREI-15Enamelled(left)andplasticcoated(right)wireFIGUREI-16SolderonspoolsFIGUREI-17A9Vbattery-to-DC-barrelconnector(left)andaUKplugforaUSBcable(right)FIGUREI-18AlligatorclipsFIGUREI-19ConductivethreadFIGUREI-20AsolderingironFIGUREI-21DifferentkindsofwirestripperFIGUREI-22WirecuttersFIGUREI-23PairsofpliersFIGUREI-24AmultimeterFIGUREI-25Apairofscissorsandautilityknife

Chapter1FIGURE1-1AnArduinoUnoandUSBcableFIGURE1-2YoucandownloadtheArduinoIDEforyourcomputerfromthe

Arduinowebsite.FIGURE1-3PlugtheUSBcableintotheArduinoUnoandthenconnectittoyourcomputer.FIGURE1-4TheArduinoprogramiconFIGURE1-5TheimportantpartsoftheArduinoIDEFIGURE1-6Thebuilt-inLEDontheArduinoboardisnearthenumber13.FIGURE1-7OpeningtheBlinksketch,whichislocatedintheexamplesthatareincludedwiththeArduinoIDEFIGURE1-8SelectingtheboardyouareusingFIGURE1-9SelectingtheportyourArduinoboardispluggedintoFIGURE1-10MessageintheArduinoIDEaftersuccessfullyuploadingyourcodeFIGURE1-11Acommonerrorwhenthecomputercan’ttalkwiththeArduinoFIGURE1-12TheelectroniccomponentsyouneedtobuildthecircuitFIGURE1-13ThecircuitschematicfortheLEDcircuitFIGURE1-14Abreadboardhasaseriesofholesthatareconnectedinrowswithtwopairsoflongrowsontheoutsideandshorter,perpendicularrowsinthecentreoftheboard.FIGURE1-15BasiclayoutofabreadboardFIGURE1-16TheLEDcircuitonthebreadboardFIGURE1-17ThedigitalpinsontheArduinoboard.DigitalPins0and1arespecialpinsthatyoulearnaboutlater.

Chapter2FIGURE2-1TheelectroniccomponentsyouneedforthefirstpartofthisadventureFIGURE2-2BuildingacircuittocontrolthreeLEDsFIGURE2-3TheSerialMonitorbuttonFIGURE2-4TheSerialMonitorintheArduinoIDEFIGURE2-5DifferentpotentiometersFIGURE2-6AnaloguepinsontheArduinoUnoFIGURE2-7CircuitforconnectingapotentiometerFIGURE2-8AstatusmessagesignFIGURE2-9TheelectroniccomponentsyouneedtomakeastatusmessagesignFIGURE2-10CircuitschematicforthesignFIGURE2-11PrototypecircuitonthebreadboardforthesignFIGURE2-12CuttingholesfortheLEDsandknobFIGURE2-13TheLEDportionofthecircuit

FIGURE2-14SolderedpotentiometerFIGURE2-15PowersupplythatyoucanusewithanArduinoboardFIGURE2-16Completedstatusmessagesign

Chapter3FIGURE3-1TheelectroniccomponentsyouneedforthefirstpartofChapter3FIGURE3-2AservomotorandtoyDCmotorFIGURE3-3OpeningtheSweepexamplesketchFIGURE3-4CircuittoconnectaservototheArduinoboardFIGURE3-5HowatactilepushbuttonworksFIGURE3-6CircuitwithatactilepushbuttonFIGURE3-7Circuitwithapull-upresistorFIGURE3-8Circuitwithapushbuttonandinternalpull-upresistorontheArduinoboardFIGURE3-9CombinationsafeFIGURE3-10TheelectroniccomponentsyouneedtobuildyourcombinationsafeFIGURE3-11CircuitschematicforthecombinationsafeFIGURE3-12CircuitforthecombinationsafeFIGURE3-13Ifthelidisnotalreadyattachedtoyourbox,addapaperhinge.FIGURE3-14Extendtheservo’sarmbyattachinganobjectlikeapapercliporbambooskewer.FIGURE3-15PaperloopsotheservocanclosethesafeFIGURE3-16SolderedcomponentsFIGURE3-17Completedcombinationsafe

Chapter4FIGURE4-1WhatyouneedforthefirstpartofthisadventureFIGURE4-2TheanatomyofafunctionFIGURE4-3TheanatomyofaforloopFIGURE4-4TheCLOCKsignalFIGURE4-5HowashiftregisterworksFIGURE4-6Pin-outdiagramfortheshiftregisterFIGURE4-7FirstconnectionsfortheshiftregisterFIGURE4-8ThefullcircuitfortheshiftregisterFIGURE4-9HowtoconvertfromabinarynumbertoadecimalnumberFIGURE4-10Howwouldthisbinarypatternberepresentedbyadecimalnumber?FIGURE4-11Addingasecondshiftregister

FIGURE4-12Yourname(oranyotherword)inlights!FIGURE4-13TheelectroniccomponentsyouneedtobuildyournameinlightsFIGURE4-14CircuitschematicforthreeshiftregistersFIGURE4-16CardboardletterswithholesforLEDsFIGURE4-17SolderedLEDsandresistorsFIGURE4-18Backoflights

Chapter5FIGURE5-1TheelectroniccomponentsyouneedforthefirstpartofthisadventureFIGURE5-2TwoexamplearraysFIGURE5-3ThecircuitforanarrayofLEDsFIGURE5-4HowsoundismadeFIGURE5-5ThecircuitforausingapiezoasaspeakerFIGURE5-6AnaugmentedwindchimeFIGURE5-7TheelectroniccomponentsyouneedtomakethewindchimeFIGURE5-8CircuitschematicfortheaugmentedwindchimeFIGURE5-9BreadboardprototypecircuitFIGURE5-10ConductivitytestFIGURE5-11AchimeFigure5-12AchimeattachedtothebaseFIGURE5-13Topofbase

Chapter6FIGURE6-1TheelectroniccomponentsyouneedforthefirstpartofthisadventureFIGURE6-2AnalogueanddigitalsignalsFIGURE6-3ThepinsthatsupportanalogWrite()FIGURE6-4LEDcircuitforfadinganLEDFIGURE6-5PulsewidthmodulationexamplesFIGURE6-6RGBLEDsFIGURE6-7CircuitconnectinganRGBLEDtoanArduinoboardFIGURE6-8MixinglightversusmixingpaintFIGURE6-9PlacethedownloadedandunzippedfolderinthelibrariesfolderoftheArduinosketchbook.FIGURE6-10Checkforthelibraryandexampleinthemenus.FIGURE6-11CapacitivesensingcircuitFIGURE6-12Atouch-sensitivecrystalballFIGURE6-13Theelectroniccomponentsyouneedtomakethecrystalball

FIGURE6-14CircuitschematicforthecrystalballFIGURE6-15BreadboardprototypecircuitFIGURE6-16MappingavaluetoanewrangeFIGURE6-17PapiermachécrystalballFIGURE6-18Aluminiumfoil–coveredbaseFIGURE6-19SolderedLEDcircuitFIGURE6-20SolderedsensorcircuitFIGURE6-21Completedcrystalballcircuit

Chapter7FIGURE7-1TheelectroniccomponentsyouneedforthefirstpartofthisadventureFIGURE7-2SelectingtheArduinoLeonardofromTools⇒BoardintheArduinoIDEFIGURE7-3USBconnectorsFIGURE7-4TheLeonardotypinginawordprocessingprogramFIGURE7-5AnalogueanddigitalsignalsFIGURE7-6Ohm’sLawdefineshowvoltage,currentandresistancearerelated.FIGURE7-7Twovoltagedividercircuits,onewithanLDRasthetopresistanceandtheotherwithanLDRasthebottomresistanceFIGURE7-8TheequationtocalculatehowdifferentresistorvaluesinavoltagedividerchangetheoutputvoltageFIGURE7-9ArduinoLeonardogamecontrollerFIGURE7-10TheelectroniccomponentsyouneedtomakethegamecontrollerFIGURE7-11CircuitschematicforthegamecontrollerFIGURE7-12ThegamecontrollercircuitFIGURE7-13Coverwithoutanycircuitry

Chapter8FIGURE8-1TheelectroniccomponentsyouneedforthefirstpartofthisadventureFIGURE8-2TheLilypadArduinoUSBFIGURE8-3AnFTDIprogrammingboard,whichyouneedifyouareusingatypeofLilypadArduinootherthanaLilypadArduinoUSBFIGURE8-4TheArduinoLilypadArduinoUSBONswitchFIGURE8-5SelectLilypadArduinoUSBfromthelistofboardsFIGURE8-6Insteadofjumperwirestoconnectcomponents,usealligatorclipswhenprototypingsoftcircuits.FIGURE8-7LilypadLEDsaresewableLEDsthatalreadyhavecurrent-limitingresistors.

FIGURE8-8Alistofintegers,alsocalledaone-dimensionalarrayFIGURE8-9Atwo-dimensionalarrayofintegersstoredinrowsandcolumnsFIGURE8-10CircuitforanarrayofLEDsFIGURE8-11Iteratingoverframesofananimationstoredinatwo-dimensionalarrayFIGURE8-12Persistence-of-visionhoodieFIGURE8-13TheelectroniccomponentsyouneedforthePOVhoodieFIGURE8-14CircuitschematicforthePOVhoodieFIGURE8-15PrototypingthecircuitwithalligatorclipsFIGURE8-16Persistenceofvisionmessagecapturedwithalong-exposurephotographFIGURE8-17BendingthelegsofcomponentstomakethemsewableFIGURE8-18FirstconnectionsforsewingtheLilypadcircuitFIGURE8-19ContinuingtosewtheLEDsintothecircuitFIGURE8-20ThesewnPOVcircuit

Chapter9FIGURE9-1AcompletedbigadventuremarblemazegameFIGURE9-2TheelectroniccomponentsyouneedtobuildyourmazegameFIGURE9-3CircuittouseapiezoasasensorFIGURE9-4CircuitforfivepiezosassensorsandonepiezoasaspeakerFIGURE9-5GuidelinesfordesigningyourmazeFIGURE9-6HowthecodeworkswhenagameisplayedFIGURE9-7CircuitschematicofthemazegameFIGURE9-8MazegameprototypecircuitonabreadboardFIGURE9-9Howaloop()worksFIGURE9-0Gluestripsofcardtoguidethemarbleafteritdropsthroughahole.FIGURE9-1LidofthemazegamefittedtobottomFIGURE9-3WiringlayoutforpiezosFIGURE9-4SolderthenegativelegsoftheLEDsandonecontactofthebuttontogether.

IntroductionAREYOUANadventurer?Doyouboldlyembarkonnewendeavours,tacklingnewskillsandmasteringnewtools?Doyouwanttolearnhowtousetechnologytomakeyourideasburstintolife?Areyoucuriousabouthowyoucancombinecomputercodeandelectricalcircuitswithscissorsandpaper—orevenneedleandthread?Iftheanswerisanemphatic“yes”thenthisisthebookforyou!

WhatIsanArduino?TheArduinoisatoolforbuildingcomputersthatcaninteractwiththephysicalworldaroundyou.Youcanuseittoconnectsensorsthatdetectsound,lightorvibration,thenturnonalight,changeitscolour,moveamotorandmuchmore.TheArduinoisthemagicaldevicethatsitsinthemidstofallofthesethings.Itreadsinfromsensorsmeasuringtherealworld,makesdecisionsbasedonthatdataandthenmakessomethinghappenintherealworld,whetherlight,soundormovement.

TheArduinoisusuallyablueboardaboutthesizeofyourhand.Ithaswhitewritingonitlabellingitsdifferentsectionsandhasallitschipsandcircuitsexposed.TherearedifferenttypesofArduinoboards,andtheyaren’tallblue,butyouwilllearnmoreaboutthatlaterinthe“PartsYouWillNeed”sectionandalsoinAdventures7and8.

TheArduinoisamicrocontroller.Amicrocontrollerisasimplecomputer.Itcan’tdomanythingsatthesametimebutitdoeswhatitistoldtodoreallywell.Youalreadyinteractwithlotsofmicrocontrollerseverydaybecausetheycontrolthingslikemicrowavesandwashingmachines.

Therearealotofdifferenttypesofmicrocontroller,butthespecialthingaboutArduinoisthatitisdesignedforpeoplewhoarejuststartingout.So,ifyouarenewtocodeorelectronics,that’sokaybecausetheArduinoisgreatforbeginners.Butdon’tunderestimateit—itcanstilltakeonbigprojects.

WhatYouWillLearnAftercompletingtheseadventures,youwillhavelearnedhowtosetuptheArduinoprogrammingenvironmentonyourcomputerandhowtowriteanduploadcodetoyourArduinoboard.YouwillfindouthowtoworkwiththreedifferentArduinoboards:theUno,LeonardoandtheLilypadUSB.

YouwilllearnbasicprogrammingconceptsthatyoucanusebeyondworkingwiththeArduino.TheArduinolanguageisbasedontheC/C++language.ThismeansthatasyoulearnhowtocodeArduinos,youarealsolearningabouthowprogrammingworksoncomputerslikealaptoporaRaspberryPi.

Alongsideprogramming,youwillbeintroducedtocircuitsandelectronics.Youwilllearnhowtousesensorstodetectreal-worldsignalslikelightormovement,andyouwilllearnhowtogenerateactionsintherealworld,suchasplayingasoundorturningonalight.

Bytheendofthisbook,youwillhaveabroadunderstandingofwhatyoucandowithanArduinoandbereadytostartdesigningandbuildingprojectideasofyourown!

PartsYouWillNeedIt’sbecomingeasiertobuyArduinoboardsinstores.PopularretailchainslikeMaplinintheUKnowstockArduinos.Bothofthosestoresalsoselltheelectroniccomponentsthatyouneedfortheprojectsinthisbook.Ifit’snotconvenientforyoutogettoastoretherearealsomanyonlineretailerstochoosefrom,andsomeofthesearelistedinAppendixB.

Thissectionexplainsallthepartsyouneedtomakealltheprojectsinthisbook.Manyoftheprojectsusethesamecoreparts.

Ofcourse,themostimportantthingyouneedisanArduinoboard.TherearemanydifferentkindsofArduinoboards,buttheArduinoUnoisthemostcommononeandtheoneyouusethemostinthisbook.YoualsoneedanArduinoLeonardoforAdventure7andaLilypadArduinoUSBforAdventure8.AllthreeboardsareshowninFigureI-1.

FIGUREI-1ArduinoUno(topleft),ArduinoLeonardo(bottomleft)andLilypadArduinoUSB(right)

YouwillneedaUSBcabletoconnectyourArduinoboardtoyourcomputer.FortheArduinoUnoyouneeda“normal”USBcable,butfortheArduinoLeonardoandLilypadArduinoUSByouneedaUSBMicrocable.BotharepicturedinFigureI-2.

FIGUREI-2AUSBandUSBMicrocable

Youusebreadboardstobuildcircuits.Breadboardsletyouconnectcomponentseasilywithouthavingtousesolder.Theycomeindifferentcoloursandsizes.Thelargeronesareusefulformorecomplicatedprojectswithlotsofparts,whereasthesmalleronesaregoodforprojectsthatyouwanttofitinsideasmallspace.TwodifferentsizesofbreadboardsmadefromtwodifferenttypesofplasticareshowninFigureI-3.Adventure3istheonlyprojectthatusesabreadboardinthecompletedproject;theotheradventuresuseabreadboardonlytotestacircuit.Alargerbreadboardwillbeeasiertoworkwith,butifyoucanonlyfindsmallerones,that’sperfectlyokay.

FIGUREI-3Breadboardsindifferentsizesandcolours

Jumperwiresarewiresyouusewhenyoubuildprototypecircuitstotryoutnewconcepts.TheymaybeshortpiecesofstiffwirelikethoseshownontherightinFigureI-4,ortheymaybemoreflexiblewirewithpinsoneitherendliketheonesontheleft.

FIGUREI-4Jumperwires

LEDsareaparticularsortoflight(LEDsstandsforlight-emittingdiodes)thatcomeina

bigselectionofsizesandcolours.FormostoftheprojectsinthisbookyoucanusewhateversizeandcolourofLEDsyoulike.Themostcommonsizeis5mm,butthelarger10mmLEDscanbegreatfuntousetoo.MostLEDsaresingle-colour,butyouuseanLEDinAdventure6thathasfourlegsinsteadofonlytwoandcanchangecolour.InAdventure8youusesomethingcalledaLilypadLED,whichismadeespeciallyforsewingcircuits.AllthedifferenttypesofLEDusedintheprojectsareshowninFigureI-5.

FIGUREI-5DifferenttypesofLED,withacolour-changingLEDontherightandbelowitaLilypadLED

Resistorsareacomponentyoureadmoreaboutintheadventures.Theycomeindifferentvaluesofresistance,whichismeasuredinohms(Ω).Youdon’tneedmanydifferentresistancesfortheprojectsinthebookbutasresistorsaresmallandquitecheapit’sagoodideatobuyextra.Youneedresistorsof68or100Ω,220Ω,10k(10,000)Ω,1M(1,000,000)Ωand10M(10,000,000)Ω.FigureI-6showsthedifferentresistors.

FIGUREI-6Resistorsneededfortheprojectsinthisbook:100Ω(topleft),220Ω(topright),10kΩ(bottomleft),1MΩ(bottommiddle)and10MΩ(bottomright)

Potentiometersaretheelectroniccomponentsbehindvolumeknobsordialsonastereo.Theycomeinmanydifferentsizesandshapes.Somefitintoabreadboardontheirown,liketheblueoneinFigureI-7,whereasothersneedwiressolderedtothemthatcanconnecttoabreadboard,liketheoneinthemiddleinFigureI-7.Largeronesareeasiertomountinaprojectandmaybecalledpanel-mountpotentiometers.

FIGUREI-7Threedifferenttypesofpotentiometer

Aservo,showninFigureI-8,isamotorthatyouuseinAdventure3.

FIGUREI-8Aservomotor

Buttonsareanothercomponentthatcomeinmanyshapesandsizes.Youmighthavenevernoticedthisbefore,buttherearemanydifferentkindsofbutton!Alltheprojectsinthisbookusepush-to-make(theoppositeofpush-to-break)buttonssothosearetheonestobuy;aslongastheyarepush-to-make,youcanuseanykindofbuttonyouwouldlike.Tactilepushbuttonsareverylittlebuttonsthatfitinabreadboard,sotheyaregoodtohavewhenyouaretestingyourcircuit.Foryouractualprojects,panelmountpushbuttonsarebetter.BothareshowninFigureI-9.

FIGUREI-9Atactilepushbutton(left)andthreedifferentpanelmountbuttons(right)

InAdventure4youdiscoverhowtouseshiftregisters,whicharesmallblackchipsyoucanusetocontrolalotofLEDs.Youwantachipthatisa74HC595shiftregister—youfindoutwhatthatmeansintheadventure.Youneedtobuyachipwith16legsonit,asshowninFigureI-10.

FIGUREI-10Ashiftregister

Piezosareusedtodetectvibrationsandcanalsomakesound,likeaspeaker.YouneedonepiezoforAdventure5andsixforAdventure9.Theysometimescomeinsideblackplastichousing,whichisokayfortheoneinAdventure5butyouneedatleastfivewithouthousing(liketheoneinFigureI-11)forAdventure9.

FIGUREI-11Apiezo

Alight-dependentresistorcantellanArduinoboardhowbrightordarkitis.TheselookliketheoneinFigureI-12orcanbealittlebigger.

FIGUREI-12Alight-dependentresistor

HeaderpinsaresmallstripsofmetalthatareseparatedbyplasticsothattheyfitperfectlyintotheholesontheArduinoUno.Theycomeindifferentspacings(calledpitches),soyoushouldmakesureyouget2.54mmmaleheaderpins,liketheonesinFigureI-13.YouneedastripoffiveforAdventure5,butyoucanbuytheminlongerstripsandeasilybreakthemapartintosmallersectionswithpliers.

FIGUREI-13Maleheaderpins

Whenyouthinkaboutcircuitsandelectricity,oneofthefirstthingsyoupictureis

probablywire.Butwireisn’tasingleitem;therearemanydifferentkinds.Wirecanbemadeofasinglepieceofmetal(calledsolidcore)oralotofsmallerpiecesofmetaltwistedtogether(calledstranded).FigureI-14showssolidcoreandstrandedwire.Solidcorecanbeusefulforbreadboardsbutit’sverystiff.Strandediseasiertobend,butyouneedtosoldertheendofitinordertogetittofitinabreadboard.Youcandecideforeachprojectwhichsortyouwanttoworkwith—thereisn’tarightorwrongtypetouse.

FIGUREI-14Solidcorewire(left)andstrandedwire(right)

Wireusuallycomeswithsomekindofcoatingthatdoesn’tconductelectricity.ItmaybecolouredplasticlikethewireontherightinFigureI-15,oritmaybeenamelledlikethewireontheleft.Youcandecidewhichwireworksbestinyourprojects.TheenamelledwireworkswellintheaugmentedwindchimeinAdventure5becauseit’sverythinandletsthechimesswingeasily.However,youcouldbuildthewindchimeusingadifferentthinwire.

FIGUREI-15Enamelled(left)andplasticcoated(right)wire

Solderislikeaconductiveglueforelectronics.ItsometimescomesonspoolsindifferentthicknesseslikeinFigureI-16.Theprojectsinthisbookdon’trequireverysophisticatedsoldering,soyoudon’thavetoworryaboutwhichthicknesstobuy.Justaboutanythicknesswillworkokay.Theonlyimportantthingtowatchoutforistomakesureyoubuysolderforelectronics—don’tbuysolderthat’susedforplumbing!

FIGUREI-16Solderonspools

Afteryoubuildyourprojects,youmightwanttorunthemwithouthavingtoconnectthemtoyourcomputerforpower.Ifso,youcaneitherpoweryourprojectfromapowersupplyorfromabattery.Ifyouuseapowersupply,it’seasiesttobuyaUSBwalladapter—apowersupplythatletsyouconnectaUSBcabletoawallsocket,withtheotherendoftheUSBcablepluggedintoyourArduinoboard.Ifyou’dliketouseabattery,thebestoptionistogeta9VbatteryconnectorwithaDCbarrelontheend.ThereisablackplugsocketonyourArduinoboardwhereyoucanplugintheconnector.BothoptionsareshowninFigureI-17.FortheLilypadArduinoUSB,youcanuseaLiPobattery,butyoureadmoreaboutthatinAdventure8.

FIGUREI-17A9Vbattery-to-DC-barrelconnector(left)andaUKplugforaUSBcable(right)

WhenyouworkwithsoftcircuitsinAdventure8,youneedalligatorclipsliketheonesinFigureI-18,whichyouuseinsteadofjumperwires.

FIGUREI-18Alligatorclips

InAdventure8,youalsouseconductivethread,whichisthreadspunwithconductivefibres.Therearedifferentkindsavailablefromdifferentmanufacturers,butalltheoptionsareasilvercolourasshowninFigureI-19.

FIGUREI-19Conductivethread

ToolsYouWillNeedJustasyouneedhammersandsawstobuildsomethingwithwood,youneedspecialtoolstoworkwithelectronics.

Whenyoutestyourcircuitsyouuseabreadboard,butyoueventuallyneedtogobeyondthebreadboard.Forexample,youmightneedtoaddlongerwirestoacomponentsoitfitsinsideyourhousing,oryoumightwanttoconnectcomponentstogetherinamorepermanentwaythatwon’tfallapart.

Thefirstthingyouneedisasolderingiron.Solderislikeglueforelectronics,butitonlyworksathightemperatures(thinkofitasahotglueforelectronics).Asolderingironisatoolthatgetsveryhot(muchhotterthananoven)sothatitcanmeltsolder.Onlyuseasolderingironwhenanadultisnearbytohelpyou.

Asolderingironmaybeasinglehand-heldtoolthatplugsintothewall,liketheoneinFigureI-20.Oritmayplugintoaboxwithatemperaturedialthatplugsintothewall.Eitherkindisokay.Theimportantthingistobuyonethatismeantforsmallelectronicsandnotplumbingoranyotheractivity.

FIGUREI-20Asolderingiron

Wireoftencomeswithaplasticcoatingthatisaninsulatorthatdoesn’tconductelectricity.Yousometimesneedtoremovethisplasticcoatingfromtheendsofthewiresoyoucanfititintoabreadboardorsolderacomponenttoit.Youcouldalwayscarefullyuseaknifeorcutterstotryandremovetheplastic,butthatcanbeaveryfrustratingmethod.Itiswellworthbuyingtherighttoolforthejob.Enterthewirestripper!

Wirestripperscomeinlotsofshapesandsizes,asyoucanseeinFigureI-21.Choosewhicheveroneyoulikebest.

FIGUREI-21Differentkindsofwirestripper

Wirecuttersdowhatyouexpect—theycutwires.Besuretogetsmalleronesthateasilyfitinyourhandasyouwillbeworkingwithsmallcomponentsandthinwires.FigureI-22showsthekindofwirecuttersyoucouldget.

FIGUREI-22Wirecutters

Pliershelpyoushapeandbendwires.Theycomeindifferentsizesandshapes,butasmallergeneralpurposepairofpliersisallyouneedfortheprojectsinthisbook.EitherofthepairsinFigureI-23wouldworkwell.

FIGUREI-23Pairsofpliers

Thenexttoolmayseemabitdaunting,butitcanbeyourbestfriendwhenworkingwithelectronics.It’sthemultimeter!Itmeasuresmultiplethings(that’showitgotitsname),withresistanceandvoltagebeingthemostusefultothebeginner.Theyrangefromverycheaptoextremelyexpensive.Whenyouarechoosingoneforyourself,youdon’tneedtospendalotofmoney,especiallyifitisyourfirstmultimeter.Youprobablywantonethatauto-ranges,thoughthat’snotessential,butyoudefinitelyneedonewithacontinuitytest.(Whenyoulookatmultimetersinastore,auto-rangingandcontinuitytestingwillbelistedintheirfeatures.)Auto-rangingmeansthatyoudon’tneedtoknowtheapproximatevalueofwhateveryouaretestingbeforeyoutestit.Acontinuitytestiswhenthemultimeterbeepswhenanelectricalconnectionismadebetweentheprobes.FigureI-24showsalessexpensivemultimeter,whichisn’tauto-rangingbutdoeshaveacontinuitytest.

FIGUREI-24Amultimeter

Thefinaltoolsarenotspecificallyusedwithelectronicsbutarebeessentialforconstructingthehousingforyourprojects:scissorsandautilityknife(FigureI-25).Alwaystakecarewhenusingeither!

FIGUREI-25Apairofscissorsandautilityknife

SoftwareYouWillNeedWhenwetalkaboutArduino,itiseasytothinkabouttheboardandnothingelse.Afterall,that’sthepartyouphysicallyplaceintoyourproject.However,theArduinoneedscodeinordertodoanything.YouwritethatcodeonanothercomputerfirstandthenuploadthecodetotheArduinoboard.

ThecompanythatmakestheArduinoboardalsomakesthesoftwarethathelpsyouwriteanduploadthecode.It’sfreetodownloadfromhttp://arduino.cc/en/Main/Software.

Adventure1takesyouthroughthestepstosettingupthesoftwareonyourcomputer.

ThecircuitschematicsanddiagramsofcircuitsonbreadboardsinthisbookaremadewithaprogramcalledFritzing,whichisalsofreeonlineathttp://fritzing.org/download.YoucanevenuseFritzingtostartdesigningyourownprojects!

OtherUsefulMaterialsWritingcodeandbuildingacircuitisonlyonehalfofcompletingaproject.Yourprojectdoesn’tcomealiveuntilitissurroundedbysomekindofhousing.Whetherit’sagameoraninteractivelight,whenitisjustacircuitonabreadboardithasn’tyetreacheditsfullpotential.

So,tomaketheprojectsinthisbook,youusemanylow-techtechniquesalongsideyournewlyacquiredhigh-techskills.Scissors,paperandglueformthebasisofmanyofyourprojects.It’sgoodtohavethefollowingitemstohand,butit’sneverabaddecisiontoadddecorativeitemslikeglitterthatallowyoutoletyourimaginationrunriot!Inparticular,youneedthefollowingthings:

SmallcardboardboxesorshoeboxesCard,cardboardandpaperPaintfordecoratingStringoryarnWhitecraftglue,glue-stickorahotgluegunPaintbrushAballoon(forAdventure6)Amarble(forAdventure9)

WhatIAssumeYouAlreadyKnowBecauseyou’vestartedreadingthisbook,I’mgoingtoassumeyou’realreadyinterestedintechnology!Youdon’tneedtohavedoneanycomputerprogrammingpreviouslyorbuiltanycircuits(that’swhatthisbookisexplaining!),butIdoassumethatyouhaveusedacomputerbefore.

YouneedacomputertoworkwiththeArduinobutitdoesn’treallymatterwhatoperatingsystemyourcomputeruses—MacOSX,WindowsormanydifferentLinuxdistributions(seehttp://playground.arduino.cc/Learning/LinuxforguidanceonwhichLinuxdistributionsyoucanuse).Iassumethatyouarecomfortablegoingonlineanddownloadingfilesandthatyouknowhowtofindandopenapplicationsonyourcomputer.

Youmayneedanadministratorpasswordtoinstallsomeofthesoftware,soifyoudon’tknowthepasswordforyourcomputeritwillhelpifsomeonewhodoesknowthepasswordisnearbywhenyouinstallit.

HowThisBookIsOrganisedThisbookguidesyouthroughprogrammingyourArduinoboardandconstructingcircuitsinnineadventures.Eachadventurestartsbyintroducingthenewskillyouneedinordertocompletethestandaloneprojectattheendoftheadventure.Thenewskillmightbelearninghowtouseanewcomponentsuchasamotor,forexample,orhowtodosomethingcleverincode.

ThemostimportantadventureforyoutostartwithisAdventure1.IthelpsyouinstallthesoftwareneededtouploadyourcodeontoyourArduinoboard.Afterall,ifyoudon’tdothat,therestoftheadventureswon’tbemuchfun!

Adventures2to9buildonpreviousadventures,soIrecommendthatyoufollowtheadventuresinorder.Ofcourse,ifyoupreferyoucanthrowcautiontothewindanddotheminanyorderyouwant.Youcanalwayslookupmoreguidanceonaparticulartopicfromanearlieradventureifyoucomeacrosssomethingyoudon’tknow.

AswellashelpingyousetupyourcomputersoyoucanprogramyourArduinoboard,Adventure1alsoguidesyouthroughyourfirstArduinoprogram,calledasketch.YouevenbuildyourfirstcircuitonabreadboardandcontrolanLED.

InAdventure2youlearnhowtocontrolmorethanoneLED,howtoprintmessagesfromyourArduinoboardtoyourcomputerandhowtouseyourfirstsensor—apotentiometer.Yougettoputyournewskillsintopracticebybuildingastatusmessagesignthatlightsuptoshowthatyoudon’twanttobedisturbed.

InAdventure3youareintroducedtoyoursecondsensor:apushbutton.Youcombineitwithpotentiometerstocontrolamotor.Youalsolearnhowtouseforloopsincomputercodetorepeatthesamethingoverandoveragain.Puttingitalltogether,youbuildacombinationsafethatopensonlywhenthecorrectcombinationisdialed.The“safe”isonlyacardboardbox,soit’sprobablynotfitforstoringthefamilyjewels,butit’sgoodenoughtoprotectyourfavouritesweets.

Adventure4showsyouhowtobreakupyourcodeintobite-sizedpiecesusingfunctions.YouthenusefunctionstocontrolmultipleLEDsusingspecialchipscalledshiftregisters.Inthefinalprojectoftheadventure,youmakeletterswithembeddedLEDsinthestyleofoldcarnivalsigns.

Adventure5addssoundtothegrowinglistofactionsyoucancontrolwithyourArduino.Youfindouthowtomakelistsincodetoplayshorttunesoveranewcomponent—apiezo.Youthenmakeanaugmentedwindchimethatputsanelectronictwistonatraditionalinstrument.

Adventure6introducesmoresubtlecontrolsbyshowinghowyoucanfadeanLEDandnotjustturnitonandoff.YoualsoexpandtheabilitiesofyourArduinobyinstallingnewlibrariesthatdon’tcomewiththeArduinosoftware.Youthencombineyournewskillswithathree-colourLEDtocreateacrystalballthatmagicallychangescolour!

InAdventure7youareintroducedtoanewArduinoboard,theArduinoLeonardo.You

masteroneoftheexcitingfeaturesoftheLeonardo:makingacomputerthinktheArduinoisakeyboard.Youaddanewsensorthatdetectslightandmakeacomputergamecontrollerthatletsyouplayagamewithawaveofyourhand.

InAdventure8yougettoworkwithanotherArduinoboardandbuildcircuitsusinganeedleandthreadinsteadofwireandasolderingiron.Thisadventurehelpsyoubecomeamasterofarraysandcreateahoodiethatdisplaysasecretmessage.

Andfinally,Adventure9isthebigadventure!Youhavetochancetoputtogetheralltheskillsyou’vegainedovertheearlieradventurestocreateamarblemazegamethatautomaticallykeepstrackofyourscore,countsdowntheremainingtimeandplayssoundeffects.Youuseafamiliarcomponentinanewway,usingapiezotodetectvibrationsaswellasplaysoundeffects.

AppendicesAandBprepareyouforfurtheradventuresbeyondthisbook.AppendixApointsyoutowardotherArduinoresourcesinprintandonline,andAppendixBshowsyouwheretobuytoolsandcomponentsforyourprojects.

ConventionsThroughoutthisbookthereareboxestohelpyouout:

Theseboxesexplainconceptsortermsyoumightnotbefamiliarwith.

Theseboxesgiveyouhintstomakeyourcodingandbuildingeasier.

Theseboxescontainimportantwarningstokeepyouandyourcomputersafewhencompletingasteporproject.

Theseboxesfeaturequickquizzesforyoutotestyourunderstandingormakeyouthinkmoreaboutatopic.

IntheseboxesIexplainthingsorgiveyouextrainformationIthinkyou’llfinduseful.

Theseboxespointyoutovideosonthecompanionwebsitethattakeyouthroughthesteps.

Youwillalsofindtwotypesofsidebarinthebook.TheChallengesidebarsaskyouhowmightexpandonthenewskillsyouarelearningoraddnewfeaturestoyourprojects.TheDiggingintotheCodesidebarsgodeeperintotheprogrammingconceptsusedinArduinoprogramming.

Whenyouarefollowingtheinstructionsinthebook,youshouldtypeinthecodeexactlyasyouseeit—every;isveryimportant!However,thespacesbetweenwordsdon’tmatter.Spacesareusedtomakethecodeeasiertoread,butitdoesn’tmattertotheArduino.

Forexample,bothofthefollowinglinesmeanthesamething:

if(i<4)

if(i<4)

YoursketchcouldbewrittenasasingleverylonglineoftextanditwouldstillrunontheArduino!Butitwouldbeverydifficultforanotherprogrammertounderstandwhatis

happening.Addingspacesandnotestoexplainwhatishappeninginthecodeisthebestwaytoprogram.

Sometimesalineofcodeistoolongtofitononelineofthisbook.Ifyouseethesymbolattheendofalineofcode,thatmeansthatlineandthenextlineshouldbetypedasa

singlelineofcodeinyourArduinosoftware.

Forexample,thefollowinglineshouldbetypedononeline,nottwo:

Serial.println("Hello,fromthesetup()functionin

yourArduinoUno!");

Tohelpyoukeeptrackofthenewcodingconceptsyoulearn,thereisaQuickReferenceTableattheendofeachadventure,whichlistsanynewfunctions,datatypesorotherprogrammingcommandsthathavebeenintroducedinthatadventure.

Whenyoucompleteanadventure,youunlockanachievementandcollectanewbadge.YoucancollectbadgestorepresenttheseachievementsfromtheAdventuresinArduinowebsite(www.wiley.com/go/adventuresinarduino).

TheCompanionWebsiteThroughoutthebook,you’llfindreferencestotheAdventuresinArduinocompanionwebsite,www.wiley.com/go/adventuresinarduino.Here,you’llfindtutorialvideostohelpyouthroughthephysicalmakingofyourprojectsalongwiththecodeused.Itcanbeveryfrustratingtotrackdownamistakeafteryou’vetypedincodefromabookbyhand.Theimportantthingisunderstandingwhatthecodeisdoingandnotjusthowtotypeitalloutyourself(oratleastnotwhenyouarefirststartingout)!

ReachingOutYou’llfindalotoftipsinAppendixAaboutwheretogoforhelpbutthefirstplaceyoushouldalwayslookistheArduinowebsite(www.arduino.cc).IthaslotsofusefulinformationintheLearningsection,andyoucanalwaysaskquestionsintheForum.

Youcanalsocontactmebysendingmeamessagethroughthewebsitewww.adventuresinarduinobook.com.

Timetostartyouradventures!

YOUWILLSOONbecreatingexcitingprojectsthatbridgethephysicalanddigitalworlds!You’lllearnhowtowritecodethattriggerssound,controlsmotorsandflasheslights.TheArduinoistheperfecttoolforcombiningcircuitsandcode!

YouwillusethesamethreestepsforeachprojectyoubuildwithyourArduino:

1. WritethecodethattellstheArduinoUnowhattodoonyourcomputerusingtheArduinosoftware.

2. ConnectyourArduinoUnotoyourcomputer,anduploadyourcodeontotheboard.3. BuildandconnectyourcircuittoyourArduinoUno.

Butfirstthingsfirst.Beforeyoucandoanythingelse,youneedtodownloadandinstalltheArduinosoftwareandsetupyourcomputertoprogramyourArduinoUno.That’swhatyouwillbedoinginyourfirstadventure.Then,whenyou’vegoteverythingworkingasitshould,you’regoingtostartyourfirstArduinoproject—controllingwhenalightturnsonandoff.

WhatYouNeedTogetstarted,youneedthefollowingthings.Figure1-1showstheelectroniccomponentsyouwillneed.

AcomputerAnArduinoUnoAUSBcableAnInternetconnectionsoyoucandownloadtheArduinosoftware

FIGURE1-1AnArduinoUnoandUSBcable

DownloadingandInstallingtheArduinoSoftwareonYourComputerInordertorunArduinoprograms,inadditiontoanArduinoUnoyouneedacomputerandsomespecialsoftwaretomaketheArduinowork.YouwillbewritingthecodethatrunsontheArduinoUnoonanothercomputerfirst,andwillthenuploadittotheboard.Soundscomplicated,doesn’tit?Don’tworry;you’llbeguidedthroughtheprocessstepbystep.Andit’snotasdifficultasitsounds.

You’regoingtouseapieceofsoftwaretowritethecodeandthenuploadit.ThispieceofsoftwareiscalledtheArduinoenvironment,orintegrateddevelopmentenvironment(IDE).ItisavailableforfreefromtheArduinowebsiteathttp://arduino.cc/en/Main/Software(seeFigure1-2).

FIGURE1-2YoucandownloadtheArduinoIDEforyourcomputerfromtheArduinowebsite.

Anintegrateddevelopmentenvironment(IDE)isasoftwareapplicationthatisusedtowritecomputercodeinaparticularlanguage;it’salsoreferredtoasaprogrammingenvironment.Theapplicationcancreateandeditcode,aswellasrun(orexecute)thecode.ManyIDEsalsoprovidefeaturestohelpprogrammersdebugtheirprograms—inotherwords,checktheirprogramsforerrors.

YouarenowgoingtodownloadandinstallthelatestversionoftheArduinosoftwaredesignedforyourparticularcomputer’soperatingsystem,usingthestepsoutlinedhere.Whenthisbookwaswritten,1.0.6wasthecurrentversionofthesoftware.Youcanseewhatthecurrentversionisbyvisitinghttp://arduino.cc/en/Main/Software.Youcan

findthecurrentversiontowardsthetopofthepage.Afteryouhaveinstalledthesoftware,youcanseewhatversionyouareusingbyreadingthetitlebarofthewindowthatappearswhenyoulaunchtheArduinoIDE.

ThesoftwarecanrunonWindows,MacorLinuxcomputers,butdependingonyourcomputer’soperatingsystem(OS),youmayneedtoinstallboththeIDEandanotherpieceofsoftware,calledadriver.Thisadventuredescribeswhatyouneedtodo,butyoucanalsovisithttp://arduino.cc/en/Guide/HomePage,whichhaslotsofguidanceonhowtogetthesoftwareinstalled.

HaveyourArduinoUnoandUSBcabletohandasyouinstallthesoftware,becauseyoumightneedthemforsomeoftheinstallationsteps,dependingonyourcomputer’soperatingsystem.

Adriverisapieceofsoftwarethatletsyourcomputercommunicatewithanexternaldevice,suchasaprinterorakeyboard.

InstallingArduinoSoftwareonaMacItisquitesimpletoinstallthesoftwareonaMac.Youdon’tneedtoinstalladriver,onlytheArduinoIDE.Justfollowthesesteps:

1. InyourInternetbrowser,opentheArduinodownloadpageathttp://arduino.cc/en/Main/Software.

2. SelecttheMacOSXzipfilefromthelistofcurrentArduinodownloads.3. Findthefilecalledarduino-1.0.6-macosx.zipandunzipitbydouble-clickingit.

NowmovetheArduino.appfileintoyourApplicationsfolder.4. Afteryou’veinstalledthesoftware,plugoneendofyourUSBcableintoyour

Arduinoboard(showninFigure1-3)andtheotherendintoyourcomputer.Amessageaboutanewnetworkdevicemayappearonscreen.Ifthathappens,youcanjustcancelorclosethemessagewindow.

FIGURE1-3PlugtheUSBcableintotheArduinoUnoandthenconnectittoyourcomputer.

Ifyouhaveanyproblems,visithttp://arduino.cc/en/Guide/MacOSXformorehelp.

ToseeavideoofhowtoinstalltheArduinoIDEonacomputerrunningMacOSX,visitthecompanion

siteatwww.wiley.com/go/adventuresinarduino.

InstallingArduinoSoftwareonaWindowsPCYouneedtofollowanumberofstepstoinstalltheArduinosoftwareonWindows7,VistaandXP(seetheTipsandTricksboxforWindows8).Youwillbeinstallingtwothings:thesoftwareandthedriver.

1. InyourInternetbrowser,opentheArduinodownloadpageathttp://arduino.cc/en/Main/Software.

2. StartbydownloadingthefilecalledWindowsZIPfile.3. FindthedownloadedzipfileandunzipittotheProgramFilesfolder.Itshould

containmultiplefoldersandfiles,includingafoldercalleddriversandafilecalledarduino.exe.Ifyouwouldlike,youcanright-clickarduino.exeandcreateashortcuttoplaceonyourDesktop.

4. PlugoneendoftheUSBcableintoyourArduinoboardandtheotherendintoyourcomputerasshowninFigure1-3.YoushouldseelightsilluminateonyourArduinoUno.Thisjustmeansithaspower.

5. YourcomputerwillnowstarttolookforadrivertousewiththeArduinoboard.Yourcomputermayfindthedriveronitsown,but,dependingontheversionofWindowsyourcomputerisrunning,youmayneedtofollowdifferentstepstofinishinstallingthedriver.Youmayneedtoknowanadministratorpasswordforthecomputerandmightneedsomehelpwithsomeonewithmorecomputerexperience.Youcanalwaysvisithttp://arduino.cc/en/Guide/Windowsformoredetailedinstructions.

6. ClicktheStartmenuandopentheControlPanel.7. WhileintheControlPanel,navigatetoSystemandSecurity.ClickSystem,andwhen

theSystemwindowappears,opentheDeviceManager.8. InsidetheDeviceManagerlookunderPorts(COM&LPT).Youshouldseeaport

namedArduinoUNO(COMxx).Ifyoudon’tseeaCOM&LPTsection,lookunderOtherDevicesforUnknownDevice.

9. Right-clickArduinoUNO(COMxx)portandchoosetheUpdateDriverSoftwareoption.

10. IfyouarerunningWindowsXPortheHardwareUpdateWizardappears,gotohttp://arduino.cc/en/Guide/UnoDriversWindowsXPandfollowthescreenshotstoinstallthedriverslocatedinthefolderyoudownloadedandunzipped.

11. IftheHardwareUpdateWizarddoesn’tappearandinsteadyouseeawindowwiththeoptionsSearchAutomaticallyforUpdatedDriverSoftwareandBrowseMyComputerforDriverSoftwareappears,clickBrowseMyComputerforDriverSoftware.

12. Navigatetothefolderyoudownloadedandunzipped.Gotothefolderinsideitcalleddriversandselectarduino.inf.

Wow,thatwascomplicated.Luckily,youdon’thavetodothatagain.Youonlyneedtodoitonce.ThestepsmightchangewhennewversionsoftheArduinoIDEarereleasedorif

thereareupdatestoyouroperatingsystem.YoucanalwaysgototheArduinoforumboardforinstallationproblemsathttp://forum.arduino.cc/index.php?board=2.0.Youcanlookoverthequestionsaskedbyothersandevenaskyourownifyoucan’tfindaquestionsimilartotheproblemsyouarehaving.

Ifyourunintoanyproblems,firstvisithttp://arduino.cc/en/Guide/Windowsformorehelp.

Youcanalsovisithttps://learn.adafruit.com/lesson-0-getting-started/installing-arduino-windows,www.dummies.com/how-to/content/how-to-install-arduino-for-windows.html,orhttps://learn.sparkfun.com/tutorials/installing-arduino-ide/windowsforevenmoretipsincludingextraguidanceforinstallingonWindows8.

IfyourcomputerrunsWindowsXP,youcanfollowalongwiththescreenshotsathttp://arduino.cc/en/Guide/UnoDriversWindowsXPtoinstallthedrivers.

InstallingArduinoSoftwareonaLinuxMachineIfyourcomputerrunsLinux(ifyouareusingaRaspberryPi,forexample),youshouldfirstvisittheonlinedocumentationforLinuxandArduinoathttp://playground.arduino.cc/Learning/Linux.TherearemanydifferenttypesofLinux,soIhaven’tlistedthemallhere,andifyourcomputerrunsaLinuxdistribution,youlikelyalreadyknowhowtoinstallnewsoftware.ItisprobablyeasiesttoinstalltheArduinoenvironmentbyusingapackagemanager.Here’showtodotheinstallationonaDebianvariantofLinux,suchasRaspbianonRaspberryPi.Onacommandline,enterthefollowingcommand:sudoapt-getinstallarduino

Thiscommanddownloadsandinstallsthesoftware.Alternatively,youcandownloadthe32-and64-bitapplicationsdirectlyfromtheArduinodownloadpageathttp://arduino.cc/en/Main/Software.Youdon’tevenneedtoworryaboutcompilingsourcecode,butdon’tforgettoreadtheguidelinesforyourdistributionathttp://playground.arduino.cc/Learning/Linux.

IfyouareusingaRaspberryPiorotherLinux-basedsystem,Iamassumingthatyouknowhowtousethecommand-lineinterfacetoinstallsoftwareforwhateverversionofLinuxyouarerunning.IfyouneedmoreinformationorarefresheronusingtheRaspberryPi,checkoutAdventuresinRaspberryPibyCarrieAnnePhilbin(JohnWiley&Sons,Inc.,2014).

ExploringtheArduinoIDEWelldone!Nowthatyouhavethesoftwareinstalled,you’rereadytostartusingtheArduinoIDE!It’stimetolaunchthesoftware.IfyourcomputerisaMac,gotoApplicationsanddouble-clickArduino.IfyourcomputerisrunningWindows,eitherdouble-clicktheshortcutontheDesktop(ifyoumadeoneasdescribedearlierintheadventure),orgotothefolderyoudownloadedearlieranddouble-clicktheArduinoapplication.IfyourcomputerisrunningLinux,starttheArduinoIDEeitherfromthecommandlineorbydouble-clickingtheprogramicon.TheArduinoprogramicon(seeFigure1-4)looksthesameonMac,WindowsandLinux.

FIGURE1-4TheArduinoprogramicon

WhentheArduinoIDEhasfinishedstarting,awindowsimilartotheoneshowninFigure1-5willappear.

FIGURE1-5TheimportantpartsoftheArduinoIDE

First,you’regoingtofindoutaboutsomeofthebasicfunctionsoftheArduinoIDE.TherearesixbuttonsatthetopoftheArduinowindow(seeFigure1-5),andmostofthemareeasytofigureout.ThemiddlethreebuttonsareNew,OpenandSave.ClickingtheNewbutton(surprise!)startsanewArduinofile,theOpenbuttonopensanexistingArduinofile,andtheSavebuttonsavesthecurrentthefile.You’llnoticethere’sabuttononitsownonthefarright—youwillbefindingoutaboutthisinAdventure2.Thatjustleavesthetwobuttonsontheleft.

ThebuttonthatlookslikeatickistheVerifybutton.Whenyouclickthisbutton,theArduinocompilesthecode;inotherwords,ittakesthecodeyouhavegivenitandtranslatesitintosomethingtheArduinoboardcanunderstand.Thereisasecondthingthisbuttondoes.IftherearepartsofthecodethatArduino’scompilerdoesn’tunderstand—perhapsasemicolonwasmissedoutoratypowasmadewhenthecodewastyped—itprintsouttheerroratthebottomoftheArduinoIDEwindow.Ittriestobehelpfulwithwhatitprints,butsometimesitdoesn’tmakesense!Laterthisadventuregoesoversomeofthecommonerrormessagesandwhattheymightmean.

Compilingcodeistheprocessoftakingcodewrittenbyahumanandturningitintoinstructionsthatcanbeunderstoodbyamachine.

Don’tworrytoomuchabouthowthishappensyet.AllyouneedtoknowfornowisthattheVerifybuttonisusedtoturnyourcodeintosomethingtheArduinocanunderstand,anddeterminethatthecodeisfreefromsimpleerrors.Afteryouhavedonethat,youclickthefinalbutton,whichistheUploadbutton.ThiscompilesanduploadsthecodetotheArduinoUno.Thisisthebuttonyouwillprobablyusemost,asitputsyourcodeontotheArduinoUno.TheVerifybuttoncanbeusefulifyouarewritingcodeanddon’thaveyourArduinoUnonearbybecauseitmeansyoucanatleastcheckifyouhaveanysimpleerrorsinyourcode,althoughyouwon’tknowifyourcodecompletelyworksuntilyoucanuploaditontoaboard.

UsingBlinktoTestThatEverythingIsSetUpCorrectlyYoucanwritecomputercodeforadevicelikealaptoporRaspberryPiandthenrunitonthesamecomputeryou’vewritteniton.WithArduino,it’sabitdifferentbecauseanArduinoboardcan’tprogramitself,soyouhavetowritetheArduinocodeonacomputerthatcanruntheArduinoIDE.TheIDEthentakesthecodethathumanscanwriteandreadandtranslates(orcompiles)it,turningitintocodethattheArduinoboardunderstands.TheIDEthencopiesanduploadsthecompiledcodeontotheArduinoboard.

Softwaredevelopersusebasicprogramstotestthattheircomputerisworkingastheywouldexpect.ThesearecalledHelloWorldprograms.

AHelloWorldprogramisverysimple.Ifyouwerelearninganewprogramminglanguage,youwouldwriteaprogramthatwouldjustprintthephrase“Helloworld”tothescreen,whichwouldshowyouthateverythingwassetupproperly.Butwait—theArduinodoesn’thaveascreen!AfteryouloadthecodeontheArduinofromyourcomputer,itdoesn’ttalktothecomputeranymore;alltheUSBcabledoesisprovidetheArduinowithpower(thoughyoufindoutinthenextadventurehowtosendmessagestothecomputerthroughtheUSBcable).

WhattheArduinoboardcandoisblinkalight.Itevenhasonebuiltintotheboardforexactlythispurpose.There’satinyyellowororangelight-emittingdiode(LED)nearthenumber13ontheboard(seeFigure1-6).ThisLEDisusefulbecauseyoucanprogramittoturnonandoffinordertoquicklycheckthattheArduinoboardisworking.Youdon’tneedanythingbesidesyourcomputer,aUSBcableandyourArduinoboard.

FIGURE1-6Thebuilt-inLEDontheArduinoboardisnearthenumber13.

TheArduinoIDEcomeswithsomeexamplecodetohelpgetyoustarted.OneoftheseexamplesistheBlinkprogram,orsketch,whichisusedastheHelloWorldprogramforArduino.You’renowgoingtousethattocheckeverythingisworkingasitshould.

AnLED,orlight-emittingdiode,isanelectricalcomponentthatlightsupwhenelectricalcurrentflowsthroughit.Adiodeonlyletselectricityflowinonedirection,soanLEDlightsuponlywhenthelonglegisconnectedtothepositivesideofapowersourceandtheshortlegisconnectedtothenegativeside.Iftheyareswitched,theLEDwon’tlightup.

Arduinoprogramsareoftenreferredtoassketches,likequickdrawingsartistsmake.

UploadingBlinkTotestthatyourArduinoUnocanreceivemessagesandnewprogramsfromthecomputerwithoutanyproblems,youneedtocompileanduploadtheBlinksketch.SelectFile ⇒ Examples ⇒ 01.Basics ⇒ Blink(seeFigure1-7)toopenanewwindowwiththeBlinksketch.

FIGURE1-7OpeningtheBlinksketch,whichislocatedintheexamplesthatareincludedwiththeArduinoIDE

Beforeyouuploadyourcode,youfirstneedtochecktwosettings:theboardandtheport.YouneedtomakesurethesesettingsarecorrecteachtimeyoulaunchtheIDE.Afteryouhavesetthem,youdon’tneedtochangethemagainuntilyouquitandstarttheIDEagainatalatertime.Tofindtheboard,selectTools ⇒ Boards(seeFigure1-8).YoushouldseealistofallthedifferentArduinoboards.Makesureyouselecttheboardyouareusing.(ThiswillbeanUno,butifyou’renotsure,itiswrittenontheboarditself.)

FIGURE1-8Selectingtheboardyouareusing

You’llfindtheportunderTools ⇒ SerialPort(seeFigure1-9).Selecttheportyouareusing,thesamewayyoufoundtheboard.MakesureyouhavepluggedyourboardintoyourcomputerwiththeUSBcable,ortheportwon’tappearonthelist.

FIGURE1-9SelectingtheportyourArduinoboardispluggedinto

Itmaynotbeobviouswhichportyoushouldselectifthereismorethanonelisted.YoucantrylookingatthelistwhentheArduinoboardisnotpluggedin,thenpluggingintheboardandlookingagain.Ifoneappearedthatwasn’ttherebefore,thatisprobablywhatyoushouldselect.

IfyouareusingaMac,lookfortheportthatstartswith/dev/tty.usbmodem.OnaWindowscomputer,theportisjustlistedasaCOMport.InLinux,theportstartswith/dev/ttyACM.Itwon’thurtanythingifyoudon’tselecttherightport,soifyou’renotsure,justselectaportandclicktheUploadbutton.Ifyougetanerrormessage,tryselectingthenextportinthelist,andcontinuedownthelistuntilyoufindtheportthatyourArduinoboardison.

RememberthatyouneedtoplugyourUSBcableconnectedtoyourArduinoboardintoyourcomputer.Yourportwon’tshowupinyourlistofportoptionsiftheboardisn’tconnectedtothecomputer!

Afteryouhaveselectedyourboardandport,youarereadytouploadyourcode—thisistheBlinksketchyouhavealreadyopened.Todothis,simplyclicktheUploadbutton.Ifyouhaveforgottentoselecttheport,amessagemaypopupaskingyoutoselectone.

Ifyouhaveeverythingsetupcorrectly,youwillseeamessagetowardsthebottomoftheArduinoIDEwindowthatsaysCompilingSketchandthenUploading.Ifthesketchhasbeenuploadedwithoutanyproblems,youwillseeaDoneUploadingmessageasshowninFigure1-10.

FIGURE1-10MessageintheArduinoIDEaftersuccessfullyuploadingyourcode

LookattheLEDnexttothenumber13onyourboard.Isitflashingonforonesecondthenturningoffforonesecond?Ifso,success!Welldone.Ifnot,orifanyorangetexthasappearedatthebottomofyourArduinoIDE,thenextsectionwillhelpyoutroubleshootwhatmightbegoingwrong.

YouwillbesoonmakingchangestoyourBlinksketchandevenwritingnewsketchesofyourown.It’simportanttorememberthatthecodeyouwriteintheIDEhastobeuploadedtotheArduinoUno.Everytimeyoumakeachangetothecode,uploaditagaintoyourboard!

TroubleshootingCommonProblemsWhensomethinggoeswrongwhenyou’retryingtouploadcodetoanArduinoboard,amessagefromsomethingcalledavrdudemightbeprintedatthebottomoftheArduinoIDE(suchastheoneshowninFigure1-11).

FIGURE1-11Acommonerrorwhenthecomputercan’ttalkwiththeArduino

TheArduinoboardisbuiltaroundamicrocontroller(computer)chipmadebyacompanycalledAtmel.ThischipisatypeofmicrocontrollercalledanAVRandtheprogramthattheArduinoIDEusestotalktotheArduinoboardiscalledavrdude.Sowhenyougetmessagesfromavrdude,itmeanssomethinghasgonewrongwiththecommunicationbetweentheboardandthecomputer.Usuallyit’sthatthecomputeristryingtouseavrdudetosendanewsketchtotheArduinoUno,butthecomputercan’tfindit.Problemscouldbecausedbyselectingthewrongport,butifyouhavetriedalltheportstheremaybesomethingelsegoingwrong.

TheeasiestthingtotrywhenyougetanerrorfromavrdudeistounplugtheArduinoboardfromtheUSBcable(thisremovesthepowerandturnsitoff).Thenplugitbackinagain.Ifyoustillhaveproblems,tryunpluggingtheArduinoboardandthenquittingtheArduinoIDElikeyouwouldanyotherapplication.LaunchtheIDEagainandconnecttheArduinoUnooncemoretoseeifyoucanuploadanewsketch.

Ifyou’vedoneallthatandyoustillcan’tuploadsketchestotheArduinoboard,trygoingthroughtheinstallationprocessfortheIDEanddriversagain.

TheArduinowebsite(http://arduino.cc)isagreatresourcewithlotsoftutorials.Italsohostsaforumwhereyoucanpostquestions.Youwillmostlikelyfindquestionspostedbyotherpeoplewhoarehavingthesameproblemasyou.

DIGGINGINTOTHECODE

HopefullyyounowhaveyourcodeuploadedandrunningonyourArduinoUno.Butwhatisthecodeactuallydoing?YouknowthattheArduinoUnoisturningonandofftheLEDnextto13,buthowdoesitknowtodothat?

Agreatwaytostartlearningaboutcodeisbyreadingitbeforeyouwriteit.Afterall,youdidn’tlearnhowtowriteinschoolbeforeyoulearnedhowtoread!YoucanusetheBlinkasanintroductiontocode.Don’tworryaboutunderstandingallthedetailsrightaway—it’salottolearn.Youwillbeshownabunchofnewterms,butyoudon’tneedtorememberwhattheyallmeanrightaway.Youwillgettospendmoretimeunderstandingthemintheotherchapters.

IfyoulookagainattheBlinksketchonthescreen,you’llseethatthefirstsectionisallingrey.TheArduinoIDEhelpsyouunderstandwhatishappeninginthecodebychangingthecolourofthecodeaccordingtowhatitdoes.Thetextthatturnsgreyiscalledacomment.Commentsarenotestotheprogrammertohelpexplainwhatishappeninginthecode.Thelongcommentatthetopofthesketchexplainswhatthesketchdoes:

Commentsarenoteswithinyourcodethatexplainwhatalineorsectionofcodeisintendedtodo.Eachcommentlinebeginswith//or,ifyouwanttowriteacommentthatspansmultiplelines,isbetween/*and*/.Thesespecialcharacterstellthecomputerrunningtheprogramtoignorethatlineorlines.

/*

Blink

TurnsonanLEDonforonesecond,thenoffforonesecond,

repeatedly.

MostArduinoshaveanon-boardLEDyoucancontrol.OntheUnoand

Leonardo,itisattachedtodigitalpin13.Ifyou’reunsurewhat

pintheon-boardLEDisconnectedtoonyourArduinomodel,check

thedocumentationathttp://arduino.cc

Thisexamplecodeisinthepublicdomain.

modified8May2014

byScottFitzgerald

*/

Therestofthelinesthatdon’tstartwith//arelinesofcodethatthecomputerwillexecute.Thelinesstartingwith//areignoredbythecomputerandarenotestoexplainwhatthecodeisdoing.

EveryArduinosketchhastohavetwofunctions:setup()andloop().Afunctionisasetoflinesofcodethathaveaname.Thenextsectionofcodeisthesetup()function,whichrunsonlyonceandisfortasksthatneedtohappenonlywhentheArduinoisfirstturnedon.WheneveryourArduinoUnofirststartsup,itlooksforthesectionofthesketchthatisthesetup()function,anditrunsthatsectionfirst.continuedcontinued

Afunctionisasetoflinesofcodethathaveaname.Afunctioncanbeusedoverandoveragain.Itmaytakesomeinformationasaninputandoutputmoreinformationwhenitisfinished,butnotallfunctionsneedtodothat.

//thesetupfunctionrunsoncewhenyoupressresetorpower@@ta

theboard

voidsetup(){

//initializedigitalpin13asanoutput.

pinMode(13,OUTPUT);

}

Asyoucansee,thereisonlyoneinstructioninsidethesetup()function—thefunctionpinMode().EverypinontheArduinocanreadininformationoroutputinformation,butitcan’tdobothatthesametime.ThepinMode()functionsetsupwhetherthepininputsoroutputsbytakingtwoarguments.Thefirstisthenumberofthepinyou’reusingontheArduinoboard.TheLEDontheArduinoUnoisconnectedtoPin13.Thesecondisaspecialkeyword,OUTPUT,whichtellstheArduinothatyouwanttooutputonPin13andnotreadinonthatpin.

Anargumentisapieceofinformationgiventoafunction,whichthefunctionthenusestoperformitstask.Theargumentgoesinsidethebracketsthatfollowthefunctionname.Inthefollowingcodesnippet,forexample,thefunctiondelay(1000)hastheargument1000,whichisthenumberofmillisecondsyouwanttheArduinotowaitbeforeexecutingthenextline.

TheremainingcodeintheBlinksketchistheloop()function.AftertheArduinoUnoexecutesallthecodeinthesetup()function,itlooksforafunctioncalledloop().Itthenexecutesallthecodeinthatfunction.Whenitisdone,itexecutesallthecodeintheloop()functionagain.Andthenagain!Andonandon!Theloop()functionrepeatsforever(oratleastuntiltheArduinoUnonolongerhaspower).

//thelooproutinerunsoverandoveragainforever

voidloop(){

digitalWrite(led,HIGH);//turntheLEDon

(HIGHisthevoltagelevel)

delay(1000);//waitforasecond

digitalWrite(led,LOW);//turntheLEDoff

bymakingthevoltageLOW

delay(1000);//waitforasecond

}

Thefirstlineofcodeintheloop()functionturnsontheLEDusingthefunctiondigitalWrite().Ittakestwoarguments:thepinnumberandwhetheryouareturningtheelectricityonoroff.TheargumentforthepinnumberisjustlikewhatyousawwithpinMode().Thesecondargumentisakeyword:HIGHorLOW.HIGHturnsontheelectricity,andLOWturnsitoff.

Thelastpieceofcodethatyouhaven’tlookedatisthedelay()function.TheArduinoboardrunsthiscodeveryfast—millionsoftimesasecond.That’ssofastthatyouwouldn’tbeabletoseetheLEDturnonandoff.SoyouneedtomaketheArduinopausesothatyoucanseethelightblink.ThedelayfunctionmakestheArduinowaitforthenumberofmillisecondstypedastheargument.Inthisexamplethedelayis1000milliseconds,whichisequalto1second.Here’sareviewofwhatthewholesketchdoes:

1. ThesetupfunctionusesthepinModefunctiontosetthepintheLEDisontobeanoutput.

2. Intheloop()function,theelectricityontheLED’spinisturnedon.3. TheArduinoispausedfor1000milliseconds.4. TheelectricityontheLED’spinisturnedoff.5. TheArduinoispausedfor1000milliseconds.6. Theloop()functionstartsoveragain.

Onelastdetailyoumighthavenoticedisthatcodehassomestrangepunctuation.Mostofthelinesendwitha

semicolon(;).Thisislikeafullstopattheendofasentence.Afullstopindicateswhenasentenceisfinished—itkeepswritingneatandtidy.Asemicolondoesthesamethingforacomputer.Ithelpsthecomputerseparatedifferentlinesofcode.

Youmayhavealsonoticedthatthecodehasspacesandindentation.Thesearelikecomments—theymakethecodeeasiertounderstandfortheprogrammer.Thecomputerjustignoresthem.Theindentationmakesiteasiertoseewhatlinesofcodebelongtoafunction.Youmighthavenoticedthatthelinesofcodethatbelongtoloop()areallbetween{and}andareindented.The{and}tellthecomputerthatthosearethelinesthatbelongtoloop(),whereastheindentationmakesthatmorevisuallyobvioustoreader.

Thespacesinbetweenpartsofcodearealsoonlyfortheprogrammer;thecomputerignoresthem.Forexample,delay(1000)anddelay(1000)arethesametothecomputer,butthespacescanmakeitalittleeasierforsomepeopletoreadthecode.Youcandecidehowyouprefertowriteyourcodeinthefollowingchapters!

CHALLENGE

TrychanginghowlongtheLEDturnsonandoffbychangingtheargumentsinthedelay()functions.RememberyouneedtouploadyourcodeaftereachtimeyouchangeitinorderforthesketchwiththenewchangestobeontheArduinoUno.

BuildinganLEDCircuitNowthatyouhaveanLEDblinkingontheArduinoUno,youarereadytogobeyondtheUno’sboardandbuildyourfirstcircuit!Youwillusefirstbecomefamiliarwiththetoolsyouwillusetobuildandtestnewcircuits:circuitschematicsandbreadboards.Theyarethekeystocreatingyourownprojectsthatyoucansharealongwithbeingabletobuildprojectsdesignedbyother.Inthenextchapteryouwillgoastepfurtherandbuildahousingforyourcircuit,butit’sagoodideatofirstbecomecomfortablewithhowyourcodeandcircuitcometogetherontheArduinoUno.

WhatYouNeedYouneedthefollowingthingstobuildyourLEDcircuit.Figure1-12showstheelectroniccomponentsyouneed.

AcomputerAnArduinoUnoAUSBcableAbreadboard1220Ωresistor1LED2jumperwires

FIGURE1-12Theelectroniccomponentsyouneedtobuildthecircuit

UnderstandingCircuitSchematicsElectricityistheflowofelectricalcharge.You’veseenitinnaturethroughlightningorstaticelectricitythatoccurswhenyouwalkacrossacarpetedfloorandthentouchadoorhandle.Youalsousecircuitseverydaytocontrolhowelectricityisallowedtoflow.Youturnonandoffthelightsinaroomwithalightswitch.YoucanturnonaTVandchangethechannel.Thisisalldonebyusingcircuitstocontrolelectricity.You’renotreadyyettobuildthekindofcircuitsthatareinsideaTV,butyoucanbuildacircuitthatturnsonandofflights!

Evenasimplecircuitcanbebuiltinmanydifferentways.Forexample,LEDscomeindifferentsizesandcolours.YoucouldpoweranLEDfromanArduinoUnoorwithabattery.Acircuitschematicissimplyadiagramshowingtheimportantinformationaboutacircuit,usingsymbols.Figure1-13isacircuitschematicshowingthecircuitthatyouarenowgoingtobuild.TherearethreesymbolsintheschematiceachrepresentingtheArduinoUno,theresistor(moreaboutwhatthatisalittlelater)andtheLED(thetriangularsymbol).YoucouldbuildthecircuitusingalargeredLEDorasmallgreenLED;it’syourchoice.TheimportantinformationisthatyouareconnectingthatLEDtoanArduinoUnoandaresistor.

FIGURE1-13ThecircuitschematicfortheLEDcircuit

Electricitycanbedescribedandmeasuredindifferentways.Becauseit’sinvisible,itcanbehardtoimaginehowelectricityworks,sowaterisoftenusedasananalogy.Theflowofelectricityinawireislikewaterinapipe.Thewaterflowmovingthroughthepipeissimilartotheelectricalcurrent(measuredinamps,whichisabbreviatedA),andthewaterpressureisliketheelectricalvoltage(measuredinvolts,whichisabbreviatedV).Thesize

ofthepipeincombinationwithhowmuchwaterisbeingmovedthroughitaffectsthewaterpressure.Asmallerpipecreatesmorewaterpressurethanalargerpipewhenthesameamountofwaterispassedthroughboth.Thesizeofthepipedescribesthethirdpropertyusedtodescribeelectricity:resistance(measuredinOhmsrepresentedandrepresentedwiththesymbolΩ).

Thatmayseemcomplicatedanddifficulttounderstand,butdon’tworryaboutgraspingallthedetailsnow.Byworkingwithelectricityandbuildingcircuits,you’llfigureouthowvoltage,currentandresistancearerelated.Backtothecircuitschematic!

Thestudyofelectricityandcircuitsiscalledcircuittheory.Ifyouareinterestedinlearningmoreaboutcircuittheory,therearegreattutorialsonlinetogetyoustarted.IreallylikeSparkfun’s.Theyhaveanimationstohelpillustratetheconcepts!Startwithhttps://learn.sparkfun.com/tutorials/what-is-electricityandhttps://learn.sparkfun.com/tutorials/voltage-current-resistance-and-ohms-law.

IntheschematicinFigure1-13,thecircuitisconnectedtoPin13andGNDontheArduino.Pin13iswheretheelectricitythatlightsuptheLEDflowsfrom.GNDstandsforgroundor0V.Whenyouuseabatterytopoweracircuit,thebatteryhastwoterminals:positiveandnegative.Electricityflowsfromthepositivetothenegative.Pin13andGNDontheArduinoUnoplaythesameroleasthepositiveandnegativeterminalsofthebattery.ElectricityflowsfromPin13toGNDwhentheyareconnectedinacircuit.

ThecircuithastwocomponentsbesidestheArduinoUno:aresistorandanLED.ThepinsontheArduinoUnoalloutput5V,whichistoomuchfortheLED.Rememberthewateranalogy?ThinkoftheLEDlikeadrinkingstraw.It’snotasstrongasapipe,soforcingtoomuchwaterintoitcancausethestrawtoburst.AresistorhelpstocontrolhowmuchcurrentcanflowthroughtheLED.Inthiskindofcircuit,theresistorlimitstheamountofcurrent,soisknownasacurrent-limitingresistor.

Aresistorisanelectricalcomponentthatresistscurrentinacircuit.Forexample,LEDscanbedamagedbytoomuchcurrent,butifyouaddaresistorwiththecorrectvaluetotheLEDcircuittolimittheamountofcurrent,theLEDisprotected.ResistanceismeasuredinOhms(representedbyΩ).Youneedtopickaresistorwiththecorrectvaluetolimitthecurrentthroughacircuit;thevalueofaresistorisshownbycolouredbandsthatarereadfromlefttoright.

UsingaBreadboardAfteryouknowwhatcircuityouarebuilding,youneedtousesomethingcalledabreadboardtohelpyoubuildit.Abreadboardisaboardwithrowsofholesonit(seeFigure1-14).Ifyoucouldpeekinsidetheplasticcaseofthebreadboard,youwouldseethattheholesineachrowtouchthesamepieceofmetal.Stickingtwowiresinthesamerowmeanstheyaretouchingthesamepieceofmetal,andelectricitycanflowbetweenthem.

Abreadboardisareusabledevicethatallowsyoutocreatecircuitswithoutneedingtosolderallthecomponents.Breadboardshaveanumberofholesintowhichyoupushwiresandcomponentstocreatecircuits.

FIGURE1-14Abreadboardhasaseriesofholesthatareconnectedinrowswithtwopairsoflongrowsontheoutsideandshorter,perpendicularrowsinthecentreoftheboard.

Thelongrowsontheoutsideedgesoftheboardarewhereyoucanconnect5Vandground(GNDontheArduinoboard).Someboardsmaycomewithlabelslike+or-orcolourslikeredandblackorblue.Redisacolourusedtorepresentthepositivevoltage,sowiththeArduinoUnothatwouldbe5V.BlackorblueisusedtorepresentgroundorGNDontheArduinoUno.

Youcanthinkofthelongrowsfor5Vandgroundasexpansionsforthe5VandGNDpinsontheArduinoUno.Thereisonlyone5VpinontheArduinoUno,sowhatifyouhavemorethanonecomponentthatneedstoconnectto5V?Byusingajumperwire,youcanconnect5Vtoarowonthebreadboard.Youthenhavemanyholeswherecomponentscanconnectto5V.It’sthesameforground.TherearemoreGNDpinsontheArduinoUno(therearethree,andtheyalldothesamething,soyoucanuseanyofthemwheneveryouneedtoconnecttoground),butyoucanalsouseajumperwiretoexpandthenumberofgroundconnectionsonthebreadboard.Figure1-15showshowyoucandothis.

FIGURE1-15Basiclayoutofabreadboard

Therowsinthemiddleofthebreadboard,betweenthelongoutsiderows,arewhatyouusetoconnectyourcomponentstoeachother.Ifyoucouldseeinsidetheplasticcaseofthebreadboard,youwouldseethattheserowsareperpendiculartothelongrowsontheedges.Theholesareingroupsoffiveanddon’tconnectacrossthegapinthemiddleofthebreadboard.

BuildingYourFirstCircuitYouarenowreadytobuildyourLEDcircuitusingyour220-OhmresistorandLED.AnLEDisdirectional—thatmeansyoucanaccidentallyputitinacircuitbackwards.IfyoulookattheLEDclosely,youcanseethatthetwolegsaren’tthesamelength.ThelonglegoftheLEDshouldconnecttothepositiveor5Vportionofthecircuit,andtheshortlegshouldconnecttoground.Theresistorisn’tdirectional,sobothlegsarethesamelength,anditdoesn’tmatterwhichlegisconnectedtowhichpartofthecircuit.

GothroughthefollowingstepstobuildthecircuitinFigure1-16:

1. ConnectoneendofajumperwiretooneoftheGNDpinsontheArduinoandtheotherendtoalongrowonthebreadboard.ThisistheblackwireinFigure1-16,butyourjumperwirecanbeanycolour.

2. Putonelegoftheresistorintoanyoftheshortrowsinthemiddleofthebreadboard.3. Puttheotherlegintoanothershortrowinthemiddleofthebreadboard.Itjustcan’t

beinthesamegroupoffiveholesastheotherleg!4. PutthelonglegoftheLEDintoaholeinthesamerowasoneofthelegsofthe

resistor.Theyarenowtouchingthesamepieceofmetalinsidethebreadboard,soelectricitywilleventuallybeabletoflowthroughtheresistorandthenthebreadboardrowandthentheLED.

5. ConnecttheshortlegoftheLEDtothelongrowofthebreadboardwherethejumperwireisconnected.

6. UseasecondjumperwiretoconnectfromPin13tothesameshortrowasthelegoftheresistorthatisn’tconnectedtotheLED.

FIGURE1-16TheLEDcircuitonthebreadboard

Don’teverconnectthe5VandGNDpinstogetherwithoutacomponentlikearesistororLEDinbetweenthem.ThiscreatesashortcircuitandcandamageyourArduinoUno.Ifyoueverdothisby

accident,yourcomputerwillprobablynoticethatsomethingiswrongonyourArduinoUnoandwillcutoffthepowerfromthecomputertotheUno.Ifthishappens,justunplugtheArduinoUnofromthecomputerandthenplugitinagain.

YourLEDshouldnowblinkonandoffonthebreadboard,justliketheLEDdidontheArduinoboard.Congratulations!You’vebuiltyourfirstArduinocircuit!Yourcodeiscontrollingelectricityandwhetheralightisonoroff.ThisisjustthebeginningofyourjourneytobuildsomeexcitingArduinoprojects.

Visitthecompanionsiteatwww.wiley.com/go/adventuresinarduinotoseeavideoshowinghowtobuildthiscircuit.

CHALLENGE

ChangethepinnumberthatyourLEDcircuitisconnectedto.Youcanuseanyofthepinsfrom2to13onthesectionoftheboardlabeledDigital,showninFigure1-17.Theotherpinshavespecialfunctionsthatyoulearnaboutinthenextadventure.

Remember,youneedtomakeachangeinyourcode(andremembertouploadyourchangetoyourArduinoboard),andyouneedtomakeachangetothecircuit.

FIGURE1-17ThedigitalpinsontheArduinoboard.DigitalPins0and1arespecialpinsthatyoulearnaboutlater.

FurtherAdventureswithArduinoCongratulations!Youhaveachievedalot.Itmightseemlikethatwasalotofworkjusttogetasinglelighttoflashonandoff,butitmeansyouarereadyforallkindsofadventures.

Checkoutprojectsthatothershavedonetogetsomeinspirationforwhatispossible:

http://makezine.com/category/electronics/arduino/

www.creativeapplications.net/tag/arduino/

ArduinoCommandQuickReferenceTable

Command Description

setup() FunctionthatrunsoncewhentheArduinoUnofirststarts.Seealsohttp://arduino.cc/en/Reference/Setup.

loop()Functionthatisrepeatedlyrunafterthesetup()iscompletedanduntiltheArduinoisturnedoff.Seealsohttp://arduino.cc/en/Reference/Loop.

pinMode()Setsthepinnumberenteredastheargumenttoeitheroutputelectricityorreaditin.Seealsohttp://arduino.cc/en/Reference/PinMode.

OUTPUTKeywordsetinsecondargumentofpinMode()thatsaysthepinwilloutputelectricity.Seealsohttp://arduino.cc/en/Reference/Constants.

digitalWrite() Turnsonorofftheelectricityatthespecifiedpin.Seealsohttp://arduino.cc/en/Reference/DigitalWrite.

HIGHKeywordusedtoturnontheelectricityindigitalWrite().Seealsohttp://arduino.cc/en/Reference/Constants.

LOWKeywordsuedtoturnofftheelectricityindigitalWrite().Seealsohttp://arduino.cc/en/Reference/Constants.

delay()PausestheArduinoUnoforaspecifiednumberofmilliseconds.Seealsohttp://arduino.cc/en/Reference/Delay.

AchievementUnlocked:Youaremakingalltherightconnectionsandshiningbright!

IntheNextAdventureInthenextadventure,youstartaddinginteractivitytoyourArduinocodeandcontrolLEDsusingadial!

YOUNOWHAVEtheArduinosoftwareinstalledandhaveuploadedyourfirstsketchtomakesureeverythingissetupcorrectly.(Ifyouhaven’tdonethat,itwouldbebesttogotoAdventure1anddothatnow!)It’sgreattellingtheArduinotocontrolsomethinglikeflashinglights,buttherealfunwithArduinostartswhenyourprojectsbecomeinteractive.Thereareacouplethingsthatneedtohappenbeforeaprojectcanbecomeinteractive:firsttheArduinoneedstoknowsomethingaboutwhatishappeningintherealworld;thentheArduinocodeneedstodosomethingbasedonthatinformation.

You’regoingtotravelalongwayinthisadventure!YoustartbycontrollingmultipleLEDsandthenyouprintsomemessagesfromtheArduinotothecomputer.Afterthat,youreadininformationfromasensorandprintthatinformationtothecomputer.Finally,youputallofthatknowledgetogethertobuildaterrificstatusmessagesign,whichwillhavemultiplemessagesandacontrolknobyoucanturntochoosewhatmessageyouwanttodisplay—perfectforwelcomingorsendingawayvisitorsatyourwhim.

WhatYouNeedYoufirstfindouthowtoaddmoreLEDstoyourcircuitandthenhowtouseasensorcalledapotentiometer.Thefollowinglisttellsyouwhatyouneed,andFigure2-1showstheelectroniccomponents.Remember,AppendixBincludessuggestionsofwhereyoucanbuyeverything.

AcomputerAnArduinoUnoAUSBcableAbreadboard3LEDs(1green,1yellow,1red)3220Ωresistors110kΩpotentiometer4jumperwires

FIGURE2-1Theelectroniccomponentsyouneedforthefirstpartofthisadventure

AddingMoreLEDsInChapter1,youbuiltacircuitonabreadboardsothattheArduinocontrolledasingleLED.OneLEDisgreat,butmoreLEDsareevenbetter!SowhatdoyouneedtodotoaddmoreLEDs?

ThefirstthingyouneedismoreLEDs—thisadventureusesthree.Youalsoneedthree220Ωresistors,aseachLEDneedsitsowncurrent-limitingresistor.Resistorshelpcontroltheflowofelectricityinacircuit.Inthiscircuit,theresistorsprotecttheLEDsfrombecomingdamagedfromtoomuchcurrent.YoucanreadmoreaboutcurrentandresistorsinAdventure1.

StartbybuildingthecircuitshowninFigure2-2:

1. Putonelegofoneoftheresistorsinashortrowonthetophalfofthebreadboardtowardstheleftsideoftheboard.Puttheotherlegoftheresistorintheshortrowacrossthegapinthemiddleofthebreadboarddirectlybelowwhereyou’veinsertedthefirstresistorleg.Therowsofthebreadboardaren’tconnectedacrossthegap,soeachresistorlegisinitsownrow;theyaren’ttouchingthesamepieceofmetalinsidethebreadboard.

2. Repeatwiththesecondandthirdresistors.Placeoneresistorinthecentreofthebreadboardandtheothertowardstherightsideofthebreadboard.Eachresistorshouldreachacrossthegapinthemiddleoftheboardandhaveoneleginashortrowabovethegapandtheotherinashortrowbelowthegap.

3. NowaddtheLEDs.ThelonglegofeachLEDconnectstotheresistorandtheshortlegconnectstoground.InsertthelonglegofeachLEDintothesameshortrowaseachresistor.Itshouldbeplacedjustbelowtheresistor.PlacethegreenLEDontheleftsideofthebreadboard,theyellowinthemiddleandtheredontherightside.

4. InserttheshortlegofeachLEDintooneofthelongrowsrunningtheentirelengthofthebreadboardattheverybottom.Ifyourbreadboardislabelledwithablueorblacklineora-,insertthethreeshortlegsintothatrow.Ifyourbreadboardisn’tlabelledthenyoucanuseeitherrow—justmakesureallthreeofthelegsareinthesamerow.

5. Yourcircuitisnowbuiltonyourbreadboard.AllthatisleftistoconnectittoyourArduinoUno.UseonejumperwiretoconnectfromaGNDpin(therearethreeofthemontheArduinoUnoandyoucanusewhicheveryouwouldlike,theyareallthesame)tothelongrowonthebreadboardwhereyourthreeshortLEDlegsareinserted.

6. Usingthreemorejumperwires,connectonewirefromPin5ontheArduinoUno(notA5,butthe5inthesectionlabelledDigital)tothetopoftheresistorontheleftsideofthebreadboardconnectedtothegreenLED.UseasecondjumperwiretoconnectPin6tothemiddleresistorconnectedtotheyellowLED,andathirdjumperwiretoconnectfromPin7tothelastresistorconnectedtotheredLED.

FIGURE2-2BuildingacircuittocontrolthreeLEDs

Finished?Nowyou’rereadytowritethecode.It’sgoingtolookalotliketheBlinksketchdescribedinAdventure1.YouusecodetocontrolwhenanLEDturnsonandoff.ThebigdifferenceisthatyoustartusingvariablestokeeptrackoftheLEDs,andyouneedtocontrolthreeLEDsinsteadofonlyone.Youreadmoreaboutvariablesinthenextsection.

First,launchtheArduinoIDE.Itopensanewsketchwindowwhentheprogramstarts.YoucanalsogotoFile⇒NeworclicktheNewbuttontocreateanewemptysketch.Typeinthefollowingsketchexactlyasitiswritten.Thespacesandindentationaren’timportant;theyjustmakethecodeeasiertoread.However,don’taccidentallyleaveoffa;oryourcodewon’trun!Don’tforgettosaveitbygoingtoFile⇒SaveorclickingtheSavebutton.//Pins

intgreenLED=5;

intyellowLED=6;

intredLED=7;

voidsetup(){

//settooutputtoLEDpins

pinMode(greenLED,OUTPUT);

pinMode(yellowLED,OUTPUT);

pinMode(redLED,OUTPUT);

}

voidloop(){

//turnonallLEDs

digitalWrite(greenLED,HIGH);

digitalWrite(yellowLED,HIGH);

digitalWrite(redLED,HIGH);

//wait1second

delay(1000);

//turnoffallLEDs

digitalWrite(greenLED,LOW);

digitalWrite(yellowLED,LOW);

digitalWrite(redLED,LOW);

//wait1second

delay(1000);

}

Typingthesketchesbyhandisagoodwaytobecomemorecomfortablewithallthenewcodingtermsyouarelearning,butitcanbefrustratingifit’sareallylongsketchoryou’vemadeatypothatyoucan’tfind.Forthosecases,allthesketchesareavailabletodownloadfromcompanionsitewww.wiley.com/go/adventuresinarduino.

Afteryouhavefinishedtypingoutthesketchandhavesavedit,youarereadytouploadittoyourArduinoUno.Selecttheboardandportfromthemenus(youcanreviewhowtodothisinAdventure1).ClicktheUploadbuttonandwatchformessagestoappearatthebottomofthewindowoftheArduinoIDE.

Iftherearen’tanyerrors,yourthreeLEDsshouldstartflashingonandoff!That’ssomuchmoreexcitingthanblinkingjustoneLED.

Ifyouseeanyerrorsthatsay“Expectedinitializerbefore'void'”or“expected';'…”thenyouprobablyhaveatypo.Lookcarefullyoveryourcodeandmakesureitmatcheswhatyouaresupposedtotypein.Ifthereareanyerrorsfromavrdude,checkthatyourArduinoUnoispluggedintoyourcomputerandthatyou’vechosenthecorrectoptionsfromtheBoardandPortmenus.Ifyoustillhaveproblems,gobackthroughAdventure1tomakesureyoursoftwareisinstalledcorrectly.

DIGGINGINTOTHECODE

Nowthatyouhaveseenwhatthecodedoes,it’stimetofigureouthowit’sdoingthat!Thesketchcanbebrokenupintothreesections:thelinesbeforethefunctions;thesetup()function;andtheloop()function.

First,thelinesofcodebeforethefunctions.

//Pins

intgreenLED=5;

intyellowLED=6;

intredLED=7;

Thefirstlinebeginningwith//isacommentexplainingwhatthefollowinglinesmean.ThenextthreelinesarevariablesassignedthepinnumbersforeachoftheLEDs.Avariableislikegivingsomethingincodeaname.Hereit’sgivinganametothepinnumberstomakeiteasiertorememberwhichLEDisconnectedtoeachpin.ThenamegreenLEDismuchmoreobviousthatthenumber5,isn’tit?

Avariableisacodeconstructthatholdsavaluethatcanbechanged.Forexample,thevariablegreenLEDstoresthenumber5.

Infrontofeachofthevariablenamesisint.Thisisdescribingwhatkindofdatacanbestoredinthevariable.intisshortforinteger,sothevariablescanstoreonlywholenumbers.

Althoughgivingsomethinganameisconvenient,variablesbecomereallypowerfulwhenthevariablechangesitsvaluebutkeepsthesamename.Thatfeatureofvariablesisn’tbeingusedhere,butitisinthenextsection.

Thereafewrulestokeepinmindwhencreatingnewvariablenames.Thefirstisthattheycan’thavespacesinthem,butyoucanuseunderscores(greenLEDandgreen_LEDarefine,butgreenLEDisnot).Youalsocan’tstartthenamewithanythingbesidesaletter(led3isfine,3ledisnot).Lastly,it’snotarequirement,butvariablesusuallystartwithalowercaseletter(greenLEDratherthanGreenLED).

Thenextpartofthesketchisthesetup()function.ThisfunctioniswhattheArduinoUnorunsrightwhenitstartsup.Itisonlyrunthatonetime,sothisfunctionisforcommandsthatneedtobedoneonlyonce.Themostcommonthingdoneinthesetup()istosetthepinMode()ofpinsbeingused.ThepinMode()determineswhetherthepinwilloutputelectricitytocontrolacomponentlikeanLEDoritwillreadinasignalfromasensor.

Thiscircuitdoesn’thaveanysensors—onlyLEDs—sothepinMode()issettoOUTPUTforeachofthepins.Becausevariablesarebeingusedtorepresentthepinnumbers,theirnames(greenLED,yellowLEDandredLED)canbetypedinsteadof5,6and7.

voidsetup(){

//settooutputtoLEDpins

pinMode(greenLED,OUTPUT);

pinMode(yellowLED,OUTPUT);

pinMode(redLED,OUTPUT);

}

Thefinalsectionofcodeistheloop()function.ThisfunctionisexecutedrepeatedlyuntiltheArduinoUno’spowerisremoved.

Theloop()functionusesonlytwootherfunctions:digitalWrite()anddelay().ThedigitalWrite()functionturnsonoroffanLED.ThefirstargumentdetermineswhichLEDisbeingtalkedabout,andthesecondargument

determineswhatistobedone—eitherturnontheLEDiftheargumentisHIGHorturnitoffiftheargumentisLOW.

Tosummarisewhattheloop()does,itturnsoneachLED,thenwaitsfor1secondsoyoucanseethemon,thenitturnsoffeachLEDandwaitsfor1secondsoyoucanseethattheyareoff.

voidloop(){

//turnonallLEDs

digitalWrite(greenLED,HIGH);

digitalWrite(yellowLED,HIGH);

digitalWrite(redLED,HIGH);

//wait1second

delay(1000);

//turnoffallLEDs

digitalWrite(greenLED,LOW);

digitalWrite(yellowLED,LOW);

digitalWrite(redLED,LOW);

//wait1second

delay(1000);

}

CHALLENGE

NowyouhavethreeLEDsthatallblinktogether,makethemlightupinasequenceonebyone.Youwon’tneedtochangethecircuit;youchangeonlythecode.RemembertouploadyourchangesinyourcodetotheArduinoUno.

Afewhints:

Youdon’thavetowritemoredigitalWrite()functions;youonlyneedtomovearoundtheonesalreadywritten.Youneedtoaddmoredelay()functions.

PrintingMessagestotheComputerAfteryouuploadcodeontotheArduinoUno,theboarddoesn’ttalktothecomputer.Infact,itdoesn’tneedthecomputeratall.Theonlythingthat’shappeninghereisthattheArduinoUnoisgettingitspowerfromthecomputer,viatheUSBcablepluggedintothecomputer.Youcouldevenunplugitfromthecomputeranduseabattery.(YoucanfindinformationaboutpoweringtheboardwithabatteryinAdventure5.)ButyourcomputercanstillbeusefulafteryouhaveuploadedyoursketchontotheArduinoUno.Forexample,theArduinoUnodoesn’thaveascreen,butthecomputerdoes.Soifyouaredebuggingyourcode,orjustwanttoreadmessagestoknowwhattheboardisdoing,thecomputerandUSBcablecanbeapowerfultool.

Debuggingisthewhereyoulocatethecauseofanyerrorsinyourcomputerprogramcodeandfixthem.

TheArduinoUnocantalkwiththecomputerusingserialcommunicationovertheUSBcable.Thisjustmeansthatonebitofdataissentatatime.Youcanthinkofitasoneletterofawordbeingsentatatime,eventuallytospelloutawholeword.TosenddatafromtheArduinotothecomputer,therearejustthreefunctionsyouneedtoknowabout.

Serialcommunicationisonewaythattwodevices,likeacomputerandanArduinoboard,cansendandreceivedatatoeachother.Onepieceofdataissentatatime.

Thefirstfunctionisonethatyouonlyneedtocallonceinthesetup()function:Serial.begin(9600);

Thisfunctiontakesonlyoneargument:thespeedatwhichtheArduinoUnoissendingoutandreceivingdata.It’simportantthatthisnumberisthesameasthespeedthatthecomputerissendingandreceivingdata(youfindouthowtocheckthatlater).IfthecomputerandArduinoUnoaresendingandreceivingdataatdifferentspeeds,theywon’tbeabletounderstandeachother.Unlessyouareexplicitlytoldtouseadifferentnumber,9600isagoodnumbertouse.

Rememberthatyoucanalwayslookuptermsintheglossaryatthebackofthebook.

Theothertwofunctionsare:Serial.print("Yourmessagegoeshere");

Serial.println("Yourmessagegoeshere");

ThesearethefunctionsthatsendmessagesfromtheArduinoboardtothecomputer.The

firstone,Serial.print(),doesn’tsendanewlinecharacterattheendofthemessage;inotherwords,thecursorisn’tmoveddowntothenextlineattheendofthemessage.ThefunctionSerial.println()doesincludeanewline;youcanimaginethisasamessagewithanEnterattheendofit.

AnewlinecharacterislikepressingtheEnterorReturnkeyonyourkeyboard.

Thebestwaytounderstandthisistotryitout.There’snocircuitforthis;youjustneedtheArduinoboardpluggedintoyourcomputer.Createanewsketchwiththefollowingcodeanduploaditontotheboard:voidsetup(){

//tostartserialcommunication

//theargumentneedstomatch

//therateyouchooseinthe

//SerialMonitor

Serial.begin(9600);

Serial.println("Hello,thisisfromsetup");

//adelaysothatmessagesaren’ttooquicktoread

delay(3000);

}

voidloop(){

//printingamessageandthenwaitingasecond

Serial.print("Thisisfromloop,withaprint.");

delay(1000);

Serial.println("Andthisisfromloopwithaprintln.");

delay(1000);

intmyVariable=27;

Serial.print("Andthisisprintingavariable:");

Serial.println(myVariable);

delay(1000);

}

YoumayhavenoticedthatthemessagesyousendinSerial.print()andSerial.println()arebetweenquotationmarks("").Thisishowyouwriteincodeapieceoftextthatyoudon’twantthecomputertointerpretascode.Youcanprintthevalueofavariablebyreplacingthemessageandthe""withavariablename,suchasthevariablemyVariableinthesketch.

Afterthesketchisuploadedontotheboard,opentheSerialMonitorbyclickingthatlastArduinoIDEbutton—theoneIdidn’tcoverinAdventure1.It’sthebuttononitsownontherightinFigure2-3.Afteryouclickthebutton,awindowopensliketheoneshowninFigure2-4.Youmaynoticethatthenumber9600appearsinthebottomrightofthewindow(ifitdoesn’tyoushouldclickthenumberthatisthereandselect9600).ThisisthenumberthatneedstomatchtheargumentinSerial.begin()inyourArduinocode.

FIGURE2-3TheSerialMonitorbutton

FIGURE2-4TheSerialMonitorintheArduinoIDE

YouwillseethemessagesfromyourArduinoUnoappearinyourSerialMonitor.TheSerialMonitorisatoolbuiltintotheArduinoIDEthatletsyouseethemessagessentbytheArduinoUnousingserialcommunication.Youwillfinditaveryusefultoolinallofyouradventures!WhenyouaredonewiththeSerialMonitor,youcanjustclosethewindow.Itmayalsocloseonitsownwhenyouuploadanewsketchtoyourboard.YoucanreopentheSerialMonitortoseeanynewmessages.

DIGGINGINTOTHECODE

Sowhat’sgoingoninthecode?Therearethesectionsthatyouareprobablygettingusedto:thesetup()andloop()functions.Thesetup()functiondoesn’thavemuchgoingon.Thefirstfourlinesarecommentsexplainingwhatishappening.Theserialcommunicationisthenstartedandamessageissent:Hello,thisisfromsetup.TheArduinoUnoisthenpausedfor3seconds,justsothatmessagesdon’tprinttoofasttoread.

voidsetup(){

//tostartserialcommunication

//theargumentneedstomatch

//therateyouchooseinthe

//SerialMonitor

Serial.begin(9600);

Serial.println("Hello,thisisfromsetup");

//adelaysothatmessagesaren’ttooquick toread

delay(3000);

}

Theloop()functionthenprintsmessagesinthreedifferentways.ItfirstusesSerial.print()toprintThisisfromloop,withaprint.andthenwaitsfor1second.BecausethemessageusedSerial.print()andnotSerial.println(),thenextmessageappearsonthesameline,withthenewmessageprintingrightafterthepreviousone.There’sanother1-seconddelayandthenanewvariableiscreatedtoholdthenumber27.ASerial.print()functionprintsamessageandthenthevariableprintsattheendoftheline.Becausethevariableisprintedwithoutthesurroundingquotationmarks(not"myVariable"),thenumber27isprinted.

voidloop(){

//printingamessageandthenwaitingasecond

Serial.print("Thisisfromloop,withaprint.");

delay(1000);

Serial.println("Andthisisfromloopwithaprintln.");

delay(1000);

intmyVariable=27;

Serial.print("Andthisisprintingavariable:");

Serial.println(myVariable);

delay(1000);

}

Thesetup()functionisrunoncewhentheArduinoUnoisfirstturnedon,buttheArduinoUnocallsthesetup()functionacoupleothertimesbesideswhenitisfirstturnedon.Forexample,there’saresetbuttonontheboardthatyoucanusetomanuallyrestarttheboard,sothesetup()functioniscalledbeforegoingontotheloop()function.Also,wheneveranewserialconnectionismade,theboardrestarts.SowheneveryouopentheSerialMonitor,theArduinoboardrestartsandrunsthesetup()functionagain.YoumaynoticethishappeningwhenyouopentheSerialMonitor.Themessagebeingprintedgetsinterrupted,andthemessageinthesetup()functionstartsprintinginstead.TryopeningtheSerialMonitorandthenpressingtheresetbuttonontheArduinoUno.

ReadingDatafromaPotentiometerNowyou’rereadytotakeaphysicalactionintherealworldanduseittomakedecisionsincode.ThisisexactlywhattheArduinowasbuilttodo!YouwillsoonbeturningaknobtochangewhatLEDison.

You’regoingtostartbyusingapotentiometer.That’sabignameforasimplecomponent!It’ssimplyaresistorthatadjustshowmuchresistanceithasasyouturnacontrolknob—forexample,theknobyouuseonastereototurnupthevolume.Potentiometerscomeinlotsofshapesandsizes.Figure2-5showsafewpotentiometersthatchangetheirresistancethrougharotatingmotion.Thetwobiggeronescanhaveknobsordialsthatfitovertheendoftheshafts.Thelittleoneissometimescalledatrimpot,anditalreadyhasasmallknobattachedthatyouturn.TrimpotsliketheoneshowninFigure2-5workwellwhenbuildingcircuitsonbreadboardsastheyfitintothebreadboardholes.LargerpotentiometersliketheoneontherightinFigure2-5canalsofitintobreadboards.Potentiometersliketheoneinthemiddleareeasierforsolderingwiresto.

Apotentiometerisatypeofresistorwithanadjustableknobtovarytheresistanceofcurrent.

FIGURE2-5Differentpotentiometers

Visitthecompanionsiteatwww.wiley/go/adventuresinarduinotowatchavideoshowingdifferenttypesofpotentiometers.

ThecircuittoconnectthepotentiometertotheArduinoinvolvesthreeconnections.Youcanthinkofthepotentiometerashavingtwokindsofpins:apairofoutsidepinsandaninsidepin.TheinsidepiniswhatisconnectedtoanAnaloguePinontheArduino.TheAnaloguePinsarethesectionofpinsyouhaven’tyetused(seeFigure2-6).TherearesixpinsintotalandtheyeachstartwiththeletterA(A0,A1,A2,A3,A4andA5).

FIGURE2-6AnaloguepinsontheArduinoUno

It’stimetobuildyourfirstcircuitwithapotentiometer!GothroughthefollowingstepstobuildthecircuitinFigure2-7:

1. Useajumperwiretoconnect5VontheArduinoUnotooneofthelongrowsrunningalongthebottomofthebreadboard.Ifthebreadboardislabelledwitharedlineor+,connect5Vtothatrow;otherwise,chooseeitherrow.

2. UseanotherjumperwiretoconnectGNDontheArduinoUnototheotherlongrowonthebreadboard.

3. Insertthelegsofthepotentiometerintoanyoftheshortrowsinthemiddleofthebreadboard.

4. Useajumperwiretoconnectoneoftheoutsidelegsofthepotentiometertothelong

rowconnectedtoGNDontheArduinoUno.5. Useanotherjumperwiretoconnecttheotheroutsidelegsofthepotentiometertothe

longrowconnectedto5VontheArduinoUno.6. ConnectthemiddlelegofthepotentiometertopinA0ontheArduinoUno.

FIGURE2-7Circuitforconnectingapotentiometer

YoucanreadinavaluecomingfromthepotentiometerthatcorrespondstothepositionoftheshaftorknobonthepotentiometerandprintittotheSerialMonitor.Todothis,gotoFile⇒Examples⇒01.BasicsandopenthesketchAnalogReadSerial.ThenuploadthesketchtoyourArduinoUno(rememberingtosettheboardandportasyoudidinAdventure1andearlierinthisadventure).

Whenyou’vefinished,clicktheSerialMonitorbuttontoopentheSerialMonitor.Rotatethepotentiometerallthewaytotheleftandthenallthewaytotheright.YoushouldseenumbersdisplayedintheSerialMonitor,rangingfrom0atoneendto1023attheother.ThesearetheminimumandmaximumnumbersthattheArduinocanreadinfromananaloginput.Whenthenumberis0,thepinisreadinginground(0V).Whenit’s1023,itmeansthatthepinisreadingin5V.Anynumberinbetweenmeansthatitisreadinginavoltagethat’ssomewherebetweengroundand5V.5VisthemaximumvoltagethattheArduinoUnooutputsand0Vistheminimum,sothiscircuitmeasureswhetherthepotentiometerisallthewaytotheleftorrightbymeasuringwhetherthevoltagethepotentiometerisoutputtingisthemaximum,minimumorsomethinginbetween.

DIGGINGINTOTHECODE

Sowhatishappeninginthecode?There’sonelineofcodeintheAnalogReadSerialsketchthatyouhaven’tseenbefore:

intsensorValue=analogRead(A0);

Thislinereadsinthevalue(orvoltage)beingoutputbythepotentiometercircuittoPinA0usingthefunctionanalogRead().Thisfunctiongivesyounumberbetween0and1023.Youneedtosavethisvalueintoavariablesothatyoucandosomethingwiththisnumberlater.Anewvariable,sensorValue,iscreated,andthenumberthatanalogRead()readsinissavedinthatvariable.ThatvariableisthenprintedtotheSerialMonitor.

YoumighthavealreadynoticedthatArduinousesAmericanspellingsforwordslike“analog.”It’simportanttorememberthisasanArduinoUnodoesn’tknowwhatanalogueRead()means,onlyanalogRead().

CHALLENGE

Switchtheoutsidepinsonthepotentiometersothattheonethatwasconnectedto5Visnowconnectedtoground,andtheonethatwasconnectedtogroundisnowconnectedto5V.Youdon’tneedtochangeanyoftheArduinocode.

Whatchangeswhenyouhavethecircuitsetupthiswayasopposedtohowit’swiredinFigure2-7?

MakingDecisionsinCodeTobuildinteractiveprojects,youneedtobeabletotakeinputfromtherealworldandthenhavetheArduinoUnodowhatyouwantaccordingtothatinput.Thatmeansyouneedtousecodetomakedecisionsbasedonincominginformationfromsensors.Forexample,ifyouwerebuildingaburglaralarm,youwouldwanttosoundthealarmonlyifthealarmeddoorwasopen,soyouneedtoknowhowtoexplainthatincode.

Computersworkbyansweringyesornoquestions.Thoseyesornoquestionsneedtobephrasedlikethis:

Is3greaterthan5?Is10equalto10?Is4lessthanorequalto8?

Writtenincode(sothatthecomputerunderstandsit)thesequestionswouldlooklikethis:3>5

10==10

4<=8

ThecomputerorArduinoUnocanthendodifferentthingsbasedonwhethertheanswertothequestionisyesorno(ortrueorfalse).Itdoesthisbyusingifstatements.Iftheanswertothequestioninthe()isyes,thenthecodebetweenthe{and}isexecuted:if(a<b){

//thenexecutethecodeinhere

}

Iftheanswerisno,thenthecodeinthe{}isskipped.

Forexample,thefollowingcode:if(3<5){

Serial.println("Thestatementistrue.");

}

Serial.println("Thisisaftertheifstatement.");

wouldprintthefollowing:Thestatementistrue.

Thisisaftertheifstatement.

Butthefollowingcode:if(3<1){

Serial.println("Thestatementistrue.");

}

Serial.println("Thisisaftertheifstatement.");

wouldprint:Thisisaftertheifstatement.

It’salwayseasiertounderstandanewconceptbybuildingsomethingyourselfandseeinghowitworks.Inthenextsection,you’regoingtouseifstatementsinaprojecttocreatea

statusmessagesign.

BuildingaStatusMessageSignHaveyoueverseenarecordingstudio,eitherinreallifeoronaTVprogramormovie?Thereisusuallyasignontheoutsideoftheroomthatsays“RECORDING”thatlightsuptoletpeopleknownottoenterbecausethere’sarecordingsessioninprogress.

Youaregoingtobuildyourownsignthatletsotherpeopleknowwhethertheycanenter,knockfirstorstayout.(Ifyoudon’twanttousethesignssuggestedhere,feelfreetomakeupthreedifferentmessagesthatareentirelyyourown.)EachmessagehasanLEDnexttoit.ThelightedLEDindicateswhichmessageistheactiveone.Yousetwhichmessageyouwanttobeactivewithacontrolknobonthesideofthesign,asshowninFigure2-8.

FIGURE2-8Astatusmessagesign

WhatYouNeedForthisadventureyoubuildyourfirstprojectwithitsownhousing.Youneedthefollowingtoolsandmaterialstofirstbuildandtestthecircuitonabreadboardandthenalsothetoolsandmaterialstobuildthecompleteproject.Figure2-9showstheelectroniccomponentsthatyouneed.

AcomputerAnArduinoUnoAUSBcableAbreadboard3LEDs(1green,1yellow,1,red)3220Ωresistors110kΩpotentiometer8jumperwiresSomewireSomeelectricaltapeSomesolderAshoeboxorothersmallboxPaperorpainttodecoratetheboxScissorsorautilityknifeAsolderingironWirecuttersWirestrippersUSBpowersupply(optional)

FIGURE2-9Theelectroniccomponentsyouneedtomakeastatusmessagesign

UnderstandingtheCircuitAssoonasyoustartsolderingandgluingmaterialstogether,ifyoumakeasmallmistakeitcanbedifficulttoundo.There’sawayaroundthis:beforeyoucreateyourfinishedcircuit,youshouldalwaysmakeaprototypeofitonabreadboardfirst,tomakesurethecircuitworksproperly.Thatway,ifyoumakeanymistakesinyourdesignyoucaneasilycorrectthembeforeyouhavethecomponentspermanentlyinplace.

Figure2-10showsthecircuitthatyou’regoingtobuildforyoursign.YouwillbebuildingacircuitwiththreeLEDsandonepotentiometer.TheLEDswillbeconnectedtoPins5,6and7,andthepotentiometerwillbeconnectedtoground,PinA0and5V.

FIGURE2-10Circuitschematicforthesign

YouarenowgoingtotestthecircuitandtheArduinocodeonthebreadboard,thenyouwillrebuildthecircuitwithoutabreadboard.

PrototypingonaBreadboardTobuildyourprototypecircuit,usethefollowingsteps:

1. Useajumperwiretoconnect5VontheArduinoUnotooneofthelongrowsrunningalongthebottomofthebreadboard.Ifthebreadboardislabelledwitharedlineor+,connect5Vtothatrow;otherwise,chooseeitherrow.

2. UseanotherjumperwiretoconnectGNDontheArduinoUnototheotherlongrowonthebreadboard.

3. Insertthelegsofthepotentiometerintoanyoftheshortrowsinthemiddleofthebreadboard.

4. UseajumperwiretoconnectoneoftheoutsidelegsofthepotentiometertothelongrowconnectedtoGNDontheArduinoUno.

5. Useanotherjumperwiretoconnecttheotheroutsidelegsofthepotentiometertothelongrowconnectedto5VontheArduinoUno.

6. ConnectthemiddlelegofthepotentiometertopinA0ontheArduinoUno.7. Putonelegofoneoftheresistorsinashortrowonthetophalfofthebreadboard

towardstheleftsideoftheboard.Puttheotherlegoftheresistorintheshortrowacrossthegapinthemiddleofthebreadboarddirectlybelowwhereyou’veinsertedthefirstresistorleg.Therowsofthebreadboardaren’tconnectedacrossthegap,soeachresistorlegisinitsownrow—theyaren’ttouchingthesamepieceofmetalinsidethebreadboard.

8. Repeatwiththesecondandthirdresistors.Placeoneresistorinthecentreofthebreadboardandtheothertowardstherightsideofthebreadboard.Eachresistorshouldreachacrossthegapinthemiddleoftheboardandhaveoneleginashortrowabovethegapandtheotherinashortrowbelowthegap.

9. NowaddtheLEDs.ThelonglegofeachLEDconnectstotheresistor,andtheshortlegconnectstoground.InsertthelonglegofeachLEDintothesameshortrowaseachresistor.Itshouldbeplacedjustbelowtheresistor.PlacethegreenLEDontheleftsideofthebreadboard,theyellowinthemiddleandtheredontherightside.

10. InserttheshortlegofeachLEDintothelongrowsrunningtheentirelengthofthebreadboardattheverybottomthatisconnectedtoGNDontheArduinoUno.

11. Usingthreemorejumperwires,connectonewirefromPin5ontheArduinoUno(notA5,butthe5inthesectionlabelledDigital)tothetopoftheresistorontheleftsideofthebreadboardconnectedtothegreenLED.UseasecondjumperwiretoconnectPin6tothemiddleresistorconnectedtotheyellowLEDandathirdjumperwiretoconnectfromPin7tothelastresistorconnectedtotheredLED.

Whenfinished,yourprototypecircuitshouldlookliketheoneinFigure2-11.Noticeanything?Thefullcircuitforthesignisacombinationofthetwocircuitsyouwereworkedwithearlierinthischapter.ThepotentiometerisreadintoPinA0,andthethreeLEDsarecontrolledbytheoutputonPins5,6and7.

FIGURE2-11Prototypecircuitonthebreadboardforthesign

WritingtheCodeNextyouneedthecode.LaunchtheArduinoIDEandtypethefollowingsketchinanewsketchwindow.Don’tforgettosaveit!

Startyoursketchbycreatingemptysetup()andloop()functions.voidsetup(){

}

voidloop(){

}

Nextaddavariableatthetopofthesketchtokeeptrackofyourpotentiometer.//Pins

intpotPin=A0;

Inthesetup(),startserialcommunicationsoyoucanprintmessagestoSerialMonitor.Typethefollowinglinesbetweenthe{and}ofthesetup().//startserial

Serial.begin(9600);

Theloop()functioncontrolsalltheaction.ThevaluefromthepotentiometerisreadandsavedinavariablecalledpotValue.AdifferentmessageisthenprintedaccordingtothenumbersavedinthepotValuevariable.ThemessageprintsoutwhatshouldhappenwiththeLEDs.Typethefollowinglinesbetweenthe{and}oftheloop().intpotValue=analogRead(potPin);

//printwhatthepotvalueis

Serial.print("Potentiometeris:");

Serial.println(potValue);

//ifpotislessthan341

if(potValue<341){

Serial.println("Turnongreen,turnoffyellowandred");

}

//ifpotmorethanorequalto341and

//lessthan682

if(potValue>=341&&potValue<682){

Serial.println("Turnonyellow,turnoffgreenandred");

}

//ifpotmorethanorequalto682

if(potValue>=682){

Serial.println("Turnonred,turnoffgreenandyellow.");

}

//Apausetoslowdownthemessages

delay(50);

SavethesketchanduploadittoyourArduinoUno.OpentheSerialMonitorandseewhathappenswhenyouturnthepotentiometer.Youshouldseethevalueofthepotentiometer

printalongwithwhattheLEDsshouldbedoing—butyouhaven’tprogrammedtheLEDsyet.Timetodothatnow!

AddthreemorevariablestokeeptrackoftheLEDpinsatthetopofyoursketch.intgreenLED=5;

intyellowLED=6;

intredLED=7;

Insidesetup(),addthecodetoseteachpinMode().//settooutputtoLEDpins

pinMode(greenLED,OUTPUT);

pinMode(yellowLED,OUTPUT);

pinMode(redLED,OUTPUT);

Intheloop(),addthedigitalWrite()functionstoturnonandoffeachLED(showninboldinthefollowingcode).Youcanalsoremovethedelay()attheendoftheloop().Yourfullsketchshouldlooklikethis://Pins

intpotPin=A0;

intgreenLED=5;

intyellowLED=6;

intredLED=7;

voidsetup(){

//settooutputtoLEDpins

pinMode(greenLED,OUTPUT);

pinMode(yellowLED,OUTPUT);

pinMode(redLED,OUTPUT);

//startserial

Serial.begin(9600);

}

voidloop(){

intpotValue=analogRead(potPin);

//printwhatthepotvalueis

Serial.print("Potentiometeris:");

Serial.println(potValue);

//ifpotislessthan341

if(potValue<341){

Serial.println("Turnongreen,turnoffyellowandred");

//turnongreenLED

digitalWrite(greenLED,HIGH);

//turnoffyellowandredLEDs

digitalWrite(yellowLED,LOW);

digitalWrite(redLED,LOW);

}

//ifpotmorethanorequalto341and

//lessthan682

if(potValue>=341&&potValue<682){

Serial.println("Turnonyellow,turnoffgreenandred");

//turnonyellowLED

digitalWrite(yellowLED,HIGH);

//turnoffgreenandredLEDs

digitalWrite(greenLED,LOW);

digitalWrite(redLED,LOW);

}

//ifpotmorethanorequalto682

if(potValue>=682){

Serial.println("Turnonred,turnoffgreenandyellow.");

//turnonredLED

digitalWrite(redLED,HIGH);

//turnoffgreenandyellowLEDs

digitalWrite(greenLED,LOW);

digitalWrite(yellowLED,LOW);

}

}

Uploadthesketchwiththecircuitonthebreadboard.Ifyoudon’twanttotypeallthecode,youcandownloadthesketchfromthecompanionsiteatwww.wiley.com/go/adventuresinarduino.

Ready?Timetotryitout.YoushouldbeabletochangewhichLEDturnsonbyturningthepotentiometer.OnlyoneLEDshouldturnonatatime.YoucanopentheSerialMonitorintheArduinoIDEtomakesurethecorrectvaluesarecomingfromthepotentiometer.

DIGGINGINTOTHECODE

Thereisonebitofcodeinthesketchforthestatusmessagesignthatyouhaven’tseenbefore:&&.Thosetwoampersands(&&)withoutaspaceinbetweenmeansthatboththepieceofcodebeforeitandafterneedtobetrue.

Forexample:

4<6&&10<20

istruebecauseboth4<=6and10<20aretrue.But:

3>9&&5<7

isfalsebecauseonly5<7istrue;3>9isfalse.The&&symbolisawaytocombinerestrictionsinanifstatement.Inyoursketch,it’susedtoturnontheyellowLEDonlyifpotValue>=341andalsopotValue<682.

CreatingyourSignInanyproject,thethingthatreallybringsitcometolifeisthestructureinwhichyouhousetheelectronics.Itdoesn’tjustprotectyourelectronicsandhidethepartsyoudon’twanttosee—italsogivesyouachancetogetcreative.ThecodeandcircuitareabigpartofthecreativeprocessofmakinganArduinoproject,ofcourse!Butthisisthepartwhereyoucanreallyletyourimaginationrunriotsoyoucanshowoffyourprojecttoyourfriendsandfamilybygettingitoffthebreadboardandintoastylishnewhome!

Youcanchoosewhatevermaterialsyouwouldliketousetocreateyoursign,butashoeboxworkswell.Itcaneasilybecutwithautilityknifeorscissorsanddecoratedwithpaperandglueorpaint,andyou’llbeabletomakeitaspersonalasyoulike.

Youcanwatchavideodemonstratinghowtobuildthesignandsolderthecircuitonthecompanionsiteatwww.wiley.com/go/adventuresinarduino.

CuttingHolesforthePotentiometerandLEDsBeforeyoudecoratethebox,youneedtocutsomeholesinitwhereyouwantyourLEDsandtheknobofthepotentiometertobelocated.Makefiveholes:threefortheLEDs,onefortheknobandonefortheUSBcable.MeasurethelensesoftheLEDsandtheshaftofthecontrolknobsoyoucanmaketheholesjustbigenoughforthosecomponentstofitsnuglyintothem.(Ifyoumaketheholestoobig,theLEDsandknobwilljustfallout!)FortheUSBcable,theholeneedstobelargeenoughforyoutopasstheendoftheUSBcablethatplugsintotheArduinothroughit.

Ifyouareusingashoebox,IrecommendthatyoumaketheholesfortheLEDs,knob,andUSBcableinthebottomofthebox,asshowninFigure2-12.Thatwayyoucaneasilyremovethelidtoaccesstheelectronicsandthenquicklyhidethemallaway.

FIGURE2-12CuttingholesfortheLEDsandknob

AddingtheStatusMessagesandDecoratingtheSignNowyou’rereadytotransformyouroldshoeboxintoaslicksignboxbypaintingitorcoveringitwithpaper.Decideonyourmessages—youcanusethemessagesI’vesuggestedinFigure2-11orcreateyourown.Itdoesn’tmatterwhetheryouwriteorpaintthemontotheboxyourself,printthemfromacomputerandgluethemnexttotheLEDs,cutthemoutofmagazines—dowhateveryoulike.Therearenolimits!Expressyourcreativity—usepaint,markers,crayonsorwhateveryouhaveavailable.Inmyopinion,youcanseldomgowrongwithglitter.Orwhynotusenaturalmaterialslikefeathersordriedflowers?

SolderingtheCircuitYouknowthatyourcodeandcircuitwork(andifyouhaven’ttestedthem,gobackanddothat!),soyouarereadytomorepermanentlyassembleyourcircuit.Circuitsdependonelectricityflowingthroughconductivematerialslikemetal.Thatmeansyoucan’tusethingslikegluetoconnectcomponents—theelectricitycan’tflowthroughglue.Insteadyouusesolder.It’slikeconductiveglue.

Solderisametalthatmeltsatalowertemperaturethanmostmetals,butthatlowertemperatureisstillquitehot!Muchhotterthantheoveninyourkitchenevergets,soit’simportantthatyouaresafewhensoldering.Takeasmuchcareasyouwouldhandlinghotpotsandpanswhencooking.

Onlysolderwhenanadultisnearbytohelp!

Therearelotofresourcesonlinetohelpyougetstartedsolderingifyouhaven’tdoneitbefore.YouTubeisfullofvideos,butthetutorialsonSparkfun(https://learn.sparkfun.com/tutorials/how-to-solder---through-hole-soldering)andAdafruit(https://learn.adafruit.com/adafruit-guide-excellent-soldering)areexcellentplacestostart.

Solderingcangetdifficultwhenyoufeellikeyou’verunoutofhandstoholdthings.Youcangetatoolcalledathirdhandorhelpinghandthatcanhelpholdthingsstillforyou.Analternativeistouseabitofposterputtytoholdaniteminplacewhileyousolderit.

Whenanypaintorglueonyourboxisdry,youcanstartlayingoutyourcircuit.Beforeyoustart,youshoulddecidewhereyourArduinowillbelocatedinsideyourbox.

Here’showyoumakeyourLEDcircuit(seeFigure2-13):

1. ConnectaresistortoeachoftheLEDs.TwistthelegofaresistorwiththelonglegofanLEDsothattheydon’teasilycomeapart.Soldertheconnection.DothiswillallthreeLEDs.

2. PlacethethreeLEDsintheirholesinthebox.Bendtheshorterleg(thelegthatconnectstoground)ofthetopLEDdowntowardstheLEDbelowit.RepeatwiththemiddleLEDandbendtheshorterlegtowardsthebottomLED.

3. CutapieceofwirethatreachesfromthelegofthetopbentLEDtothemiddlebentLEDlegandthenasecondpieceofwirethatreachesfromthemiddlebentLEDlegtothebottombentLEDleg.It’sbetterforthewirestobetoolongthantooshort.Cutatleastaninchmorethanyoumeasured.Usewirestripperstostripapproximatelya½”fromeachendofthewires.

4. RemovetheLEDsfromthebox.TwistoneendoftheoneofthewireswiththeshortbentlegofthetopLED.Solderthemtogetherwithasolderingiron.

5. TwistoneendoftheotherwirewiththeshortbentlegofthemiddleLED.Solderthemtogether.

6. NowyouwillconnectthewireconnectedtotheshortlegofyourtopLEDtotheshortlegofthemiddleLED.TwisttheendofthewirehangingfromthetopLEDaroundthebentlegofthemiddleLEDandsolderthemtogether.

7. RepeatwiththewireconnectedtothemiddleLEDtoconnectittothebottomLED.8. PutyournewlyconnectLEDsintotheirholesintheboxtomakesuretheystillfit.If

theydon’t,youcancutordesolderthewiresandtryagain.9. YounowaregoingtocutthewiresthatwillreachfromtheLEDstotheArduino

Uno.YouneedtomeasureandcutthreewiresthatreachfromtheresistorsconnectedtotheLEDsandonewirethatreachesfromtheshortlegofthebottomLED.Again,cutthemaboutaninchlongerthanthemeasurementandstripa½”fromeachend.

10. SoldereachofthewirestotheirresistororLED.

Remembertoonlysolderwithanadult.Becareful;theendofthesolderingironisveryhot!

FIGURE2-13TheLEDportionofthecircuit

Nowsolderthewirestothepotentiometer(showninFigure2-14):

1. Placethepotentiometerinitshole.CutthreewiresthatreachfromthepotentiometertotheArduinoboard.

2. Stripabouthalfaninchoftheplasticfromoneendofeachofthewiresandsoldereachwiretoalegofthepotentiometer.

3. Stripabout¼”oftheplasticfromthefreeendsofeachwire.YoudothissothattheycanbeinsertedintothepinsontheArduinoboard.

FIGURE2-14Solderedpotentiometer

Atthispoint,stopandinspectyourwork.Carefullycheckthatnoneoftheexposedmetalfromthewiresorcomponentlegscantoucheachother.Iftheycan,theymightcreateaccidentalelectricalconnections.Ifthisisthecase,wrapelectricaltapearoundthemetaltopreventthathappening.

InsertingtheElectronicsWhentheglueandpaintyou’veusedtodecoratetheboxiscompletelydry,youarereadytofinishyoursignandinstallyourelectronics.

PlacetheLEDsintotheirholesinthebox.Youcanusealittleglueortapetoholdtheminplaceifyouneedto.

Thepotentiometercomeswithawasherandnutthatscrewdownonthebaseoftheshaft.Removethese,pushthepotentiometerthroughitsholeandscrewdownthewasherandnuttoholditfirmlyonthebox.Youcanmakeacontrolknobtoattachtotheendofthepotentiometerifyou’dlike.

InsertyourwiresfromyourcomponentsintotheArduinoUno.ThethreewiresconnectedtotheresistorsgotoPins5,6and7.ThewireconnectedtotheshortlegofthebottomLEDisinsertedinaGNDpin.Oneofwiresconnectedtoanoutsidelegofthepotentiometerisinsertedin5V,andtheotheroutsidelegisconnectedtoGND.TheremainingwireconnectedtothemiddlepinisinsertedinPinA0.

Younowneedtodecidehowyouwantyourprojecttobepowered.Youcan,ofcourse,leaveyourArduinoUnoconnectedtoyourcomputer,butthatcanbeinconvenient.YoucanalsostilluseyourUSBcable,butplugitintoawalladapterinsteadofyourcomputer,asshowninFigure2-15.Walladaptersoftencomewithnewmobilephones,soyoumighthaveonelyingaroundalready.AnythatletsyouconnectaUSBcableisfinetouse.

FIGURE2-15PowersupplythatyoucanusewithanArduinoboard

Congratulations!Youhavecreatedyourownstatusmessagesignthatyoucansetupandplugintodisplayamessageofyourchoice.You’vecreatedyourfirstArduinoprojectthatbreaksfreefromthecomputerandcanrunonitsown.YoursmaylookverydifferentfromtheoneinFigure2-16,andthat’sgreat!YouarewellonyourwaytobecominganArduinoexpert!

FIGURE2-16Completedstatusmessagesign

FurtherAdventureswithArduinoNowthatyoucanchangetheoutputoftheArduinoUnoaccordingtotheturnofapotentiometer,whatelsecouldyoudo?Herearesomeprojectideas:

ChangethespeedofaflashingLEDbyturningthepotentiometer.MaketheLEDsflashinasequenceandchangethespeedwiththepotentiometer.

ArduinoCommandQuickReferenceTable

Command Description

intDatatypethatcreatesanewvariablethatisaninteger(wholenumber).Seealsohttp://arduino.cc/en/Reference/Int.

Serial.begin()Startstheserialcommunicationsomessagescanbesentandreceived.Seealsohttp://arduino.cc/en/Serial/Begin.

Serial.print()Sendsamessagewithoutanewlineattheend.Seealsohttp://arduino.cc/en/Serial/Print.

Serial.println()Sendsamessagewithanewlineattheend.Seealsohttp://arduino.cc/en/Serial/Println.

analogRead()

Readsinthevoltageonthespecifiedpinandassignsitanumberfrom0(forground)to1023(for5V).Seealsohttp://arduino.cc/en/Reference/AnalogRead.

if()Usedtodeterminewhetherasectionofcodewillbeexecuted.Seealsohttp://arduino.cc/en/Reference/If.

AchievementUnlocked:Youaretakingchargeandmakingdecisions!

IntheNextAdventureYouwillstartaddingmotionandcontrollingamotorinthenextproject.

ONEWAYOFmakingyourprojectsmoredynamicisbyintroducingmovement.Whenyouaddmovementtoaprojectitcanfeelasifyou’veactuallybroughtittolife.Thisadventurewillshowyouhow,byworkingwithaservomotorandaddingswitchestoyourcircuits.

Inthisadventure,youwillstartbyfindingoutaboutthenewcomponentsyouaregoingtoworkwith,thenusethosecomponentstobuildafantasticcombinationsafe,whichonlyopenswhenyouturnallthepotentiometerstotheirsecretpositionsandpushthebutton.Ifyouknowtherightcombination,thesafeopensautomatically.Thesafeisconstructedfromcardboard,sowon’twithstandabruteforceattack,butitcanbeusedtodeterparentsfromgettinginside!

WhatYouNeedYouwillbeusinganewactuator,whichisafancywordforanobjectthattakesanelectricalsignalandthendoessomethingintherealworld.YouhavealreadyusedonetypeofactuatorinAdventures1and2:theLED.Ittakeselectricityandturnsitintolight.Inthisadventure,youuseamotorthattakeselectricityandturnsitintomotion.

Anactuatortranslatesanelectricalsignalintoareal-worldmodifiesactionsuchaslight,soundormovement.

Theoppositeofanactuatorisasensor,andyouwillbeusinganewoneofthoseaswell.Adventure2introducedthepotentiometer,whichsensesrotationandtranslatesitintoanelectricalsignal.Hereyouusepotentiometersagainandalsouseabuttontotranslateapressintoanelectricalsignal.

Asensordetectssomethingintherealworldsuchaslight,soundormovement,andtranslatesitintoanelectricalsignal.

Youneedthefollowingitems.TheelectroniccomponentsareshowninFigure3-1.

AcomputerAnArduinoUnoAUSBcableAbreadboard4jumperwiresAservomotorAtactilepushbutton110kΩresistor

FIGURE3-1TheelectroniccomponentsyouneedforthefirstpartofChapter3

UnderstandingDifferentTypesofMotorsAmotorisgeneraltermforsomethingthattakeselectricityandturnsitintomechanicalmovement,butdifferenttypesofmotorletyoucontrolthatmovementindifferentways.Whenyouthinkofamotor,thethingyouthinkofisprobablywhatiscalledaDCmotor.TheDCinDCmotorstandsfordirectcurrent.DirectcurrentisthetypeofelectricitythatyouuseinyourArduinocircuits.

Directcurrent(DC)isthetypeofelectricityusedinArduinocircuits.It’sthesamekindthatisgeneratedbyabatteryandistheoppositeofalternatingcurrent(AC),whichiswhatcomesoutofmainplugsinthewall.

ToyDCmotorsarecommoninthingslikeremotecontrolcars.WhenaDCmotorisconnectedtoDCcurrent,itspinsashaft;youcancontrolthespeedofthemotorandthedirectionitspins,butnotmuchelse.Formorecontrol,youneedsomethingthatwilldomore—eitheraservomotororasteppermotor.

Therearedifferenttypesofservomotor,butthemostcommonisknownasastandardhobbyservomotor.WithaDCmotor,theshaftspins,butyoudon’tnecessarilyknowwheretheshaftispointingwhenthemotorstops.Aservomotorknowswhichwaytheshaftispointing.Althoughyoucantellaservomotorwheretopoint,ithassomelimitations;itcanonlypointinsomedirectionsandcan’trotateafullcircle.WhereasaDCmotorcanrotatecontinuously,aservomotorcanusuallyonlyrotate180degrees.

AsteppermotorcombinesthestrengthsoftheDCandservomotorsinthatitcanrotatecontinuouslyandyoucantellitapreciselocationtorotateto.Butthatcomesataprice!Steppermotorstendtocostmorethanothertypesofmotor.There’sasolutiontothis:youcanchoosethecheaperoptionofaDCorservomotorforyourproject(seeFigure3-2)andgetroundthelimitationsbyengineeringasolutionyourself.

FIGURE3-2AservomotorandtoyDCmotor

Aservoisamotorthatcanbecontrolledtorotatetoaspecificposition.Itusuallycan’trotatemorethan180degrees.

Ifyou’dliketoreadmoreabouthowtousemotors,checkoutMakingThingsMovebyDustynRoberts(McGraw-Hill,2010).

ControllingaServowithArduinoTheArduinointegrateddevelopmentenvironment(IDE)comeswitheverythingyouneedtocontrolaservo.Itevenhasexamplesketchestogetyougoing.Inordertocontrolyourservo,youneedtoopenasketchcalledSweep.YouopenSweepbylaunchingtheArduinoIDEandclickingonFile ⇒ Examples ⇒ Servo ⇒ Sweep(Figure3-3).

FIGURE3-3OpeningtheSweepexamplesketch

Thissketchshowshowtotellaservotomove.ReadthroughthecodeintheSweepsketch.Thefirstlineofcodeafterthecommentshasn’tappearedinthecodeyouusedinAdventures1and2:#include<Servo.h>

The#includeistellingArduino’scompilerthattheSweepsketchwillbeusingsomefunctionsthataren’talwaysincludedinanArduinosketch,andthatthecompilercanfindthosefunctionsinalibrarycalledServo.ThecodetellsthecompilerthatitshouldreadthelibraryfilecalledServo.h.The<>aroundthefilenamemeansthatthefileislocatedin

thestandardlocationonthecomputerwhereallArduinolibrariesarestored.

Nowlookatthenextlineofcode:Servomyservo;

Thiscreatesanewvariablecalledmyservobutthisvariableisn’tanintegerliketheothervariablesyou’veused(suchasgreenLEDinAdventure2).Instead,itisthetypeServo(insteadofint).BecausethevariableisaServo,itholdsalltheinformationneededtocommunicatewithaservo.

ThereisjustonemorelineofcodetofinishsettinguptheservointheSweepsketch.TheArduinoUnoneedstoknowwhichpintheservowillbeconnectedto.Thisonlyneedstobedoneonce,sothatshouldhappeninthesetup()function.Afewlinesdowninthesketchyoushouldseethefollowingline:myservo.attach(9);

NowyouneedtobuildacircuittohookupyourservomotortoyourArduinoboard,whichwillenduplookinglikeFigure3-4.You’llbegladtohearthatthisneedsjustthreeconnections:5V,groundandthecontrollingpin.Unfortunatelythebadnewsisthatnotallservomotorsmakethoseconnectionsinthesameorder.Someservos(suchasthoseshowninFigures3-1and3-2)comewithalabelthatnicelyillustratestheconnections.Ifyoursdoesn’t,findoutiftheplacewhereyouboughttheservohasanyinformation.Ifthatdoesn’tprovideanyhelp,youcanjusttrywiringthecircuitindifferentcombinationsuntilitworks!

FIGURE3-4CircuittoconnectaservototheArduinoboard

Buildthecircuitfortheservo:

1. Useajumperwiretoconnectthegroundpin(maybelabelledGNDor0V)ontheservotoanyoftheGNDpinsontheArduinoUno.

2. Useasecondjumperwiretoconnectthe5Vpinontheservotothe5VpinontheArduinoUno.

3. UseathirdjumperwiretoconnecttheremainingpinontheservotoPin9ontheArduinoUno.

Afterthecircuitisbuilt,uploadtheSweepsketch(checkoutAdventure1ifyouhaven’tdonethisbefore),andwatchyourservocometolife!Itshouldstartrotatingbackandforth.Youwillhearandseeitworking.

RepeatingtheSameThingOverandOverTheArduinoboardcontrolstheservomotorthroughelectricalpulsesthattellitwheretorotate.Youdon’thavetoworryabouthowitdoesthat,asthedetailsarenicelyhandledbytheservolibrary.Allyouhavetodoistelltheservowheretogoto.Youcanchooseapositionfortheservotopointanywherebetween0and180degrees.

IntheSweepsketch,theservorotatesitsarmbackandforth.Youcouldtelltheservotodothisbycopyingandpastingmyservo.writeoverandoveragain,likethis:myservo.write(0);

myservo.write(1);

myservo.write(2);

myservo.write(3);

Thatisn’taveryefficientwaytodothings,though.Computersarereallygoodatdoingrepetitivetasks,sothere’sabetterwaytomaketheservorotatebackandforth.Ifyou’vereadthecodeintheSweepsketchtoseehowit’sdonethere,youmighthavenoticedaprogrammingtoolcalledaforloop.

Aforloopisaprogrammingdevicethatrepeatsablockofcodeforapredeterminednumberoftimes.

TheSweepsketchhastwoforloops.Here’sthefirstone:for(pos=0;pos<180;pos+=1)

{

myservo.write(pos);

delay(15);

}

Tosetupaforloop,youneedtoprovidethreepiecesofinformation:

1. Firstofall,youneedtostatewhatthestartingconditionis.InthistheSweepsketchit’spos=0.

2. Next,youneedtosaywhatneedstohappenfortheforlooptocontinue.Here,poshastostaybelow180(expressedincodeaspos<180).Whenposisequaltoorlargerthan180,theloopstopsandthecodeinbetweenthe{and}isnolongerexecuted.

3. Finally,youneedtosaywhatchangeseachtimetheloopisexecuted.IntheSweepsketch,1isaddedtoposeachtimethecodeinbetween{and}isexecuted.Thisiswrittenaspos+=1,forshort,butyoucanwriteitinanumberofways;youcouldwriteitaspos=pos+1orpos++.

Thecomputerdoesn’tnoticeindentsorspacesbetweenpiecesofcode.Sometimescodehasspacesaddedtomakeiteasiertoread.ThefollowingtwolinesofcodelookthesametotheArduino.

for(pos=0;pos<180;pos+=1)

for(pos=0;pos<180;pos+=1)

It’seasiertoseethethreepartsoftheforloopwhentherearespacesincluded.

Phew!It’sprobablytimeforarecap.Inthisexample,intheforloop,posstartsat0.Because0islessthan180,thecodeinthe{}isexecuted.Theservoissetto0andthenpausesfor15milliseconds(byusingthedelay()function).1isaddedtopos,soitnowequals1.Because1islessthan180,theservoissetto1andthenpausesfor15milliseconds.Thiskeepshappeninguntilposis179.Theservoissetto179and1isaddedtoposmakingit180.posisnolongerlessthan180,sothecodeinthe{}isskippedandtheArduinogoesontothenextlineofcodeaftertheforloop.

CHALLENGE

WhatishappeninginthesecondforloopintheSweepsketch?Thisiswhatitlookslike:

for(pos=180;pos>=1;pos-=1)

{

myservo.write(pos);

delay(15);

}

Changetheforloopsothattheservoonlyrotatesfrom0to90.

DigitalInputwithaPushButtonYoumightthinkthesimpleswitchwouldbequiteastraightforwardelectricalcomponent,butinfactswitchesaredeceptivelycomplicated.Theycomeinmanyshapesandsizes.Youhavemanyoftheminyourhousetoturnonandoffyourlights.Alltheydoiscompleteorinterruptacircuit.Sometimestheychangewherethecurrentflowsinacircuit,butthetypeofswitchthatturnsyourlightsonandoffismadefromtwopiecesofmetalthateithertouchordon’ttouch,dependingonthepositionoftheswitch.

Aswitchisacomponentthateitherdisruptsorredirectstheflowofcurrentinacircuit.

Thereisanothertypeofswitch,calledatactilepushbutton.Italsohastwopiecesofmetalinsideofit,butinthiscasetheyonlytouchwhenthebuttonisactuallybeingpressed.Atactilepushbuttonhasfourlegs,butit’sbettertothinkofthemastwopairsoflegsbecausethetwolegsineachpairarealwayselectricallyconnected—evenwhentheswitchisnotbeingpressed.Whenthebuttonispressed,allfourlegsareelectricallyconnected.SeeFigure3-5foranillustrationofhowatactilepushbuttonworks.

Atactilepushbuttonisatypeofswitch.Apush-to-breakpushbuttoninterruptstheflowofcurrentinacircuitwhenitispressed.Apush-to-makepushbuttondoestheoppositebyinterruptingcurrentonlywhenitisnotpressed.

FIGURE3-5Howatactilepushbuttonworks

Nowyou’regoingtobuildthecircuit,includingapushbutton,asshowninFigure3-6.

1. Insertthepushbuttonintofourrowsinthecentreofyourbreadboard.Thepush

buttonfitsoverthegapinthemiddle,sotwolegsareinsertedintworowsonthetophalfoftheboardandtheothertwolegsareintworowsonthebottomhalfoftheboard.

2. Useajumperwiretoconnecttherowwherethebottom-rightlegofthepushbuttonisinsertedtooneofthelongrowsalongthebottomofthebreadboard.Ifyourbreadboardislabelledwithablackorbluelineora-,connectittothatrow.Ifyourbreadboardisn’tlabelled,connectittoeitherrow.

3. UseanotherjumperwiretoconnectthelongrowconnectedtothepushbuttontooneoftheGNDpinsontheArduinoUno.

4. UseajumperwiretoconnectPin2ontheArduinoUnototherowconnectedtothetop-leftlegofthepushbutton.

FIGURE3-6Circuitwithatactilepushbutton

Nowyou’vebuiltyourcircuit,opentheexamplesketchatFile ⇒ Examples ⇒ 01.Basics ⇒ DigitalReadSerial.UploadthesketchandopentheSerialMonitorbyclickingthebuttonintheArduinoIDEorgoingtoTools ⇒ SerialMonitor.

Ready?Timetopressandreleasethebutton.WhathappensintheSerialMonitor?Whenyourfingerispressingthebutton,youshouldseea0printed;whenthebuttonisnotbeingpressed,youshouldseeamixtureof0sand1s.Thesequenceof0sand1sisrandom,soyoumightseemostly0sormostly1sratherthananevenmixtureofthetwo.Thisiswhat’scalledafloatinginput.Whenthebuttonisn’tbeingpressed,thepinisn’tconnectedtoavoltagesourcesuchasgroundor5V—it’sfloating.TheArduinoUnoisreadinginrandomvaluesfromthatpin.

Afloatinginputisapinthatisnotconnectedtoanything.Thepinreadsinrandomvaluesifitisnotconnectedtoavoltagesource,suchasground,5Vorasensor.

It’snotagoodthingtohavefloatingvalues.ThemainreasonisthatwhentheArduino

“readsin”adigitalsignalfromapin,itreadsina0whenthepinisconnectedtogroundandreadsina1whenit’sconnectedto5V.Ifthepinisn’tconnectedtoeithergroundor5Vandisrandomlyreadingin0and1,thenit’simpossibleforyourcodetomakegooddecisionsbasedontheinputfromthatpin.Ifyouwanttostartamotormovingonlywhenabuttonispressed,connectingthatpintoground,thenyoucan’thavethepinreadingin0whenthebuttonisn’tpressed.

Thewayaroundthisproblemistouseakindofresistorcalledapull-upresistor.Apull-upresistorgivesadefaultvalueof5Vtoapinbyalwaysconnectingthatpinto5V.Thepinisalsoconnectedtothepushbutton,andthepushbuttonisconnectedtoground.Theresistorusuallyhasquiteahighvalue,suchas10kΩ.Thereisnoresistancebetweengroundandthepinwhenthebuttonispressed,sothepinconnectstogroundinsteadof5Vthroughthepull-upresistor.Electricityalwayschoosesthepathwiththeleastresistance,and,inthiscase,thatisthepathbetweengroundandthepin.

Apull-upresistorisaresistorthatisconnectedtothehighvoltageinacircuit,whichsetsthedefaultstateofthepinonthatcircuittoHIGH.Theresistorisusually10kΩ.

Likemostthingswithelectronics,theeffectofapull-upresistorismucheasiertounderstandwhenyouactuallybuildacircuitandseewhathappensforyourself.That’swhatyou’regoingtodonow.ChangethecircuitonyourbreadboardtotheoneshowninFigure3-7.

1. Startwiththecircuityoujustbuiltwiththepushbuttoninthecentreofthebreadboard.

2. Useajumperwiretoconnectfromthe5VpinontheArduinoUnototheotherlongrowalongthebottomofthebreadboard(theonethatisn’tconnectedtoground).

3. Placeonelegofthe10kΩresistorinthesameshortrowasthelower-leftlegofthepushbutton.Inserttheotherlegoftheresistorintothelongrownowconnectedto5V.

FIGURE3-7Circuitwithapull-upresistor

Youdon’tneedtochangeanythinginyourArduinocode,andyoucanjustleavetheSerialMonitoropen.Now,whathappenswhenyoupressandreleasethebutton?Itshouldnowonlyshow0whenthebuttonispressedand1whenitisreleased.

TheArduinoboardhaspull-upresistorsbuiltintoitalready,soyoucanusetheseinsteadofbuildingapull-upresistorintoyourcircuitonthebreadboard.Todothis,youfirstindicatethatyouwanttouseoneofthebuilt-inpull-upresistorswhenyousetupthepinMode()insetup(),bytypinginthefollowingcode:pinMode(pushButton,INPUT_PULLUP);

Next,changetheDigitalReadSerialsketchsothatthesecondargumentofpinModeisINPUT_PULLUPinsteadofINPUT.Yoursetup()shouldlooklike:voidsetup(){

//initializeserialcommunicationat9600bitspersecond:

Serial.begin(9600);

//makethepushbutton’spinaninput:

pinMode(pushButton,INPUT_PULLUP);

}

Finally,uploadthesketchagainandchangeyourcircuitonyourbreadboardtotheoneinFigure3-8byremovingthe10kΩresistorandjumperwireconnecting5Vandoneofthelongrows.Yourbuttonshouldactthesamewayasitdidwhenyouhadthepull-upresistoronthebreadboard.

FIGURE3-8Circuitwithapushbuttonandinternalpull-upresistorontheArduinoboard

BuildingaCombinationSafeWelldone!Youhavebuiltupquiteanarsenalofsensorsandactuators.Nowyoucanstartputtingthemtogethertomakesomethingverycoolandveryuseful:acombinationsafethatopensandclosesautomatically(seeFigure3-9).Toopenthesafe,youdialinacombinationandpushabutton.Theboxwillonlyopenifthecombinationiscorrect,anditwillstayopenuntilyoureleasethebutton.Itcanbeagreatplacetokeepasecretcandystashorkeepyourfavouritepensandpencilsfrombeing“borrowed”withoutyourpermission.

FIGURE3-9Combinationsafe

WhatYouNeedYouneedtheitemsinthefollowinglisttobuildyoursafe.Itincludesthecomponentsyouneedtoprototypeyourcircuitonabreadboardandthecomponentsyouuseinyoursafe.Figure3-10showstheelectroniccomponentsyouneed.

FIGURE3-10Theelectroniccomponentsyouneedtobuildyourcombinationsafe

Youuseadifferentbuttoninyoursafethanonyourbreadboard.Youuseapanelmountpushbuttoninsteadofatactilepushbutton.Youstilluseatactilepushbuttontotestyourcircuitonabreadboard,butthepanelmountbuttonisbiggerandeasiertomountonacardboardbox.Youfindouthowtoconnectwirestothepanelmountbuttonlaterinthischapter.

Apanelmountpushbuttonisapushbuttonthatisdesignedtobemountedinsideacase.Itcomeswithanutandwashertosecureittoapanel.

Havethefollowingsuppliesonhandbeforeyoustarttheproject:

AcomputerAnArduinoUnoAUSBcableAbreadboard16jumperwiresAtactilepushbutton(push-to-make)Apanelmountpushbutton(push-to-make)

Aservomotor310kΩpotentiometersSomesolderAsolderingironSomewireApapercliporbambooskewerAsmallboxwithalidtobeyoursafeAhotgluegunScissorsorautilityknife

Yourboxcanbeanysize,butaboxapproximatelythesizeofashoeboxworkswell.Itworksbestifthelidisalreadyattachedtothebaseofthebox,butthelidisn’tattached,Iexplainhowyoucanattachityourself.

Youcanalsouseanythingyouwouldliketodecorateyourbox,suchaspaintorpaper.

Visitthecompanionwebsitetoseeavideoshowinghowthebuildingthesafe(www.wiley.com/go/adventuresinarduino).

UnderstandingtheCircuitThecircuitforthesafehasthreecomponentsaservo,threepotentiometersandapushbutton.Thethreepotentiometersarereadintothreeanalogpinsandthepushbuttonisreadintoadigitalpin.Theservomotoriscontrolledfromanotherdigitalpin.

Figure3-11showstheschematicforthesafe.Lookscomplicated,doesn’tit?Don’tworry;youwillbuilditstepbystep.Beforeyousolderthecircuitforyoursafe,you’regoingtomakeaprototypeofitonyourbreadboard.

FIGURE3-11Circuitschematicforthecombinationsafe

Incircuitschematics,lineshowingconnectionsoftencrossovereachother.Inordertomakeitlessconfusing,twolinesareelectricallyconnectedtoeachotheronlywhenthereisacircleovertheirintersection.Otherwise,theyaretwoindependentwiresthatdon’telectricallymakecontact.

PrototypingonaBreadboardYoushouldalwaysprototypeacircuitonabreadboardbeforebuildingyourfinalproject.It’smucheasiertofixanyerrorsbeforeyouhavestartedcuttingwireandsolderingconnectionstogether!BuildthecircuitonabreadboardasshowninFigure3-12.

1. Startbyplacingthetactilepushbuttonontherightofthebreadboard.Itshouldfitoverthegapinthemiddleofthebreadboard,andeachofthefourlegsshouldbepushedintothenearestrows.

2. Placethreepotentiometersevenlyacrosstherestofthebreadboard.Eachlegofthepotentiometersshouldbeinitsownrowonthebreadboard.

3. Useajumperwiretoconnectthe5VpintooneofthelongrowsalongthebottomofthebreadboardandasecondjumperwiretoconnectaGNDpintotheotherlongrow.Ifyourbreadboardislabelled(notallare),thenconnect5Vtotherowwitharedlineor+,andconnectGNDtotherowwithablueorblacklineor-.

4. ConnecttheleftlegofeachpotentiometertothelongrowconnectedtoGNDusingthreejumperwires.

5. Connecttherightlegofeachpotentiometertothelongrowconnectedto5Vusingthreejumperwires.

6. Connectthelower-rightlegofthepushbuttontoGND.7. UsethreejumperwirestoconnectthemiddlepinofeachpotentiometertoPinsA0,

A1andA2.8. Useajumperwiretoconnectthetop-leftlegofthepushbuttontoPin7.9. Makethethreeconnectionsfortheservo.Connectthegroundpinoftheservotothe

longrowonthebreadboardconnectedtoGND,connectthe5Vpinoftheservotothelongrowconnectedto5VandconnecttheremainingpinontheservotoPin9ontheArduinoUno.

FIGURE3-12Circuitforthecombinationsafe

WritingtheCodeJustlikethecircuit,thesketchforthesafelookscomplicatedatfirst.Butafteryoubuilditup,step-by-step,youwillseethatsketchisjustthecombinationofsmallersectionsofcode.Thecodedetectswhetherthebuttonisbeingpressed.Ifitis,theArduinoUnocheckswhetherthethreepotentiometersareturnedtothecorrectvaluestoopenthebox.Iftheyare,thentheboxopens;iftheyaren’t,thennothinghappens.

StartbylaunchingtheArduinoIDE.Startanewsketchwithanemptysetup()andloop():voidsetup(){

}

voidloop(){

}

Attheverytopofyoursketchbeforesetup(),addthefollowinglines:#include<Servo.h>

//Pins

intpotPin1=A0;

intpotPin2=A1;

intpotPin3=A2;

intbuttonPin=7;

intservoPin=9;

//othervariables

intopen1=0;

intopen2=1023;

intopen3=0;

intrange=10;

intboxOpen=0;

Servoservo;

Thefirstlineimportsthelibrarytocontroltheservoandtherestofthelinesarevariables.Thefirstgroup(under//Pins)arethevariablestokeeptrackofwhichpinsareconnectedtothesensorsandactuator.

Thenextfivevariablesareforcontrollingthebox.Thevariablesopen1,open2andopen3arethevaluesthatthepotentiometersneedtobeturnedtoinordertoopenthebox.Becauseitcanbedifficulttoturnthepotentiometertoaprecisenumber(especiallywhenyouaren’tusingSerialMonitortoseetheexactvaluesfromthepotentiometers),therangevariableisusedtodeterminehowcloseyouhavetobetotherightnumber.Forexample,anyvaluefromopen2-rangethroughtoopen2+rangeregistersthesecondpotentiometerasbeinginthecorrectposition.Thelargerthenumberstoredinrange,theeasieritistoopenthebox.

TheboxOpenvariableisusedtokeeptrackofwhethertheboxisopenedorclosed.Theboxstartsclosed,sothevariableissetto0.Whenitisopened,itissetto1andthenchangedbackto0whentheboxisclosed.Theloop()functionholdsthecodethat

controlsboxOpen.

Thelastvariableisafamiliarone:servo.Itisthevariablethatcommunicateswiththeservo.

Thenextstepistoaddthecodetothesetup()://setbuttonpintobeaninputwith

//withpull-upresistor

pinMode(buttonPin,INPUT_PULLUP);

//attachservotopin

servo.attach(servoPin);//attachestheservoonpin9

//totheservoobject

servo.write(90);//startwiththeboxclosed

Serial.begin(9600);//startserialcommunication

Thefirstlineofsetup()setsthepinMode()forthepushbuttonandturnsontheinternalpull-upresistor.Therestofthefunctionattachestheservotoitspin,makessuretheservohasclosedtheboxandthenstartsserialcommunication.

Finishyoursketchbyaddingthefollowingtotheloop()://checkifbuttonispressed

intbuttonValue=digitalRead(buttonPin);

//ifbuttonispressedandboxisclosed

if(buttonValue==0&&boxOpen==0){

//buttonispressed

intpotValue1=analogRead(potPin1);

intpotValue2=analogRead(potPin2);

intpotValue3=analogRead(potPin3);

Serial.print("pot1:");

Serial.print(potValue1);

Serial.print("pot2:");

Serial.print(potValue2);

Serial.print("pot3:");

Serial.println(potValue3);

//ifallvaluesarewithincorrectrange

if(potValue1<(open1+range)&&

potValue1>(open1-range)&&

potValue2<(open2+range)&&

potValue2>(open2-range)&&

potValue3<(open3+range)&&

potValue3>(open3-range)

){

//openthebox

Serial.println("opening");

for(intpos=90;pos>0;pos-=1)

{

servo.write(pos);

delay(15);

}

boxOpen=1;

}

}

//ifbuttonispressedandboxisopen

if(buttonValue==1&&boxOpen==1){

Serial.println("closing");

//closethebox

for(intpos=0;pos<90;pos+=1)

{

servo.write(pos);

delay(15);

}

boxOpen=0;

}

Younowhaveacompletesketchandyouarereadytocheckwhetheryourcircuitisworkingcorrectly.UploadyoursketchtotheArduinoUnoandopentheSerialMonitor.Turnthepotentiometersuntiltheymatchthevaluesstoredinopen1,open2andopen3,andthenpushandholdthebutton.Theservoshouldrotateandstop.Releasethebuttonandtheservoshouldreturntoitsstartingposition.

TheDiggingintotheCodesectiongoesthroughtheloopinmoredetailtoexplainhowyoursafefunctions.Here’sthefullsketch:#include<Servo.h>

//Pins

intpotPin1=A0;

intpotPin2=A1;

intpotPin3=A2;

intbuttonPin=7;

intservoPin=9;

//othervariables

intopen1=0;

intopen2=1023;

intopen3=0;

intrange=10;

intboxOpen=0;

Servoservo;

voidsetup(){

//setbuttonpintobeaninputwith

//withpull-upresistor

pinMode(buttonPin,INPUT_PULLUP);

//attachservotopin

servo.attach(servoPin);//attachestheservoonpin9totheservo

object

servo.write(90);//startwiththeboxclosed

Serial.begin(9600);//startserialcommunication

}

voidloop(){

//checkifbuttonispressed

intbuttonValue=digitalRead(buttonPin);

//ifbuttonispressedandboxisclosed

if(buttonValue==0&&boxOpen==0){

//buttonispressed

intpotValue1=analogRead(potPin1);

intpotValue2=analogRead(potPin2);

intpotValue3=analogRead(potPin3);

Serial.print("pot1:");

Serial.print(potValue1);

Serial.print("pot2:");

Serial.print(potValue2);

Serial.print("pot3:");

Serial.println(potValue3);

//ifallvaluesarewithincorrectrange

if(potValue1<(open1+range)&&

potValue1>(open1-range)&&

potValue2<(open2+range)&&

potValue2>(open2-range)&&

potValue3<(open3+range)&&

potValue3>(open3-range)

){

//openthebox

Serial.println("opening");

for(intpos=90;pos>0;pos-=1)

{

servo.write(pos);

delay(15);

}

boxOpen=1;

}

}

//ifbuttonispressedandboxisopen

if(buttonValue==1&&boxOpen==1){

Serial.println("closing");

//closethebox

for(intpos=0;pos<90;pos+=1)

{

servo.write(pos);

delay(15);

}

boxOpen=0;

}

}

DIGGINGINTOTHECODE

Let’slookattheloop()ofthecodeyou’vejustinputinalittlemoredetail.

ThevalueofthebuttonPinisreadin.Ifthevalueis0andtheboxisclosed,thenthevaluesofeachofthepotentiometersareread:

//checkifbuttonispressed

intbuttonValue=digitalRead(buttonPin);

//ifbuttonispressedandboxisclosed

if(buttonValue==0&&boxOpen==0){

//buttonispressed

intpotValue1=analogRead(potPin1);

intpotValue2=analogRead(potPin2);

intpotValue3=analogRead(potPin3);

ThevalueofeachpotentiometerisprintedtotheSerialMonitortohelpwithanydebugging:

Serial.print("pot1:");

Serial.print(potValue1);

Serial.print("pot2:");

Serial.print(potValue2);

Serial.print("pot3:");

Serial.println(potValue3);

Ifeachpotentiometeriswithinrangeofthecorrectvalue:

//ifallvaluesarewithincorrectrange

if(potValue1<(open1+range)&&

potValue1>(open1-range)&&

potValue2<(open2+range)&&

potValue2>(open2-range)&&

potValue3<(open3+range)&&

potValue3>(open3-range)

){

thentheboxisopenedbyusingaforlooptorotatetothe0position.YouknowiftheboxisclosedifboxOpenis0.Aftertheboxisopen,boxOpengetssetto1sothatyouhaveconfirmationthattheboxisopen.

//openthebox

Serial.println("opening");

for(intpos=90;pos>0;pos-=1)

{

servo.write(pos);

delay(15);

}

boxOpen=1;

}

}

IfthevalueofthebuttonPinis1andtheboxisopen,theboxisclosedbyusingaforlooptorotatetheservotoposition90.TheboxOpenvariableisthensetto0.

//ifbuttonispressedandboxisopen

if(buttonValue==1&&boxOpen==1){

Serial.println("closing");

//closethebox

for(intpos=0;pos<90;pos+=1)

{

servo.write(pos);

delay(15);

}

boxOpen=0;

}

Ifthebuttonispressedwhiletheboxisalreadyopen,orthebuttonisreleasedwhiletheboxisalreadyclosed,thennothingisdoneandtheloop()isrepeated.

CHALLENGESetyoursecretcombinationtoopenthesafeusingtheopen1,open2andopen3variables.Adjusthoweasyitistodialinthenumbersusingrange.

MakingtheSafeAtlast,you’rereadytomakeyoursafe!ThisisverysimilarinconstructiontothestatusmessagesigninAdventure2.You’regoingtouseabox(suchasashoebox)tohousetheelectronics.

1. Attachthelidtothebox.Whenyouattachthelid,makesureyouattachitalongonesidesothatithingesopenandshut.Thatway,theservomotorcandramaticallypushtheliduptoopentheboxwithoutthelidfallingoff.Onewayofdoingthisistomakeapaperhingewithastripofpaperandglue,asshowninFigure3-13.

2. Next,youneedtodecidewhereyouwanttoputyourpotentiometersandbutton.Thisisentirelyuptoyou,althoughyouprobablywantthemtobeonthefrontoftheboxforeasyaccess.Cutholessothattheshaftsofthepotentiometersandbuttonfitsnugly.CutaholethatcanpasstheUSBcableintotheboxtopowertheArduinoUno.

3. Servomotorscomewithaselectionofdifferentarms.Thesepopontotheendoftherotatingshaftoftheservomotor.Youwanttousetheonethatisasinglearmextendingfromtheshaft.(Don’tusethecrossarm.)

Thearmisn’tverylong,soyoucanextenditbyattachinganotherobjecttoit.Youcanuseanythingyoulike,butabambooskewerorpaperclipworkswell.Gluetheobjecttotheservoarmandmakesureit’sfirmlyattached(seeFigure3-14).

4. UploadthesketchforthesafeontotheArduinoUnoandsetuptheprototypecircuitonthebreadboardifyouhaven’tdonesoalready.

5. Removeanyarmattachmentsfromtheservo.IfthecodeisrunningontheArduinoboardandyouaren’tpressingthebutton,theservoshouldberotatedtothe90position.Nowattachtheservoarmsothatitisat90degrees—positionitsothatitwon’tpushthelidoftheboxup.Whenyoudialthecorrectcombinationandpressthebutton,theservoarmshouldrotatetopointstraightup.

6. Theextendedarmoftheservopushesuptheclosedlid,buthowdoesitcloseitagainafterit’sopen?CreateapaperloopthatisattachedtotheundersideofthelidasinFigure3-15.Theextendedarmoftheservogoesinthisloopandusesittopullthelidclosed.

FIGURE3-13Ifthelidisnotalreadyattachedtoyourbox,addapaperhinge.

FIGURE3-14Extendtheservo’sarmbyattachinganobjectlikeapapercliporbambooskewer.

FIGURE3-15Paperloopsotheservocanclosethesafe

SolderingtheWiresUsethefollowingstepstosolderthewires:

1. Placethepotentiometersintheirholesinthebox.MeasureandcutfourpiecesofwirethatreachfromthepotentiometerfarthestfromtheArduinoUnotothenextnearestpotentiometer.Cutthemaboutaninchlongerthanyouneed.Stripabout½”fromtheendofeachwire.RepeatandcutawirethatreachesfromthemiddlepotentiometertotheoneclosesttotheArduinoUno(seeFigure3-16).Thesewiresconnecttheoutsidelegsofthepotentiometerstoeachother.

2. CuttwopiecesofwirethatreachfromtheoutsidelegsofthepotentiometerclosesttotheArduinoUnotothe5VandGNDpinsontheboard.Cutthemaboutaninchlongerthanyouneedandusewirestripperstostripabout½”fromeachendofthewires.

3. Cutapieceofwirethatreachesfromtheclosestpotentiometertotheconnectorontheservo.Cutitaboutaninchlongerthanyouneedandusewirestripperstostripabout½”fromeachendofthewires.

Remembertosolderonlywithadultsupervision.Visitthecompanionsiteforvideosabouthowtosolder(www.wiley.com/go/adventuresinarduino).

4. SoldertheoutsidelegsofthetwopotentiometersfarthestfromtheArduinoUnotoeachotherusingthewiresasshowninFigure3-16.

5. SolderthewiresforthepotentiometerclosesttotheArduinoUno.Oneoftheoutsidelegswillhavetwowiressolderedtoit—onefromthemiddlepotentiometerandawirethatconnectstotheArduinoUno.Theotheroutsidelegsofthepotentiometerwillhavethreewiressolderedtoit—theremainingwirefromthemiddlepotentiometer,awirethatconnectstotheArduinoUnoandawirethatconnectstotheservo.

6. MeasureandcutthreepiecesofwirethatreachfromeachofthepotentiometerstoPinsA0,A1andA2ontheArduinoUno.Cutthemeachaboutaninchlongerthanyouneedandstripabout½”fromtheendofeachwire.

7. Solderoneendofeachwirethemiddlelegofeachpotentiometer.8. Placethepanelmountpushbuttoninitshole.Measureandcuttwopiecesofwire

thatreachfromthepushbuttontoPin7andaGNDpinontheArduinoUno.Cutthewireaboutaninchlongerthanyouneedandstripabout½”fromtheendofeachwire.

9. Solderonewiretoonelegofthepushbuttonandtheotherwiretotheotherleg.

FIGURE3-16Solderedcomponents

Tosummarise:

YouwillhavethreewirescomingfromthemiddlelegofeachpotentiometerthatwilleventuallyconnecttotheArduinoUno.ThepotentiometerfarthestfromtheArduinoUnowillhaveonewireconnectedtoeachoutsidelegthatconnectsthemtooutsidelegsofthenextpotentiometer.Themiddlepotentiometerwillhavetwowiresconnectedtoeachoutsideleg:awireconnectingthatlegtothefirstpotentiometerandawireconnectingittothelastpotentiometer.Thelastpotentiometerwillhavetwowiresconnectedtooneoutsidelegandthreewiresconnectedtotheotheroutsideleg.ThelegwithtwowireswillbeconnectedtothemiddlepotentiometerandtheremainingwirewilleventuallyconnecttotheArduinoUno.Thelegwiththreewiresisconnectedtothemiddlepotentiometer,toawirethatwillconnecttotheservoandtoawirethatwillconnecttotheArduinoUno.Thepushbuttonhasonewireconnectedtoeachleg.ThesewilleventuallyconnecttotheArduinoUno.

Everyboxwillbealittledifferent.Thesizeswillbedifferent,andlidswillbelooserortighter.Youmayhavetobecreativetosolveengineeringproblemssothatyourboxopensandcloses.Forexample,youmightneedtoattachapaperloopontheundersideofthelidsothattheservoarmcatchesitandpullstheliddown(refertoFigure3-15).

Whynottrymakingyourownpaperbox?Findanorigamibookinyourlibraryorlookonlineforaboxandlidpattern.

InsertingtheElectronicsThepotentiometersandpushbuttoncomewithnutsandwashersthatthreadontothebaseoftheshafts.Removethenutsandwashersandthenstickthestemsofthepotentiometersandpushbuttonthroughtheholesyou’vemadeinyourbox.Screwthewashersandnutsbackontosecurethecomponentstothecardboard.Addsomeglueiftheystillwigglearoundmorethanyou’dlike.

Insidethebox,buildyourcircuitbyconnectingthewirestotheirrespectivepinsontheArduinoUno.Oneofthewiressolderedtoanoutsidepinofapotentiometerwiththreewiressolderedtoitshouldbeinsertedin5V;theotheronefromthelegwithtwowiressolderedtoitshouldbeinsertedinaGNDpin.ConnectthethreewiresfromthethreepotentiometerstoPinsA0,A1andA2.ConnectonewirefromthepushbuttontoaGNDpinandtheotherwiretoPin7.Connectthelastwirefromthepotentiometerlegwiththreewiressolderedtoittothe5Vconnectionontheservo.UsetwojumperwirestoconnecttheservotoGNDandin9.

Goaheadandtestitout!Younowhaveaboxwithasecretcodethatautomaticallyopens.Figure3-17showsthecompletedwiring.

FIGURE3-17Completedcombinationsafe

FurtherAdventureswithArduinoNowthatyouhavesomeservoexperienceunderyourbelt,checkouttheseprojects:

http://playground.arduino.cc/ComponentLib/Servo

http://arduino.cc/en/pmwiki.php?n=Tutorial/Knob

WorkingwithservosandArduinoisjustthebeginningofwhatyoucandointhefieldofrobotics.Checkouttheseamazingrobots—manybuiltusingArduino!

http://artbots.org/2011/participants/

http://makezine.com/projects/building-a-simple-arduino-robot/

http://www.makershed.com/collections/robotics

ArduinoCommandQuickReferenceTable

Command Description

#include Commandtoimportalibrary.Seealsohttp://arduino.cc/en/Reference/Include.

Servo.h Librarytocontrolaservo.Seealsohttp://arduino.cc/en/reference/servo.

Servo Objectforcontrollingaservo.Seealsohttp://arduino.cc/en/reference/servo.

Servo.attach() AttachaServovariabletothespecifiedpin.Seealsohttp://arduino.cc/en/Reference/ServoAttach.

Servo.write()Writeavaluetotheservototellitwhatpositiontomoveto.Seealsohttp://arduino.cc/en/Reference/ServoWrite.

for Loopsoverasectionofcodeacertainnumberoftimes.Seealsohttp://arduino.cc/en/Reference/For.

AchievementUnlocked:Youaresuccessfullycombiningcircuitsandcode!

IntheNextAdventure…AfewLEDsaregood,butlotsofLEDsareevenbetter!InthenextadventureyoufindouthowtocontrollargebatchesofLEDswithsmallcircuitchipscalledshiftregisters.

YOUAREWELLonyourwaytobecominganArduinoexpert.You’vetackledallsortsofthings,frommotorstopotentiometers.You’veevenhandledthreepotentiometersatthesametime.Butwhataboutworkingwithmorethanthreeofthesamething?OneLEDisgood,threeLEDsarebetter—buthowabout24LEDs?

AsanexperiencedArduinoengineer,youmighttakealookatyourArduinoboardandquestionmycountingabilities.Therearen’t24outputpinsforLEDsonyourboard?You’reright!Butyoucanharnessthepowerofspecialchipscalledshiftregisterstoextendthenumberofoutputs,andthat’swhatyou’regoingtodointhisadventure.

Codecanstartgettingalittlemessywhenyou’reworkingwithsomanyoutputs,soI’llshowyousomewaystokeepyourcodetidyandeasiertounderstand.

Whenyouputitalltogetherattheendoftheadventure,youwillmakeacarnival-stylelight-upsignthatspellsoutyourname(oranyotherwordyouchoose).

WhatYouNeedForthestartofthisadventure,youneedabreadboard,LEDsandresistors.You’regoingtobeexploringdifferentwaystolightupacollectionofLEDsincode.Youthenfindoutwhatashiftregisterisandhowtouseit.Youneedthefollowingitems;theelectroniccomponentsareshowninFigure4-1:

AcomputerAnArduinoUnoAUSBcable1largebreadboardor2smallones38jumperwires16LEDs16220Ωresistors274HC595shiftregisterintegratedcircuits(ICs)

FIGURE4-1Whatyouneedforthefirstpartofthisadventure

Integratedcircuit(IC)namescanbequitelongandseemcomplicated,buttheyarejustholdingalotoflittlepiecesofinformation.Forthisadventure,you’reusingthe74HC595shiftregister,andthat’sthesetofnumbersandlettersthatyouneedtolookforwhenyoubuythepart.Ifyougetachipthathastwolettersinthepartnumberbefore74HC595,it’sokay.Theseareacodeforthecompanythatmakesthechip.Chipslikeshiftregistersaremadebylotsofdifferentcompanies,soyoudon’tneedtoworryifthechipyouarethinkingaboutbuyinghasthesetwoextraletters.Aslongasthechipsyoubuyhasthenextsetofnumbersandletters(74HC595),whatyouhaveisgood.Theremaybeanadditionallastlettertellsyouwhatshapeorpackagethechipis.Forbreadboardcircuits,youwantittobeNforaDIP(apackagewithtworowsoflegsthatfitsintoabreadboard).Thesection“GettingMoreOutputswithShiftRegisters”explainsmoreaboutwhatthatmeans.

OrganisingYourCodeCodeissimplywritteninstructionsthatacomputercanunderstand.Often,youhavetorepeatthoseinstructions.Insuchcases,youcansavetimebycopyingandpastingthesamepieceofcodemultipletimestogetthecomputertorepeatthesamesetofinstructions.Butwhatifyoumakeasmalltypo?Maybeyoumissasemicolon?Thetiniestmistakecanleadtoyourprogramnotworkingproperly.Itcanbehardtofigureoutwhyitworksthefirsttwotimesandthenfailsthethirdtime.Longsectionsofrepeatedcodecanalsomakeitmoredifficulttofollowwhatishappeninginyoursketch.Yourcodebecomeslessreadable.

Programmersliketojokethattheyarelazyanddon’twanttodomoreworkthannecessary!Socomputerscientistswhowriteprogramminglanguagesspendalotoftimedesigningthewayinstructionsarewrittenout,tohelpminimisetheriskofmakingsimplemistakeswhendoingthingslikecopyingandpastingcode.Thefollowingsectionsintroduceyoutosomeofthetechniquesyoucanusetosimplifyyourcode.

UsingFunctionsOneeasywaytorepeatcodeistoputthelinesofcodeyouwanttoberepeatedintosomethingcalledafunction.It’slikegivinganametoasetofinstructions.Youthenonlyneedtowriteoutthenameofthegroupofinstructionseachtimeyouwantthemtohappen,insteadwritingalloftheinstructionsindividually.

Ifyou’veworkedthroughtheearlieradventures,youhavealreadybeenusingfunctionswrittenbysomeoneelse.Forexample,digitalWrite()isafunctionthatcontrolsaDigitalPinontheArduinoUno.Thefunctionhandlesallthedetailsofturningonandoffthepin;youjusthavetocallthefunction.Nowyougettostartwritingyourownfunctions.

You’regoingtoaddfunctionstotheBlinksketchinthisadventure.YoumightrecallthatI’vetalkedaboutfunctionsbefore—inparticular,thesetup()andloop()functions.Thesearefunctionsjustliketheonesyou’regoingtouseintheBlinksketch,butyoudon’tgettogivethemyourownnames;theyhavetobecalledsetup()andloop().WhentheArduinofirststartsup,itlooksforafunctioncalledsetup()andexecutesthelinesofcodeinit.Itthenlooksforafunctioncalledloop()andrepeatedlydoeswhateverlinesofcodeareinthatfunction.

It’salwayseasiertounderstandanewconceptwhenyougettotryitoutyourself,sotakealookattheBlinksketchyoufirstworkedwithinChapter1.OpenupthesketchbygoingtoFile ⇒ Examples ⇒ 1.Basics ⇒ Blink.ThefirstthingyouneedtodoissaveacopyoftheBlinksketch.You’resavingacopyratherthanusingtheoriginalexamplebecauseyou’regoingtomakesomechangestothesketch,soyoudon’twanttooverwritetheexample.SavethesketchbyselectingFile ⇒ SaveAs.NamethefileBlinkingFunctions.ino.

TakealookatyournewBlinkingFunctionssketch(yourcopyoftheBlinkexamplesketch).Inthesketch,mostoftheactionhappensintheloop()function:

//thelooproutinerunsoverandoveragainforever:voidloop(){digitalWrite(led,HIGH);//turntheLEDon

delay(1000);//waitforaseconddigitalWrite(led,LOW);//turntheLEDoff

delay(1000);//waitforasecond}

Youcancreateyourownfunctionthatdoesthesamethingasthefourlinesofcodeintheprecedingloop()function.Butbeforeyoudothat,holdfire!ThereareacoupleofimportantthingsIwanttohighlightaboutwritingafunctionfirst.

Afunctionalwayshasthreepiecesofinformation,andyouneedtotypeallthreeofthesebeforethefirstcurlybracketofeachpair(seeFigure4-2).

FIGURE4-2Theanatomyofafunction

Thefirstpieceofinformationisthetypeofdatathatwillbeoutputorreturnedfromthefunction.Inmostofthecodeyoucreateinthisbook,thisisjustvoid,meaningthatthereisn’tanythingreturned.Ifthereisdatathatisoutputorreturnedfromthefunction,thedatatypeislistedinsteadofvoid.Forexample,ifyourfunctioncomputesananswerasaninteger,thereturndatatypeisintinsteadofvoid.

Youmighthavenoticedthatthetermvoidkeepsappearingbeforesetup()andloop().Thetermjustmeansthatthefunctiondoesn’treturnanythingwhenit’sfinished.Forexample,youmightwriteafunctionthatcalculatesthesumofthreenumbers,intendingtheanswertothecalculationreturnedtothepositionwhereyoucalledthefunctionsoyoucansavetheanswerinavariable.Thisvariablemightbeanint.Forfunctionsthatsimplyturnonandofflights,noadditionalinformationisneededwhenthefunctionfinishes,sothereturntypeisvoid.

Thesecondbitofinformationisthenameofthefunction.TherulesfornamingafunctionaresimilartonamingavariableasdescribedinAdventure2:

Youcan’thavespacesinthename,butyoucanusenumbersandletters.Youcan’tstartthenamewithanumber.Youmakethefirstletterlowercase.

Youmightfindthelastpieceofinformationalittlehardtofind;it’stheroundbrackets(alsoknownasparentheses).Whenthereisn’tanythingbetweenthefirst(andthesecond),itmeanstherearen’tanyinputarguments.Youcanpassinformationtoafunctionusinginputarguments;andyouseehowtodothatlaterinthissection.

Returntothesketchandgototheverylastlineofcode—theoneaftertheclosingbracketoftheloop()function.Addthefollowingcode,makingsureitisn’tinsideanyotherfunction.(Inotherwords,makesurethatthecodeyou’readdingisnotinsidetheparenthesesorbracketsofanyotherfunction.)

//turnontheLEDfor1second//thenofffor1secondvoidblinkOnce(){digitalWrite(led,HIGH);//turntheLEDon

delay(1000);//waitforaseconddigitalWrite(led,LOW);//turntheLEDoff

delay(1000);//waitforasecond

}

YouhavejustcreatedanewfunctioncalledblinkOnce().Itdoesn’ttakeanyinputarguments(becausethe(and)areemptyafterthefunctionname),anditdoesn’treturnanything(becauseitlistsvoidbeforethefunctionname).Insidethefunction,itblinkstheLEDonfor1secondandthenofffor1second.

It’sagoodhabittoaddacommentatthetopofyourfunctionthatexplainswhatthefunctiondoes.Youcanuse//atthebeginningoftheeachlineor/*and*/atthebeginningandendofaparagraph.Itmightseemunnecessarywhenit’sasimplefunction,butifyoualwaysdoit,thenyou’llalwaysremembertoaddcommentsformorecomplicatedfunctions.Whenyousharecodethat’swellcommented,otherswillbeabletounderstandit,too.

Next,changetheoriginalloop()functionsoitonlycallsyournewfunction:

//thelooproutinerunsoverandoveragainforever:voidloop(){blinkOnce();

}

UploadthesketchtotheArduinoboardbyconnectingyourArduinoUnoandclickingtheUploadbutton.YoushouldseetheLEDblinkonandoffjustliketheoriginalBlinksketchdidinAdventure1.

Nowyou’regoingtoseewhatfunctionscanreallydo.You’regoingtoaddalittlemorecodethataddsavariabletothefunctiontocontrolthespeedoftheblink.

ChangeyourblinkOnce()functiontothefollowing(thechangesareinbold):

//turnontheLEDfortimepassedinargument//thenofffortimepassedinargumentvoidblinkOnce(inttime){digitalWrite(led,HIGH);//turntheLEDon

delay(time);//wait

digitalWrite(led,LOW);//turntheLEDoff

delay(time);//wait}

Byaddingavariablebetweenthe(and),yourprogramissayingthatthefunctionneedssomeadditionalinformationinordertorun.Thisiscalledanargument,andwithityoucanpassinformationdirectlyfromonefunctiontoanother.

ThismeansyouneedtoincludeanargumentwhenyoucallblinkOnce()intheloop()function.Changetheloop()functionagainsoitmatchesthefollowingcode:

//thelooproutinerunsoverandoveragainforever:voidloop(){blinkOnce(1000);

}

Whenyouaddanargumentof1000,theLEDshouldblinkonandoffjustasitdidbefore—onfor1secondandthenofffor1second.

CHALLENGE

MaketheLEDblinkonfor1secondandthenofffor1second,thenonfor5secondsandofffor5seconds.You’llneedtocallthe()functiontwiceintheloop()functionwithdifferentarguments.

UsingforLoopsAnotherusefulwaytoorganiseyourcodeistorepeatsomethingacertainnumberoftimes.Forexample,insteadofgoingtoallthetroubleofwritingafunctionfivetimesinarow,youcanuseanotherpieceofcodetodoitforyou.Aforloopisonewayofdoingthat.

Aforloopneedsthreekeypiecesofinformation,asshowninFigure4-3.

FIGURE4-3Theanatomyofaforloop

Thefirstpieceofinformationisthestartingcondition.Aforloopbeginswithastartingvalueforavariable.Thisisusuallyjustatemporaryvariablethatisonlyusedintheforloop.Itcanbecalledanythingthatyouwouldlike,butprogrammerstendtocallthisvariablei.

Thesecondpieceofinformationiswhatisneededinorderforthelooptostop.Thisisphrasedasatrueorfalsequestionandisoftencheckingifthevariablehasbecometoobig.Itmightbesomethinglikei<10.

Thelastpieceofinformationiswhathappenstothevariableaftereachloop.Thevariableneedstogetfromitsstartingvaluetosomethingthatcausesthelooptoend;otherwiseitwouldjustgoonforeverandyourprogramwouldnevergetpasttheforloop.Thispieceofinformationisusuallyi++,whichsimplymeansadd1toiandsavethenewnumberiniagain.

Makeanewsketch(eitherbyclickingtheNewbuttonintheArduinoIDEorgoingtoFile ⇒ New)andtypethefollowingcode:voidsetup(){Serial.begin(9600);}

voidloop(){inti;for(i=0;i<10;i++){//forloopthatcountsfrom0to9Serial.println(i);//printthecurrentvalueofidelay(1000);//waitfor1second}

delay(3000);//waitfor3seconds}

UploadthecodetoyourArduinoboardandthenopentheSerialMonitorintheArduinoIDEbyclickingontheSerialMonitorbuttonorgoingtoTools ⇒ SerialMonitor.Youshouldseetheforloopcountingfrom0to9overandoveragain.

Trychangingi++toi+=2.Whatdoyouthinkishappening?

GettingMoreOutputswithShiftRegistersIntheearlieradventuresinthebook,youbuiltcircuitswithsomeessentialelectricalcomponents.Thingslikeresistorsarethemostbasiccomponentsbutyoucancombinethemwithotherbasiccomponentstoformmorecomplicatedcircuits.However,youdon’tnecessarilyhavetospendalotoftime(anduseupalotofspace)buildingacomplicatedcircuit.Youcansometimesbuyachipthathasalreadybeenputtogetherforyou,containingmorecomplicatedcircuits.Thesechipsarecalledintegratedcircuits,orICsforshort.

Integratedcircuits(ICs)arecircuitscontainedwithinasinglechip.Thesamecircuitcanbeputintodifferentshapedchips,calledpackages.Whenworkingwithabreadboard,youwantwhatisknownaDIPorDILpackage.That’stheshapethathaslegsthatfitintoabreadboard.

Chipscomeindifferentpackages.Thatjustmeansdifferentsizesandshapes.Whenworkingwithbreadboards,youwillwanttousecomponentsthataredualin-linepackages(shortenedtoDIPorDIL).Theyhavelegsthatfitintoabreadboard.Theothertypeofcomponentpackageisasurface-mountdevice(SMD).SMDpackagesareverysmallandaredesignedtobeeasilyplacedoncircuitboardsinfactories.Theyaremuchmoredifficulttouseincircuitsbuiltathomewithbreadboards.MostofthecomponentsonyourArduinoUno(allthosetinyblackrectanglesandeventheLEDs)areSMDpackages.

Adualin-linepackage(DIPorDIL)isonepossibleshapeofanICchip.Ithastworowsoflegsthatcanfitintoabreadboard.

Asurface-mountdevice(SMD)isonepossibleshapeofanICchiporothercomponentsuchasaresistor.Itismadeforsolderingontoaflatsurfacewithoutanylegsbeinginsertedintoholesonacircuitboard.

Youcanusemultiplechipsinthesamecircuittodothesamethingoverandover.YoucanthinkofICsasbeingthefunctionsofelectroniccomponents.

InthisadventureyouaregoingtouseanICcalledashiftregister.Theshiftregisteryou’llusetakesthreeinputsthatcontrolwhathappensoneightoutputs.SowithjustthreepinsfromtheArduinoboard,youwillbecontrollingeightdifferentLEDs.Evenbetter,youcanattachashiftregistertoanothershiftregisterinachain.SoyoucankeepaddingeightmoreLEDswhilestillonlyusingthreepinsonyourArduinoboard!

Ashiftregisterisadevicethatcancontrolmultipleoutputswithrelativelyfewinputs.ItiscommonlyusedtocontrolalargenumberofLEDs.

HowaShiftRegisterWorksThethreeinputsthatashiftregistertakesaretheCLOCK,theDATAandLATCH.

ClockTheCLOCKisthedrumbeatofthecircuit.MessagesarebeingsentfromtheArduinototheIC.YoucanthinkoftheArduinoassingingasongwiththeIC.InorderfortheICtobeabletofollowalong,theArduinoandICneedtosingatthesametempo.TheCLOCKisaseriesofHIGHandLOWvalues(seeFigure4-4)thatpulsetolettheICknowwhennewinformationisbeingtransmitted,likethedrumbeatthatletstheICfollowalongwiththeArduino.

FIGURE4-4TheCLOCKsignal

DataTheDATAiswhatyouwanteachoftheoutputs(LEDs)tobesetto,whichwillbeeitherHIGHorLOW.AshiftregistercancontroleightLEDs.TheArduinoUnosendstheshiftregisterthevalueoftheLEDsonebyonelikeso:

1. ThefirstLEDvalueissenttotheshiftregisterfromtheArduinoUno.Theshiftregisterssetsthefirstoutputpintobethatvalue.

2. ThesecondLEDvalueissenttotheshiftregister.TheshiftregistersetthesecondoutputpintothevaluethatwassavedinthefirstoutputpinandthensetsthefirstoutputpintothemostrecentvaluesentbytheArduinoUno.

3. TheArduinoUnosendsathirdLEDvaluetotheshiftregister.Thethirdoutputpinnowissettowhatthesecondoutputpinwaspreviouslysetto;thesecondoutputpinissettowhatthefirstoutputpinwassetto;andthefirstoutputpinissettothenewvalue.

4. TheArduinoUnokeepssendingnewvaluestotheshiftregister.Eachtimeanewvaluecomesin,theshiftregistershiftsallthepreviouslysavedvaluesforeachoutputpindowntothenextpin.Thenewestvaluesetsthefirstoutputpin.

Eachtimeyousendtheshiftregisteranewvalueforanoutput,thepreviousvaluegetsshiftedtothenextoutput.That’swherethenameshiftregistercomesfrom!

Whenyouhavefinishedsendingoutputvalues,youneedtotelltheshiftregisterthatyouhavefinishedsoitcanturnonorofftheoutputpinsofthechip—whichiswhatLATCH

does.

LatchThefinalinputisthesignalthattellstheshiftregistertoeitherlistenformoreinformationorgoaheadandoutputtheinformationithas.WhentheLATCHpinisLOW,theICislistening;whenitchangestoHIGH,theICstartsdoingandtheoutputvaluesaresentout.WhenLEDsareconnectedtotheshiftregister,theywillturnonoroffaccordingtothenewvaluesstoredintheshiftregisterwhentheLATCHchangestoHIGH.

Figure4-5illustrateshowthethreeinputsworktogethertocontroltheshiftregister.

FIGURE4-5Howashiftregisterworks

MakingtheConnectionsforaShiftRegisterThefirstthingtodoisbuildyourcircuit.Startbyputtingyourshiftregisterchiponyourbreadboard.Thechipfitsoverthegapinthemiddleoftheboard.Youmayneedtobendthelegsalittletogetthechiptofitnicelyintotheholes.Noticethatthere’salittledotprintedonacornerorahalfcirclecutoutfromoneendofthechip:thisisthetopofthechip,andit’sveryimportantthatthechipisinthesameorientationasthediagramshowninFigure4-6.

ThelegsoftheICcanbedelicate,sotakecarewhenbendingthem.Alsotakecarewhenremovingthechipfromthebreadboardasitcanbeeasytoaccidentallybendthelegs.

FIGURE4-6Pin-outdiagramfortheshiftregister

Youarereadytostartbuildingyourshiftregistercircuit.Figure4-6isapin-outdiagramthatshowstheshiftregisterlabelledwiththepinnumbersforthechipandshowswhatconnectstoeachpinonthechip.NotethatthecolourscorrespondtothewirecoloursinFigure4-7.Nowyouneedtomakethefirstoftheconnectionsbyfollowingthesesteps(don’tconnectyourArduinoUnotoyourcomputeryet):

1. UseajumperwiretoconnectoneofthelongrowsalongthebottomofyourbreadboardtoaGNDpinontheArduinoUno.Ifyourbreadboardisalabelledwithablueorblacklineora-,connectittothatrow.

2. Useajumperwiretoconnecttheotherlongrowalongthebottomofyourbreadboardtothe5VpinontheArduinoUno.

3. Usetwojumperwirestoconnecteachofthelongrowsalongthebottomofthebreadboardtothelongrowsalongthetop.Ifyourbreadboardislabelled,connecttheredor+totheotherrowwithredora+thenconnecttheremainingtwolongrowstoeachother.

4. UsetwojumperwirestoconnecttheshortrowsconnectedtoPin8andPin13onthe

shiftregistertothelongrowonthebreadboardconnectedtoground.5. UsetwojumperwirestoconnecttheshortrowsconnectedtoPin10and16onthe

chiptothelongrowconnectedto5V.6. UseajumperwiretoconnecttheshortrowconnectedtoPin14ontheshiftregister

toPin11ontheArduinoboard.7. UseajumperwiretoconnecttheshortrowconnectedtoPin11ontheshiftregister

toPin12ontheArduinoboard.8. UseajumperwiretoconnecttheshortrowconnectedtoPin12ontheshiftregister

toPin8ontheArduinoboard.

Whenyou’vefinished,yourcircuitshouldlooklikeFigure4-7.Noticetheshiftregisterchipinthemiddle,facinginthecorrectdirection.

FIGURE4-7Firstconnectionsfortheshiftregister

AddingLEDsNowit’stimetoaddtheLEDs.Ifyouhaveasecondbreadboard,youmightfinditeasiertohavetheshiftregisterononeboardandtheLEDsonanother,butyoucanalsofiteverythingonasinglebreadboard.

EachoftheLEDsneedsacurrent-limitingresistor,justlikewhenaLEDishookedupdirectlytoapinontheArduinoboard.Eachoutputoftheshiftregisterisconnectedtoacurrent-limitingresistorandthentoaLED,whichisthenconnectedtoground.

UsingFigure4-8asaguide,followthesestepstoaddyourLEDsandresistors:

1. Placetheshortlegsof8LEDsinthelongrowalongthetopofthebreadboardthatisconnectedtoground.

2. PlaceeachofthelonglegsoftheLEDsintotheirownshortrowsonthebreadboard—wherevertheyeasilyfitisfineaslong(asnothingelseisalreadyconnectedtotherow).

3. PlaceonelegofaresistorintothesameshortrowsasthelonglegsoftheLEDs.4. Bendtheresistorsoverthegapinthemiddleofthebreadboard,andinsertthefree

legsoftheresistorsintotheshortrowdirectlyontheothersideofthegap.5. Useeightjumperwirestoconnecteachresistortoanoutputpinontheshiftregister

—pins15and1through7.UseFigures4-6and4-8asguides.

FIGURE4-8Thefullcircuitfortheshiftregister

Double-checkthatyourconnectionsarecorrect—gothrougheachstepagain.Whenareyousureeverythingisintherightplace,youarereadytopowerthecircuitbyconnectingtheArduinoUnotoyourcomputer.

Yourchipshouldnevergethot!Ifitevergetshot,somethingispluggedinwrong,soyoumustremove

thepowerimmediately.Thechipmightbedamagedandmayneedtobereplaced.Ifitevermakesapoppingsoundandevensmokesalittle,itdefinitelyneedstobereplaced.Besuretocheckoveryourcircuitagainandfindthemistakebeforeputtinginanewchip,oryouwilljustdamagethenextchipinthesameway!

WritingtheCodeCreateanewsketchbyclickingontheNewbuttonintheArduinoIDEorgoingtoFile ⇒ Newandenterthefollowingcode:

voidsetup(){

}

voidloop(){

}

Attheverytopofyoursketch,beforethesetup()begins,addthefollowingvariables:

//Pinconnectedtolatchpin(ST_CP)of74HC595intlatchPin=8;//Pinconnectedtoclockpin(SH_CP)of74HC595intclockPin=12;//PinconnectedtoDatain(DS)of74HC595intdataPin=11;

TheyarethethreepinsfortheLATCH,CLOCKandDATAconnectionstotheshiftregister.

Next,typethefollowingcodebetweenthe{and}ofsetup():

//setpinstooutputbecausetheyareaddressedinthemainlooppinMode(latchPin,OUTPUT);pinMode(dataPin,OUTPUT);

pinMode(clockPin,OUTPUT);

Eachofthoselinesofcodesetupthepinstobeoutputsthatsendoutdatatotheshiftregister(asopposedtoreadingindata).

Lastly,typethefollowingcodebetweenthe{and}ofloop():

//loopthrough0to256inti;for(i=0;i<256;i++){//turnofftheoutputsothepinsdon’tlightup//whileyou’reshiftingbits:digitalWrite(latchPin,LOW);shiftOut(dataPin,clockPin,LSBFIRST,i);

//turnontheoutputsotheLEDscanlightup:digitalWrite(latchPin,HIGH);delay(300);}

Yourcompletesketchshouldnowlooklikethis:

//Pinconnectedtolatchpin(ST_CP)of74HC595

intlatchPin=8;//Pinconnectedtoclockpin(SH_CP)of74HC595intclockPin=12;//PinconnectedtoDatain(DS)of74HC595intdataPin=11;

voidsetup(){//setpinstooutputbecausetheyareaddressedinthemain looppinMode(latchPin,OUTPUT);pinMode(dataPin,OUTPUT);

pinMode(clockPin,OUTPUT);}

voidloop(){//loopthrough0to256inti;for(i=0;i<256;i++){//turnofftheoutputsothepinsdon’tlightup//whileyou’reshiftingbits:digitalWrite(latchPin,LOW);shiftOut(dataPin,clockPin,LSBFIRST,i);

//turnontheoutputsotheLEDscanlightup:digitalWrite(latchPin,HIGH);delay(300);}}

Youcandownloadthesketchesinthischapterfromthecompanionsite(www.wiley.com/go/adventuresinarduino).

UploadthesketchtoyourArduinoUno.YourLEDsshouldstartturningonandoff.

DIGGINGINTOTHECODE

Sowhatisgoingonintheloop()function?Theloop()functionusesaforloopasdescribedearlierinthisadventure.Insidetheforloop,youcallafunctionnamedshiftOut().ThisisafunctionthattheArduinoknows,andittakesfourarguments.Inthefirstargumentitsendsoutanumberthroughthegivenpin(dataPin),usingthepingiveninthesecondargumenttosendtheCLOCKsignal(clockPin).Thethirdargumentusesakeywordtoindicatewhetherthenumberbeingsentoutstartswiththefirstdigitorthelastdigit(LSBFIRST).Thelastargumentisthenumberbeingsentout.Herethenumberbeingsentoutisstoredini,whichiscontrolledbytheforloop.Itstartsati=1andstopsafteri=255.

shiftOut(dataP0in,clockPin,LSBFIRST,i);

BeforeshiftOut()iscalled,thelatchPinissettoLOW.Thistellstheshiftregistertostopdoingandstartlistening.ThenewvaluesfortheLEDsarethensentintheshiftOut()function,andthenthelatchPinissettoHIGH.Thattellstheshiftregistertostoplisteningandstartdoing.ItthenturnsonandofftheLEDsaccordingtothenewvaluesitjustreceived.

Youmayhavespottedsomethingalittleweirdinthecode.Whydoestheforloopstartat0andcountupto256?Doesn’tthatseemalittlestrange?

Computersliketostartcountingat0.Ashumans,weusuallyskipover0andstartcountingat1,but0istypicallythestartingpointforcomputers.That’swhytheforloopstartsat0.

Andwhyareyouusing255asthemaximumvalue?TheshiftregisteriscontrollingeightLEDs.EachLEDcaneitherbeonoroff,sothat’stwopossiblestatesforeveryLED.Ifa0representsanLEDoffanda1representsanLEDon,youcandescribetheonandoffstatesofalltheLEDswithasinglenumber.11111111wouldbealltheLEDson.10000001wouldbealltheLEDsoffexceptthefirstandlastones.

Thesenumbersarespecialbecausetheydon’tuseallthepossibledigitsbetween0and9,butinsteadonly0and1.Numbersthatuseallthedigitsfrom0to9arecalleddecimalnumbers(whatyouthinkofasnormalnumbers),andnumbersthatcountusingonly0and1arecalledbinary.ThenumberbeingsentoutthedataPinisrepresentedinbinary.

Thesketchthatyoujustwroteisabinarycounter;itshowsyouinlightshowtocountfrom0to255inbinary(0to11111111).

Abinarynumberusesonlythedigits0and1,asopposedtodecimal,whichusesthedigits0through9.Binaryisalsoreferredtoasbase-2.Decimalisreferredtoasbase-10.

Figure4-9showsyouhowtoconvertbinarynumbersintodecimalnumbers.Atthispoint,youdon’tneedtoworrytoomuchaboutthisiflearningaboutdifferentwaysofrepresentingnumbersdoesn’tseemlikemuchfun,butifyoulikesecretcodesandmessages,itmaybeatopicthatyouwillfindveryinteresting.

FIGURE4-9Howtoconvertfromabinarynumbertoadecimalnumber

CHALLENGE

CalculatethedecimalnumberfromthebinarypatternshowninFigure4-10.

FIGURE4-10Howwouldthisbinarypatternberepresentedbyadecimalnumber?

Asingledigitinabinarynumberiscalledabitandagroupof8bitsiscalledabyte.Allcomputingisbasedonbitsandbytes.Ifyou’reinterestedinlearningmore,youcanstartbylookingupmoreinformationonbitsandbytesathttp://en.wikipedia.org/wiki/Bitandhttp://en.wikipedia.org/wiki/Byte.

AddingMoreShiftRegistersToaddanothershiftregister,youneedtoputasecondIConthebreadboard(ifyou’reusingabigbreadboard)oronasecondbreadboard(ifyou’reusingtwosmallbreadboards):

1. Followthestepsyoufollowedearliertoconnecttheshiftregisterto5VandGND.Ifyouareusingasecondbreadboard,besuretoconnectthelongrowsofthatbreadboardtothelongrowsofthefirstbreadboard.

2. InsteadofconnectingPins12,14and11ontheshiftregistertoPins8,11and12ontheArduinoUno,connectPins11and12ofthesecondshiftregistertoPins11and12onthefirstshiftregister.ThisconnectsLATCHandCLOCKfromthefirstshiftregistertothesecondone,asshowninFigure4-11.

3. TheDATAforthesecondshiftregisterdoesn’tcomefromtheArduinoboard,butfromPin9ofthefirstshiftregister.UseajumperwiretoconnectPin14ofthesecondshiftregistertoPin9ofthefirstshiftregister.

4. Followthesamestepsinthe“AddingLEDs”sectionforaddingtheLEDsthefirstshiftregistertoconnect8moreLEDstothesecondshiftregister.

FIGURE4-11Addingasecondshiftregister

Whenyourcircuitisbuilt,youneedtochangeyoursketchsothatitcontrolstwoshiftregistersinsteadofonlyone.Makethechangesshowninboldtotheloop()functionofyoursketch:

voidloop(){//loopthrough0to256inti;for(i=0;i<256;i++){//turnofftheoutputsothepinsdon’tlightup//whileyou’reshiftingbits:digitalWrite(latchPin,LOW);

//sendtosecondshiftregistershiftOut(dataPin,clockPin,LSBFIRST,i);//sendtofirstshiftregistershiftOut(dataPin,clockPin,LSBFIRST,i);

//turnontheoutputsotheLEDscanlightup:digitalWrite(latchPin,HIGH);delay(300);}}

UploadthesketchtoyourArduinoUnoandwatchall16ofyourLEDsturnonandoff.

BuildingYourNameinLightsDifferentelectricalcomponentscanperformthesamefunctionbutlookverydifferentfromeachother.LEDsareanexampleofthis;forexample,youcanuseLEDsindifferentcolourswithouthavingtochangethecircuit,althoughyoustillneedacurrent-limitingresistorandaconnectiontoapositivevoltageandground.

LEDsaremeasuredbytheirwidthandyoucanalsobuythemindifferentsizes.Youareprobablyusing5mmLEDsbutyoucangetthemisallsizessoyoumightliketotrythemin3mmor10mm.The10mmLEDsworknicelyinthisproject,butyoucanusewhateversizeandcolourthatyouthinklooksgood.

Inthisprojectyoucanlightupasmanyas24LEDs.YoucandecidehowyouwanttoarrangethoseLEDsandusethemtoembellishacarnival-stylelettersign.You’regoingtocreateyourowndesignforafantasticsignandputyournameinlights(seeFigure4-12).Youcanchoosewhatyou’dliketospell.Itcanbeyourname(orjustinitialsifyournameisquitelong)oranyotherword—likeLED!

FIGURE4-12Yourname(oranyotherword)inlights!

Youwillchoosewhatlettersyouwouldliketomakeandcutthemoutofcardboard.Thenyoucandecidewhereyouwanttoplacethe24LEDsandaddthemtoyourletters.

Youcanwatchavideoofhowtobuildacarnival-stylelettersignonthecompanionwebsiteat

www.wiley.com/go/adventuresinarduino.

WhatYouNeedFollowingisalistofwhatyouneedtobuildyoursign.RememberthatAppendixAlistsplacesthatyoucanbuytheelectroniccomponentsshowninFigure4-13.

AcomputerAnArduinoUnoAUSBcableAbreadboard(youmayneedseveralifyoubuildalotofletters)57jumperwires24LEDs24220Ωresistors374HC595shiftregisterICs(1forevery8LEDs)Somecardboard(cuttingupoldcardboardboxesworkswell)SomewireSomesolderPaintorcolouredpaperfordecorationAsolderingironMaskingtapeScissorsorautilityknifeApencil,screwdriverorholepunch

FIGURE4-13Theelectroniccomponentsyouneedtobuildyournameinlights

UnderstandingtheCircuitThecircuitforthisprojectisverysimilartotheoneyoubuiltearlierinthischapterusingtwoshiftregisterswith16LEDs.Youcanadduptothreeshiftregistersand24LEDs.Youneedoneshiftregisterforevery8LEDs.

Therearealotofconnectionstomake,souseFigure4-14asaguidetowhatshouldbeconnected.Remember,onlythelinesthatintersectwithacirclearethewiresthatareconnectedtoeachother.

FIGURE4-14Circuitschematicforthreeshiftregisters

PrototypingonaBreadboardAlwayscheckthatyourcircuitisworkingbeforeyoustartsoldering!Prototypethecircuitwiththreeshiftregisters.Youmayneedtousemultiplebreadboards.Followthestepsinthe“AddingMoreShiftRegisters”sectiontosetupthreeshiftregisters.Pin14ofoneshiftregisterwillbeconnectedtoPin11ontheArduinoUno.Fortheothertwoshiftregisters,Pin14onbothofthemconnectPin9ofthenextshiftregister.UseFigure4-11asaguideandaddathirdshiftregistertothesecondshiftregisterinthesamewayyouconnectedthesecondshiftregistertothefirstshiftregister.ConnecteightLEDstoeachoftheshiftregistersusingthestepsin“AddingtheLEDs”section.

WritingtheCodeCreateanewsketchbyclickingontheNewbuttonintheArduinoIDEorgoingtoFile ⇒ New.Typethefollowingcodetobeginwritingyoursketch:

voidsetup(){

}

voidloop(){

}

Atthetopofthesketch,beforethesetup(),addthefollowingvariables:

//Pinconnectedtolatchpin(ST_CP)of74HC595intlatchPin=8;//Pinconnectedtoclockpin(SH_CP)of74HC595intclockPin=12;//PinconnectedtoDatain(DS)of74HC595intdataPin=11;

//numberofshiftregistersusedintnumRegisters=3;

//firstpatterntobedisplayedintpattern1=85;//secondpatterntobedisplayedintpattern2=170;

Insidesetup(),setthepinmodesandcallafunction,setLEDs(),thatyouwillwritelater.Addthefollowingcode:

//setpinstooutputbecausetheyareaddressedinthemainlooppinMode(latchPin,OUTPUT);pinMode(dataPin,OUTPUT);

pinMode(clockPin,OUTPUT);

//startwithallLEDsoffsetLEDs(0);

Insidetheloop()typethefollowingcodetosendablinkingpatterntotheLEDs:

//turnonLEDsinthepattern01010101setLEDs(pattern1);//wait1secdelay(1000);//turnonLEDsinthepattern10101010setLEDs(pattern2);

//wait1secdelay(1000);

TheonlyfunctionmissingisthesetLEDs()function.Thisisanewfunctionthatyouwriting—itisn’tincludedintheArduinoIDE.Typethefollowingcodeaftertheloop()(afterthe})andyoucanreadmoreaboutwhatitisdoingintheDiggingintotheCodesidebar:

//sendspatterntoshiftregisterfor//whichLEDstoturnonandoffvoidsetLEDs(intlightPattern){//turnofftheoutputsothepinsdon’tlightup//whileyou’reshiftingbits:digitalWrite(latchPin,LOW);

inti;for(i=0;i<numRegisters;i++){//sendsoutthepatternonceforeachshiftregistershiftOut(dataPin,clockPin,LSBFIRST,lightPattern);}

//turnontheoutputsotheLEDscanlightup:digitalWrite(latchPin,HIGH);delay(300);}

Followingisthefullsketch,butyoucanalsodownloaditfromthecompanionsiteatwww.wiley.com/go/adventuresinarduino.

//Pinconnectedtolatchpin(ST_CP)of74HC595intlatchPin=8;//Pinconnectedtoclockpin(SH_CP)of74HC595intclockPin=12;//PinconnectedtoDatain(DS)of74HC595intdataPin=11;

//numberofshiftregistersusedintnumRegisters=3;

//firstpatterntobedisplayedintpattern1=85;//secondpatterntobedisplayedintpattern2=170;

voidsetup(){//setpinstooutputbecausetheyareaddressedinthemainlooppinMode(latchPin,OUTPUT);

pinMode(dataPin,OUTPUT);

pinMode(clockPin,OUTPUT);

//startwithallLEDsoffsetLEDs(0);}

voidloop(){//turnonLEDsinthepattern01010101setLEDs(pattern1);//wait1secdelay(1000);//turnonLEDsinthepattern10101010setLEDs(pattern2);//wait1secdelay(1000);}

//sendspatterntoshiftregisterfor//whichLEDstoturnonandoffvoidsetLEDs(intlightPattern){//turnofftheoutputsothepinsdon’tlightup//whileyou’reshiftingbits:digitalWrite(latchPin,LOW);

inti;for(i=0;i<numRegisters;i++){//sendsoutthepatternonceforeachshiftregistershiftOut(dataPin,clockPin,LSBFIRST,lightPattern);}

//turnontheoutputsotheLEDscanlightup:digitalWrite(latchPin,HIGH);delay(300);}

ConnectyourArduinoUnotoyourcomputeranduploadthecode.Yourlightsshouldstartflashing.

DIGGINGINTOTHECODE

Thevariablesatthetopofthecodeandmostofthesetup()shouldlookfamiliartoyou;theyarethesameaswhatyouusedearlierinthisadventure.Thereisonenewvariable:numRegisters.Itiscurrentlysetto3,butifyouwouldliketousefewershiftregisters,youcanchangeittothenumberyouareusing.

There’salsoanewfunction:setLEDs().Thisfunctionisdefinedunderneathloop().Ittakesoneargument:thepatternofLEDstolightup(pattern1orpattern2).

Thepatternisdescribedbyadecimalnumber.Forpattern1,itisthenumber85indecimal,whichis01010101inbinary,soitturnsoneveryotherLEDofeachsetofeightLEDs.TheotherLEDpatternispattern2,whichis170indecimalor10101010inbinary.Itistheoppositeofpattern1—itturnsontheLEDsthatwereoffinpattern1andturnsofftheLEDsthatwereon.SowhentheLEDsalternatebetweenpattern1andpattern2,itcreatesaflashingpattern.

Wantyoursigntolightupinadifferentpattern?It’snottoodifficulttocreateyourown.Writeoutthepatternasasequenceofeight0sand1sandthencalculatewhatthatnumberwouldbeindecimal.Youcanalsouseanonlinecalculatortohelpconvertbetweenbinaryanddecimal;trywww.mathsisfun.com/binary-decimal-hexadecimal-converter.htmlorwww.binaryhexconverter.com/binary-to-decimal-converter.

MakingtheLightsYourfirst—andbiggest—decisionistochoosethelettersyouwillcreate.Remember,youonlyhave24LEDstodecorateyoursignswith.YouneedtodecidewhatlettersyouwouldliketomakeandwheretheLEDswillbeplaced.

1. Traceyourlettersontocardboard.Cardboardfromoldboxesworkswell.Useapairofscissorsorautilityknifetocutouttheletters.

2. Ifyouwanttodecorateyourletterswithpaintorpaper,goaheadanddothatnow.3. Whenanypaintorglueusedtodecorateyourlettersaredry,useatooltopokeahole

inthecardboardletterswhereyouwanttoplaceeachLED.Apencilorscrewdrivercanworkwell.MakesuretheholeisjustbigenoughtosnuglyholdtheLEDinplace.Atthispointyou’rejustdeterminingtheplacementoftheLEDs.Youinsertthelightsintotheholesafteryouhavethewiressoldered.YoushouldnowhaveletterssimilartotheonesinFigure4-15.

FIGURE4-15CardboardletterswithholesforLEDs

SolderingtheWiresUsethefollowingstepstosolderyourcircuit:

1. SolderaresistortothelonglegofeachLED.TwistthelegsoftheresistorandLEDtogethersothattheydon’teasilycomeapartandthensolderthem.

Alwayshaveanadultnearbywhenyouaresoldering.Adventure2hassomemoretipstohelpyoustaysafewhenyousolder.

2. PlacetheLEDsintheirholesinthecardboardletters.BendtheshortlegsofeachoftheLEDstowardsthenextLED(useFigure4-16asaguide).IftheshortlegofanLEDdoesn’treachtheLEDnexttoit,cutapieceofwirethatreachesfromthatLEDtothenext.SoldereitherthewiretoeachLEDortheshortlegofthefirstLEDdirectlytothenext.RepeatforalltheLEDs.YoushouldhaveoneshortlegofanLEDleftoneachletter.TherestoftheshortlegsoftheLEDsshouldbeconnectedtoeachother.

3. YouuseabreadboardtoconnectyourshiftregisterstotheLEDsandtheArduinoUno.DecidewherethebreadboardandArduinoUnowillbeplaced.Theycouldbetapedtothebackofaletterorcouldrestonthetablenexttotheletters.

4. Cut24piecesofwirethatreachfromeachoftheresistorssolderedtotheLEDstothebreadboard.Youmightwanttohidethewiresbytapingthemalongthebackoftheletters,sobesuretocutthemlongenoughforthatifthat’swhatyouwouldliketodo.

5. Stripabout½”fromeachendofallthewiresyoujustcut.SoldereachwiretoitsLED.

6. CutawirethatreachesfromtheremainingshortLEDlegoneachlettertothebreadboard.Youneedoneforeachletter.

7. Stripabout½”fromeachendofthewiresyoujustcut.SoldereachwiretoitsshortLEDlegoneachletter.

FIGURE4-16SolderedLEDsandresistors

InsertingtheElectronicsWhenyou’vefinishedsolderingallyourLEDs,justpopthemthroughtheholesinyourletters.Youmightneedtoaddalittleglueiftheydon’tstayput.ThenyouarereadytobuildyourshiftregistercircuitsontoonebreadboardasshowninFigure4-17:

1. Followthesamestepsyouwentthroughwhenbuildingtheprototypecircuit.Youconnectthe5V,ground,CLOCK,LATCHandDATAlinesasyouhavedonepreviously.

2. TheresistorsaresolderedtotheLEDs,sotheydon’tneedtobeplacedonthebreadboard.Insteadconnectthewiresthatyousolderedtotheresistorstothepinsontheshiftregisters.SeeFigure4-16forguidance.

3. ConnectthewiresfromtheshortlegsofeachLEDtogroundonthebreadboard.4. ConnectyourArduinoUnotoyourcomputerortoapowersupply.

PowerupyourArduinoboardandheypresto!Yournameisinlights!

FIGURE4-17Backoflights

FurtherAdventureswithShiftRegistersYounowhaveagreatdisplaytotryoutdifferentlightanimations.Trywritingyourownfunctionswithlightpatternsofyourowndesign.

Youmightwanttocheckoutsomeofthesetutorialsonline:

http://arduino.cc/en/tutorial/ShiftOut

https://learn.adafruit.com/adafruit-arduino-lesson-4-eight-leds/the-

74hc595-shift-register

Intheprojectyoujustcreated,youaresendingadecimalnumbertoshiftOut(),whichthenturnsthenumberintoabinarynumbertotelleachoutputpinwhetheritshouldbeHIGHorLOW.Youcanreadmoreaboutbinarynumbersathttp://en.wikipedia.org/wiki/Binary-coded_decimal.

ArduinoCommandQuickReferenceTable

Command Description

voidTellsthecomputerthatnodatawillbereturnedbyafunctionwhenitfinishes.Seealsohttp://arduino.cc/en/Reference/Void.

shiftOut()SendsaseriesofHIGHandLOWvaluesintimewithaCLOCKsignal.Seealsohttp://arduino.cc/en/Reference/ShiftOut.

AchievementUnlocked:Skillfulengineerofshiningsigns!

IntheNextAdventureInthenextadventure,youwilllearnhowtoaddaspeakerandplaymusictotransformyourArduinointoanelectronicsynthesiser!

THEREARELOTSofwaystomakecodecontrolthingsintherealworld.YouhavealreadycontrolledmovementwithmotorsandcontrolledlightwithLEDs.Inthisadventureyou’regoingtocreatesound!

InAdventures3and4,youdiscoversomenewwaystomakeyourcodemoreefficientwhenyouneedtorepeattheinstructionsmorethanonce.Theforloopisagreattoolforrepeatingsomethingasetnumberoftimes.Whenyoucombineaforloopwithspeciallistsincode—calledarrays—youendupwithapowerfulcodingtool.

AfterlearninghowtoharnessthepowerofarraysandfiguringouthowtogetyourArduinotosingtoyou,you’regoingtoputyournewskillsintopracticebybuildinganaugmentedwindchimethatplaysbothacousticandelectronicsounds.

WhatYouNeedYouneedafewthingsforthefirstpartofthischapter(theelectroniccomponentsareshowninFigure5-1):

AcomputerAnArduinoUnoAUSBcableAbreadboard7jumperwires6LEDs6220ΩresistorsApiezo

Figure5-1Theelectroniccomponentsyouneedforthefirstpartofthisadventure

MakingaListVariablesareusefulwaysofkeepingtrackofinformationlikethenumbersofthepinsonyourArduinoUno.CreatingavariabletostorethenumberofthepintowhichaparticularLEDisconnectedmakesyourcodeeasiertoreadlateron.Whenyoucreateavariablelikethis:intledPin=12;

youcanwritethislater:digitalWrite(ledPin,HIGH);

insteadofhavingtowritethis:digitalWrite(12,HIGH);

Usingthevariablemakesyourcodeeasiertoread.YoumightnotrememberwhatisconnectedtoPin12,butthevariableledPinmakesiteasiertofigureoutwhatthecodeisdoing.

ButwhatifyouwanttokeeptrackofmorethanoneLED?Well,youcouldcreateavariableforeachpin,likethis:intledPin1=3;

intledPin2=4;

intledPin3=5;

intledPin4=6;

intledPin5=7;

intledPin6=8;

Butthatdoesn’tseemveryefficient!Whyshouldyouhavetotypethesamethingoverandoveragainwhen,asweknow,computersaregoodatdoingthesamethingmanytimes.Theremustbeabetterway,right?

Thereis!Computers,includingtheArduino,cancollectinformationinlistscalledarrays.Insteadofhavingtocreateavariableforeachpieceofinformation,youcreateavariablethatisanarray.Wheneveryouwanttorefertooneoftheitemsinthearray,yousimplygivethenumberofthatitem.Figure5-2showsexamplesoftwoarrays.

Anarrayisalistofthesametypeofthingincode.Forexample,anarraycanholdalistofints.

Figure5-2Twoexamplearrays

Theonelittletricktorememberwitharraysisthatthefirstitemisn’tnumber1;it’sactuallynumber0.So,forexample,ifyouwantedtousethefirstiteminthelistcalledledPins,youwouldtype:ledPins[0]

IfyouwanttoturnonanLEDonthepinnumberstoredinthethirditeminthearray,youwouldtype:digitalWrite(ledPins[2],HIGH);

MakingYourIntentionsKnownSo,howdoyoucreateanewarray?Youdon’tjustcreateavariablethatholdsasinglenumber,likeanintorfloat.Theprocessinvolvesmorestepsthanthat.

Afloatisadatatypefornumbersthataren’twholenumbersbutincludeadecimalplacesuchas1.3or-54.089.

Thefirststepistodeclarethenewvariablethatwillholdthearray.Declareisjustafancywordforsomethingyouhavealreadybeendoinginyoursketches.Itmeanscreatinganewvariablebygivingitanameandadatatype.ThefollowinglineofcodedeclaresanewvariablecalledledPinthatcontainsanint:intledPin;

Declaringavariableiswhereyoucreateanewvariablebygivingitanameandadatatypesuchasint.Thevariabledoesnotholdavalueuntilitisgivenitsfirstvalue.

Ifyoualreadyknowwhatvalueyouwanttostoreinthevariablewhenyoucreateit,youcaninstantiateitatthesametime.Thatjustmeansgivingitastartingvalue:intledPin=13;

Instantiatingavariableiswhereyougiveitavalueforthefirsttime.Instantiationcanhappenatthesametimeyoudeclarethevariable,oryoucandoitlater,butthedeclarationalwaysneedstocomefirst.

Youdon’thavetodeclareandinstantiatethevariableatthesametime.;youcandeclareavariableandinstantiateitlateroninyourcode:intledPin;

//somemorecodehappenshere

ledPin=13;

Becarefulifyoudecidenottoinstantiateavariableatthesametimethatyoudeclareit.Youcan’tusethatvariableuntilithasavalue,oryourArduinocodemightnotworkasyouwouldexpect.

TodeclareandcreateanewarrayofsixintegerscalledledList,usethefollowingcode:intledList[6];

Theprecedingcodeisonlyalittledifferentfromwhatyouwouldtypetocreateanewvariablethatholdsanint.AfterthevariablenameledList,thereis[6].The[]meansthatinsteadofasingleint,thevariableisgoingtoholdanarrayofints.The6isthe

numberofintsthearraywillhold.

Nowthatyouhavecreatedthearraybydeclaringit,youcaninstantiateit,andfillitwithvalueslaterinthecode:ledList[0]=3;

ledList[1]=4;

ledList[2]=5;

ledList[3]=6;

ledList[4]=7;

ledList[5]=8;

Declaringanarrayandnotinstantiatingitatthesametimeisusefulifyoudon’tknowwhatvaluesneedtogointothearraywhenyoucreateit.However,ifyoualreadyknowwhatallthevaluesshouldbe,youcaninstantiatethearrayatthesametimeyoudeclareit,asshownhere:intledList[]={3,4,5,6,7,8};

Thevaluestobestoredinthearrayarelistedbetween{and}.The[]nolongerneedsanumberinit,becausethenumberofitemsinthearrayisestablishedbythenumberofitemsin{}.

LoopingThroughanArrayIt’seasytodothesamethingwitheachiteminanarraywithoutcopyingandpastingthesamecodemultipletimes.Youcanuseaforlooptodothis.Asyoumightrememberfromearlieradventures,aforloophasthreepartsthatdeterminehowmanytimesitisrun.Anewvariable,oftennamedi,iscreatedandusedtocountthroughtheloop.Inthefollowingcode,theloopwillrunsixtimes:inti;

for(i=0;i<6;i++){

}

i++indicatesthatthevariableiincreaseseachtimethecomputerrunsthroughtheloop.Insteadofaccessingasingleiteminthearray,suchasledList[3],thevariableicanbeusedtoaccessthenextiteminthelisteachtimethroughtheloop.Here’sanexample:inti;

for(i=0;i<6;i++){

Serial.println(ledList[i]);//printthenextiteminthelist

}

Youcanalsowriteaforloopsothatitmakesachangetoeachiteminthearray:inti;

for(i=0;i<6;i++){

ledList[i]=i+2//add2toeachiteminthearray

}

DIGGINGINTOTHECODE

Thecodesnippeti++isshorthandfori=i+1,butthat’snottheonlyusefulcodesnippet.Ifi++increasesibyadding1toitandsavingthenewnumberini,youmightbeabletoguesswhati--does.That’sright;itsubtracts1fromiandsavesthenewnumberini.

Anotherwaytoincreaseiby1istowritei+=1;similarlyyoucandecreaseiby1bywritingi-=1.Youcanusetheseconventionstoincreaseanddecreaseavariablebyanynumber,sotoincreaseiby3itwouldbei+=3ortodecreaseby7itwouldbei-=7.

PuttingItIntoPracticeThat’senoughtalkingaboutwhathappensincode.It’stimetolightupsomeLEDsandactuallyseewhathappensincode!

Thiscircuitisoneyouhaveseenmanytimesbeforeinotheradventures—anLEDwithacurrentlimitingresistor.Thistime,you’regoingtosetupsixofthemondigitalPins3to8,asshowninFigure5-3:

1. StartbyusingajumperwiretoconnectaGNDontheArduinoUnotoalongrowonthebottomofthebreadboard.Ifyourbreadboardislabelledwithablueorblacklineora–,connectGNDtothatrow.

2. PlacethesixLEDsacrossthebreadboardbyinsertingtheshortlegofeachLEDintothelongrownowconnectedtoGND.Spreadthemoutevenlyacrossthebreadboard.

3. PlacethelonglegofeachLEDintoashortrowthatiseasyforthatLEDtoreach.Itdoesn’tmatterwhichrowsyouuse;theonlyimportantthingisthateachLEDisinitsownshortrow.

4. ConnectonelegofaresistortoeachshortrowthatyoujustinsertedtheLEDinto.Bendthelegsoftheresistorssothattheyreachoverthegapinthemiddleofthebreadboard,andinserttheotherresistorlegintotheshortrowacrossthegap.

5. ConnecteachresistortoanoutputpinontheArduinoUno.UsesixjumperwirestoconnectPins3through8totheresistors.

Figure5-3ThecircuitforanarrayofLEDs

Thefollowingcodeletsyouputintopracticesettingupanarrayofvalues.Here,eachoftheitemsinthearrayisapinnumberthatcontrolsanLED.SothewholearrayofLEDscanbeblinkedinthesamewayyouwouldblinkasingleLED.ThepinMode()issetforeachofthepins,andeachpinissettoHIGHandthenLOW://pinsforleds

intledList[]={

3,4,5,6,7,8};

//numberofpins

intnumPins=6;

voidsetup(){

inti;

for(i=0;i<numPins;i++){

//setpinstoOUTPUT

pinMode(ledList[i],OUTPUT);

}

}

voidloop(){

//blinktheLEDsonebyone

inti;

for(i=0;i<numPins;i++){

//turnontheled

digitalWrite(ledList[i],HIGH);

delay(500);

//turnofftheled

digitalWrite(ledList[i],LOW);

delay(500);

}

}

Whathappensifyouchangetheforloopintheloop()functiontofor(i=numPins-1;i>=0;i--)?

DIGGINGINTOTHECODE

YoursixLEDsarenowblinkingonandoff,onebyone,buthowisthecodemakingthathappen?Let’sstartatthetopofthesketch.Thereyouseethevariablesbeingused.ThefirstisanarrayledListthatholdsallthepinnumbersfortheLEDs,andthesecondisanint,numPins,thatstoresthetotalnumberofLEDpins:

//pinsforleds

intledList[]={

3,4,5,6,7,8};

//numberofpins

intnumPins=6;

Goingoninthecode,youcometoyourfirstforloopofthesketchinsetup().TheforloopisusedtosetthepinmodeofeachoftheLEDpinstoOUTPUT.Thevariableiisusedtoiteratethrougheachiteminthearray:

inti;

for(i=0;i<numPins;i++){

//setpinstoOUTPUT

pinMode(ledList[i],OUTPUT);

}

Thesecondforloopofthesketchisinloop().Thevariableiisusedagaintoiteratethroughthearray.Thistime,insteadofsettingthepinmodeforeachpin,thepinisturnedonbybeingsettoHIGH.TheArduinoUnowaitsfor500mswhendelay(500)iscalled,andthenthepinisturnedoffbybeingsettoLOW.TheArduinoUnoispausedfor500msagainbeforegoingontothenextpininthearray.

//blinktheLEDsonebyone

inti;

for(i=0;i<numPins;i++){

//turnontheled

digitalWrite(ledList[i],HIGH);

delay(500);

//turnofftheled

digitalWrite(ledList[i],LOW);

delay(500);

}

Becausetheforloopisinsideloop(),itgetscontinuouslyrununtiltheArduinoUnoisnolongerpowered.

MakingNoiseIt’snotunusualforcomputerstomakesounds.Youprobablylistentomusicstoredonamusicplayerorphone(whicharetypesofcomputers)allthetime,butyoumightnothavegivenmuchthoughttohowthecomputerphysicallycreatesthesoundyouhear.

Soundisjustvibrations(usuallyvibrationsintheair)thatourearscandetect.Thespeedatwhichsomethingvibratesdetermineswhetheritsoundsloworhigh.ThevibrationsaremeasuredinHertz(Hz),whichisequivalenttocyclespersecond.Humanscanheararound20Hzto20,000Hz,thoughaswegetolderwetendtonothearhighfrequenciesaswellaswedowhenweareyounger.Figure5-4illustrateshowsoundismade.

Figure5-4Howsoundismade

So,howdoesacomputergetairtovibrate?AcomputerorArduinoUnocanoutputachangingvoltagethatalternatesbetweenpositiveandnegative.Aloudspeakertakesthatchangingvoltageandturnsitintovibrations.Onetypeofloudspeakerusesapiezoelement.Thisusuallylookslikeagolddiscwithtwowirescomingfromit,althoughitissometimesenclosedinplastic.

Apiezoisacrystalthatexpandsandshrinkswhenelectricityisrunthroughit.Italsogenerateselectricitywhenitissqueezedorbent.

Nowthatyouknowalittlebitabouthowcomputersgeneratesound,youcanmakeyourArduinoproducesometones.YouknowthattheArduinooutputs0and5VbecauseyouhaveuseddigitalWrite()tosetapintoLOW(0V)andHIGH(5V).MakinganArduinoboardoutputavoltagebetween0and5Visactuallyatrickythingtodo.LuckilytheArduinolibraryhasabuilt-insetoffunctionsthatdoesthisandgeneratessoundwithoutyouneedingtoknowthedetails.Ofcourse,ifyouwouldliketoknowmoreabouthowsoundisgenerated,youcanreadmoreintheArduinodocumentationathttp://arduino.cc/en/Reference/Tone.

WiringtheCircuitApiezohastwowiresattachedtoit.TheblackwireconnectstoGNDontheArduinoboardandtheredwireconnectstothepinthattheaudioplaysfrom.ConnecttheblackwiretoGNDandtheredwiretoPin8now,asshowninFigure5-5.

Figure5-5Thecircuitforausingapiezoasaspeaker

WritingtheCodeThemainfunctionforcreatingsoundistone().Itcanbeusedintwoways.Thefirstistogivethreearguments:thepinthatthesoundshouldplayfrom;thefrequencyofthesound;andhowlongthesoundshouldplay.Here’sanexample://playonPin8atoneof750Hzfor1000ms(1s)

tone(8,750,1000);

delay(1000);

Noticethatrightafterthetone()functionthereisadelay()function.Evenifthetone()functionistoldhowlongtoplayasound,theArduinoboardstillneedstobetoldtowaitforthesoundtofinishplayingbeforetone()iscalledagain.Thedelay()functionspecifieshowlongthatwaitshouldbe.

Theotherwaytousethetone()functionistogiveitonlytwoarguments:thepinthatthesoundshouldplayfrom;andthefrequencyofthesound.Thesoundstartsplayingwhenthefunctioniscalled,anditdoesn’tstopuntilthefunctionnoTone()iscalled,asinthefollowingcode://playonPin8atoneof750Hz

tone(8,750);

//othercodecanhappenhere

//stopthetone

noTone(8);

Thefunctionstone()andnoTone()canbeusedinsetup()ifyouwantsoundtoplayonlyoncewhentheArduinoisfirstpowered,orintheloop()ifthesoundshouldplayrepeatedly.

AsyouhavealreadyconnectedthepiezototheArduinoboard,allthatremainsisforyoutouploadthefollowingcode:intpiezoPin=8;

voidsetup(){

//play3toneswhentheboardfirststarts

tone(piezoPin,523,200);

//delayisslightlylongerthantone

//sothatthereissilenceinbetweenthesounds

delay(210);

tone(piezoPin,784,200);

delay(210);

tone(piezoPin,1047,250);

delay(260);

}

voidloop(){

//play5moretones

tone(piezoPin,523,200);

delay(210);

tone(piezoPin,587,200);

delay(210);

tone(piezoPin,659,200);

delay(210);

tone(piezoPin,698,200);

delay(210);

tone(piezoPin,784,200);

//wait5secondsbeforestartingtheloopover

delay(5000);

}

WhentheArduinofirstrunsthecode,youshouldhearthreenotesmagicallyringingout.Thethreenotesshouldthenplayinarepeatedpattern(thatgoesonandonandonandon…).

DIGGINGINTOTHECODE

Sowhatexactlyishappeninginthesketchyoujustuploaded?Theformatofthesketchissimilartotheothersyouhaveworkedwith:Variablesarecreatedatthetop,anythingthathappensonlyonceisdoneinsetup(),andeverythingelsethathappensrepeatedlyisdoneinloop().

Thissketchonlyhasonevariable:

intpiezoPin=8;

Thesetup()inprevioussketcheshasbeenusedtosetpinmodes.Thatdoesn’tneedtohappeninthissketchbecausetheonlypinbeingusedisoutputtingsoundusingtone().Instead,youusetone()todemonstratethedifferencebetweensetup()andloop().Thesetup()playsthreetonesbeforetheloop()playsfivetones.Thetonesinsetup()onlyplayonce,whentheArduinoUnoisfirststarted,butthefivetoneskeepplayingandplayinguntilyouremovepowerfromtheboard.

Thesetup()onlycallstwofunctions.Thefirstistone(),whichtellstheArduinoUnowhatfrequencytoplayonwhatpinandforhowlong.Thendelay()iscalledtomaketheArduinoUnowaitforthetone()tofinishplayingbeforecontinuingontothenextlineofcode.

//play3toneswhentheboardfirststarts

tone(piezoPin,523,200);

//delayisslightlylongerthantone

//sothatthereissilenceinbetweenthesounds

delay(210);

tone(piezoPin,784,200);

delay(210);

tone(piezoPin,1047,250);

delay(260);

Theloop()isjustlikesetup()exceptitplaysfivetonesinsteadof

three:

//play5moretones

tone(piezoPin,523,200);

delay(210);

tone(piezoPin,587,200);

delay(210);

tone(piezoPin,659,200);

delay(210);

tone(piezoPin,698,200);

delay(210);

tone(piezoPin,784,200);

//wait5secondsbeforestartingtheloopover

delay(5000);

Ifyouknowhowtoreadsheetmusic,openFile ⇒ Examples ⇒ 02.Digital ⇒ toneMelody.Youcansee

thattherearetwotabsintheArduinoIDE:onelabelledtoneMelodyandanotherlabelledpitches.h.

Thetabpitches.hisalistofvalueslikethis:

#defineNOTE_B031

JustpayattentiontoNOTE_B0and31.ThefirstisthemusicalnoteBandthenumber(31,inthisexample)isthefrequencyforthatnote.Thenumbernexttothenote(likethe0inB0)istheoctave.Youcanusethesenumberstohelpyouwritemusicalmelodies.

CHALLENGE

Thefollowingcodeusesanarraytoplaythesamesequenceofsounds.CreateanewsketchwiththefollowingcodeanduploadittoyourArduinoUno.Trychangingthearraysoitplaysthepitchesinreverse(hightolowinsteadoflowtohigh):

intpiezoPin=8;

intpitches[]={

523,587,659,698,784};

intnumPitches=5;

voidsetup(){

//play3toneswhentheboardfirststarts

tone(piezoPin,523,200);

//delayisslightlylongerthantone

//sothatthereissilenceinbetweenthesounds

delay(210);

tone(piezoPin,784,200);

delay(210);

tone(piezoPin,1047,250);

delay(260);

}

voidloop(){

//play5moretones

inti;

for(i=0;i<numPitches;i++){

tone(piezoPin,pitches[i],200);

delay(210);

}

//wait5secondsbeforestartingtheloopover

delay(5000);

}

BuildinganAugmentedWindChimeAnaugmentedmusicalinstrumentiswhatcanbecalleda“normal”musicalinstrument—suchasatrumpetorpiano—thathaselectronicsaddedtoit.Theelectronicsletthemusicianuseacomputerormicrocontrollertoaddtothesoundthattheinstrumentnaturallymakes.

Asyouhavejustdiscovered,theArduinohasasetoffunctionsthatcangeneratesound.YouknowthattheArduinocanalsoreadininformationfromitspins,soyoucancombinereadingfrompinstotriggerdifferentsounds.Tocompletethisadventureinsound,you’regoingtoaugmentawindchime(seeFigure5-6)sothatitdoesn’tjustmaketheusualsoundswhenit’sbuffetedbythewindbutalsoplaystonesproducedbytheArduino!

Figure5-6Anaugmentedwindchime

Youcanwatchavideoonhowtomakeyouraugmentedwindchimeonthecompanionsiteatwww.wiley.com/go/adventuresinarduino.

Therearelotsofaugmentedinstrumentsthatyoucanreadaboutandlearnfrom!Herearesomeofmyfavourites,butyoucandosomeresearchonlineandfindevenmore:

MagneticResonancePiano:www.eecs.qmul.ac.uk/~andrewm/mrp.htmlDigiDidgeridoo:http://createdigitalmusic.com/2009/12/digi-didgeridoo-augmented-wireless-digital-instrument-with-aboriginal-

roots

AugmentedBeatboxing:www.cs4fn.org/music/beatboxing.php

WhatYouNeedYouneedthefollowingitemstobuildyouraugmentedwindchime.Figure5-7showstheelectroniccomponentsyouneed.

AcomputerAnArduinoUnoAUSBcableAbreadboard12jumperwires5tactilepushbuttonsAstripof5headerpinsA9VbatteryA9Vbattery-to-DCbarreljackconnectorSomethinwireSmallpieceofsolidcorewireSomestring,ribbonoryarn10beads(plasticorglasslargeenoughtopassstringorribbon)6washersorotherconductiveobjecttoactasthechimesSomestiffcardboardorplastictouseasthebaseMaskingtapeAsolderingironSomesolderScissorsorautilityknifeApencilorholepunchAmultimeterwithcontinuitytest

Figure5-7Theelectroniccomponentsyouneedtomakethewindchime

UnderstandingtheCircuitThere’snottoomuchtothecircuitforthewindchime;itcombinesswitcheswithapiezospeaker.Thefunpartisthatthefinalcircuitusesmaterialsthatyoudon’tnormallyseeinelectronics.Beforeexperimentingwithnewmaterials,it’sagoodideatobuildaprototypeofthecircuitonabreadboardtomakesureitworksasyouexpectitto.

Figure5-8showsthecircuitschematicforthewindchime.Itlooksverydifferenttothefinishedwindchime!Thechimesactasswitches,eventhoughtheydon’tlooklikenormalswitches.

Figure5-8Circuitschematicfortheaugmentedwindchime

PrototypingonaBreadboardThecircuitconsistsoffiveswitchesondigitalpinsandonepiezoonanotherdigitalpin.Becauseyoulearnedhowtousetheinternalpull-upresistorintheArduinoUnoinAdventure3insteadofneedingtoaddaresistortotheswitchcircuits,therearen’tthatmanycomponents.

BuildthecircuitshowninFigure5-9:

1. Placefivetactilepushbuttonsacrossthegapinthemiddleofthebreadboardsothattwoofthelegsareinsertedinshortrowsabovethegapandtheothertwolegsareinsertedinrowsbelowthegap.

2. UseajumperwiretoconnectaGNDpinontheArduinoUnotoalongrowalongthebottomofthebreadboard.Ifthebreadboardislabelledwithablackorbluelineora–,usethatrow.

3. Usefivejumperwirestoconnectthebottom-rightlegofeachpushbuttontothelongrowconnectedtoGND.

4. Usefivejumperwirestoconnecttheupper-leftlegofeachpushbuttontoPins3through7ontheArduinoUno.

5. Connecttheredwireofthepiezotoanyemptyshortrowonthebreadboard.UseajumperwiretoconnectthatshortrowwithPin8ontheArduinoUno.

6. ConnecttheblackwireofthepiezotothelongrowconnectedtoGND.

Figure5-9Breadboardprototypecircuit

ThewindchimecircuitisalittledifferentfromthecircuitinAdventure3thatusedaswitch.Insteadofpushbuttonswitches,you’reusingconductivemetallicitems(suchaswashersoranythingelseyouchoose)connectedtowiresdanglingfromthewindchime’sbase.Eachoftheseconductiveitemsisconnectedtoadigitalpin.Asixthconductiveitemthat’sconnectedtoGNDhangsinthemiddle.Whenthewindcausesthemiddleconductivechimetocomeintocontactwithoneofthechimesconnectedtoapin,itiselectricallythesameaspushingthebuttononthecombinationsafeinAdventure3.

WritingtheCodeLaunchtheArduinoIDEandopenanewsketch.Typethefollowingcodeinyoursketch:intchimes[]={

3,4,5,6,7};//arrayofpinsforchimes

intnumChimes=5;//totalnumberofchimes

intpiezoPin=8;//pinforpiezo

voidsetup(){

inti;

//setpinModeonallthechimespins

for(i=0;i<numChimes;i++){

pinMode(chimes[i],INPUT_PULLUP);

}

}

voidloop(){

inti;

for(i=0;i<numChimes;i++){

//readinvalueonpin

intvalue=digitalRead(chimes[i]);

//ifLOW(meaningithasconnectedtoground

if(value==LOW){

//playthesound

tone(piezoPin,(100*i)+200,30);

delay(1);

}

}

}

UploadthesketchtoyourArduinoUnoconnectedtothetactilepushbuttonsandpiezocircuityoujustbuilt.Youshouldhearadifferentpitchplayedwheneachbuttonispressed.

Ofcourse,youcanchangewhatisplayedwheneachchimeistriggered.Comeupwithyourownmusicalalgorithm!

DIGGINGINTOTHECODE

Themainpartsofthesketchuseanarray,aforlooptoiteratethroughthatarray,andthetone()function.Thearraychimes[]storeseachpinnumberthatisconnectedtotheconductivechimes(orprototypedwithapushbutton).

intchimes[]={

3,4,5,6,7};//arrayofpinsforchimes

intnumChimes=5;//totalnumberofchimes

intpiezoPin=8;//pinforpiezo

Thesetup()thensetsthepinmodesforeachofthepinsconnectedtothepushbuttonsorchimes.Becausetheyareinputsthatusetheinternalpull-upresistorsintheArduinoUno,youusetheargumentINPUT_PULLUP.

inti;

//setpinModeonallthechimespins

for(i=0;i<numChimes;i++){

pinMode(chimes[i],INPUT_PULLUP);

}

Theforloopintheloop()checksthevalueofeachpin.WhenachimeconnectstoGND,atone()isplayed.Becauseyou’veusedaninternalpull-upresistor,youknowthatthevalueofapushbuttonorchimeisHIGHwhenit’snotconnectedtoground,andthenthevaluechangestoLOWwhenitisconnectedtoground.Thefrequencyofthetone()isdeterminedbywhichchimetriggeredthesound.

inti;

for(i=0;i<numChimes;i++){

//readinvalueonpin

intvalue=digitalRead(chimes[i]);

//ifLOW(meaningithasconnectedtoground

if(value==LOW){

//playthesound

tone(piezoPin,(100*i)+200,30);

delay(1);

}

}

MakingtheWindChimeNowthatyouknowthatyoursketchisworkingcorrectlyandyouhavebuiltatestcircuitonyourbreadboard,youarereadytomakeyourwindchime.Thewindchimeisconstructedfromabasefromwhichhangsixchimes—fiveouterchimesandagroundedinnerchime.Youcanmakethewindchimefromanymaterialsyoulike,butit’simportantthatthechimesareconductiveandthattheyareelectricallyconnectedtotheArduinoUno.Visitahardwarestoreandlookthroughallthesmallmetalfasteningstochoosewhatyouwanttouseaschimes.Washerscomeinmanydifferentsizes,butyoumightpreferhexagonalnutsovercircularwashers.

MakingtheBaseYoucanmakethebasefromanythingthatisstrongenoughtosupportyourchimesandcanalsoholdanArduinoUnoandbattery.Stiffcardboardorplasticaregoodoptions.

First,cutacirclefromthebasematerialthat’sapproximately6inchesindiameter.Pokesixsmallholesinit;thestringsandwirespassthroughtheseholes.Fiveoftheholesshouldbeevenlydistributedaroundtheoutsideofthebase,andthesixthholeshouldbeinthecenter.

Pokefourmoreholesaroundtheedgesofthebase.Theseareforthestringstohangthechime.

MakingtheChimesWhenyouchoosewhatmaterialtousetomakethechimes,youneedtoremembertwoimportantcharacteristics:youneedtobeabletosolderwirestoitanditmustconductelectricity.Totestifyoucansoldertoit,justtrytodoit!Whatevermaterialyouhavechosen,itwillprobablytakeafewmoresecondstogethotenoughtosolderthansomethingsmalllikeawire,sobepatient.

Onlysolderwhenanadultisnearbytohelp!Ittakesalotofheatfromtheirontogetyourchimehotenoughtomeltsolder.Italsotakesalongertimetocooldownafteryou’vesolderedyourwiretoit.Beverycarefulandwaitatleast5minutesbeforepickingupsomethingyou’vesoldered.

Tocheckwhetherthematerialconductselectricity,youneedamultimeter.Amultimetermeasuresmultiplethings(soit’saprettygoodname),includingvoltageandresistance.Youneedameterthatalsomeasurescontinuity.Continuityindicateswhethercurrentcanflowbetweenthetwoprobesattachedtothemeter,whichindicatesconductivity.Notallmultimetershaveacontinuitytest,sopayattentiontothelistedfeaturesofthemultimeterbeforeyoubuyit.

Testyourpotentialchimebytouchingitintwodifferentspotsonthechimewiththeprobes(seeFigure5-10).Ifthemultimeterbeeps,yourmaterialisconductive.Ifit

doesn’t,youshouldfindsomethingelsetouse.

Figure5-10Conductivitytest

Ifyouareusingverythinwirethandoesn’thaveaplasticsleevearoundit,itmaystillhaveathincoatingofinsulationonit.Ifyouhaveproblemssolderingitoritfailsacontinuitytest,youcanscrapeofftheinsulatingcoatingwithsomesandpaperoranailfile.

Afteryouhavechosenyourmaterialforyourchimes,solderawiretoeachofthem.ThewireshouldbelongenoughtoreachfromwhereyouwantthechimetohangthroughthebaseandtotheArduinoUno.Wrapthewireseveraltimesaroundyourchime(seeFigure5-11)andmakesureyouhaveastrongelectricalconnectionandthensolderittothechime.

Figure5-11Achime

Asyet,thewireistooweaktosupportthechimebyitself.Chandeliersareheldupbyastrongchainwithawirethatrunsalongittolightupthebulbs.Inthesameway,togiveyourwindchimeextrasupport,thenextsectionwillshowyouhowtousestringorribbontohangthechime.

AttachingtheChimesThemostimportantthingtorememberisthatthestringorribbonshouldbearalltheweightofthechime;thewireisjusttheretoconductthesignalfromtheArduinotothechime.Thewireshouldnotbearanyweight.

TieapieceofstringorribbonaroundthechimeasshowninFigure5-12.Bringthewireandribbonupthroughtheholetogetherandthenthreadabeadontothestringorribbon—notthewire.Tieaknotinthestringorribbontokeepthebeadinplaceandkeepthechimefrompullingthestringbackthroughthebase(seeFigure5-12).

Dothiswithallsixchimes.

FIGURE5-12Achimeattachedtothebase

ConnectingtheElectronicsYouarealmostfinished!Nowtocompletethefinalfewsteps:

1. Solderasmallsectionofsolid-corewiretothechimehangingfromthecenter.PlugthatwireintoGNDontheArduinoboard.

2. TapetheArduinoboardandpiezotothetopofthebase.ConnecttheblackwireofthepiezotoaGNDpinontheArduinoboardandconnecttheredwiretoPin8.

3. Soldereachofthewiresfromthefiveremainingchimestoapinonthesectionofheaderpins.Thisissometrickysoldering,sojusttakeyourtime.Placetheheaderpinsinabreadboardtoholdthepinsupright.Heatupaheaderpinwiththesolderingironandcoatitinsolder.Thenheatuptheendofthewireandcoatitinsolder.Placethewiresoittouchestheheaderpinandheatupbothagainsothatthesoldercoatingthemmeltsandconnectsthemtogether.Repeatthisprocessfortheremainingpins.

4. PushtheheaderpinsintoPins3through7.5. ConnectthebatterytotheArduinoboardusingthebatteryholder(seeFigure5-13)

andattachthebatterytothebaseusingtape.

Figure5-13Topofbase

Cuttwomorepiecesofstringabout24”long.Thesewillhangyourwindchime.Foldthemeachinhalfandthreadeachendofthestringsthroughoneofthefourholesonthebase.Theendsshouldstickoutfromthebottomofthebase.Tieabeadontoeachstringtokeepthestringfrompullingbackthroughthebase.Hangupyourwindchime,andenjoyyouraugmentedsounds!

FurtherAdventureswithSoundYouarenowasoundsavant!Youcancontrolsoundalongwithlightandmotionfromyourcircuitandcodeknowledge.Plus,younowknowthatyoudon’thavetogotoaspecialshoptobuymaterialsforyourcircuits.Youcantestwhethersomethingconductselectricityandstartusingeverydayhouseholditemsinyourcircuits.

Ifyou’dliketoreadmoreabouthowtousetone(),visittheArduinodocumentationathttp://arduino.cc/en/reference/tone.

Youmightwanttocheckoutsomeoftheseotherexamplesandtutorialsonline:

http://arduino.cc/en/Tutorial/Tone

http://arduino.cc/en/Tutorial/Tone2

http://arduino.cc/en/Tutorial/Tone3

http://arduino.cc/en/Tutorial/Tone4

http://itp.nyu.edu/physcomp/labs/labs-arduino-digital-and-analog/tone-

output-using-an-arduino/

https://learn.adafruit.com/adafruit-arduino-lesson-10-making-sounds

IfyouarecuriousaboutexactlyhowtheArduinomakessound,checkouttheWikipediapageonPulseWidthModulation(PWM)athttp://en.wikipedia.org/wiki/Pulse-width_modulation.Adventure6showsyouhowPWMisusedtocontrollightinsteadofsound.

ArduinoCommandQuickReferenceTable

Command Description

[]Indicatesthatthevariableisanarrayofvariablesratherthanasinglevariable.Seealsohttp://arduino.cc/en/Reference/Array.

tonePlaysasoundwithagivenfrequency.Ifadurationisgivenaswell,thesoundplaysonlyforthatlengthoftime;otherwise,thesoundplaysuntilnoToneiscalled.Seealsohttp://arduino.cc/en/Reference/Tone.

noTone Stopsthetonefromplaying.Seealsohttp://arduino.cc/en/Reference/NoTone.

AchievementUnlocked:Inspirationalengineerofsound!

IntheNextAdventureInthenextadventure,youuseevenmorematerialsthatyouwouldn’texpectinanelectricalcircuit.Youalsofindouthowtocontrolacolour-changingLED!

IT’STIMETOpushtheboundariesofyourArduino!InpreviousadventuresyouusedDigitalandAnalogPinsonyourArduinoUno,butwhat’sthedifferencebetweenadigitalandanaloguesignal?YouhaveoutputonaDigitalPininAdventures1through3,havereadinfromaDigitalPininAdventures2and5,andreadinfromanAnalogPininAdventure2,butwhataboutoutputtinganaloguesignals?Well,thatcomesnext.Butthenwhat?Afteryou’vetackledoutputtinganaloguesignals,isthatit?IsthattheendofArduinocoding?Notatall!

YoucanpushyourArduinoevenfurtherbyusinglibraries.Thisallowsyoueasilytoincorporatecleverfunctions,whichhavebeenwrittenbyotherpeople,intoyoursketches.Inthisadventureyouwillusealibrarythatletsyouturn(almost)anythingyoulikeintoatouchsensor.Youarethengoingtobuildamagicalcrystalballthatglowswhenyouwaveyourhandsoverit.

WhatYouNeedYouneedthefollowingitemsforthefirstpartofthisadventure.TheelectroniccomponentsareshowninFigure6-1.

AcomputerAnArduinoUnoAUSBcableAbreadboard4jumperwires1LED1RGBcommoncathodeLED3220Ωresistors110MΩresistor

Figure6-1Theelectroniccomponentsyouneedforthefirstpartofthisadventure

AnalogueOutIfyouhavecompletedAdventures1,2or4,youknowthatdigitalWrite()candotwothings:output5VwhensettoHIGHoroutput0VwhensettoLOW.YouthenusedigitalRead()toreadinwhetherapinisconnectedto5Vor0V.YoucancheckoutAdventure3ifyouneedarefresheronusingdigitalRead()toreadfromapushbutton.

YoualsoknowfromAdventures2and3thatifyouwanttomeasureavoltageonapinthatisbetween0Vand5V,youneedtouseanalogRead().Itreturnsanumberbetween0and1023thatcorrespondstotheinputvoltage.Soitstandstoreasonthatifyouwanttooutputavoltagebetween0Vand5V,thereisprobablyafunctioncalledanalogWrite()thatwouldletyoudothat.That’sabsolutelycorrect!

Butfirst,whatexactlyisthedifferencebetweenananalogueanddigitalsignal?Adigitalsignalisanelectricalsignalthatcanonlybeoneoftwothings—eitheronoroff.Whenrepresentedinelectricity,it’seither5V(on)or0V(off).Whenrepresentedincode,it’seitherHIGH(on)orLOW(off).

Adigitalsignalisasignalthatisonlyeitheronoroff,HIGHorLOW.OntheArduinoUno,aHIGHsignalis5VandaLOWsignalisground.

Ananaloguesignalisasignalthatcanbevaluesbetweenonandoff.Whenrepresentedinelectricity,itcanbeanyvoltagebetween0Vand5V.Whenrepresentedincode,itcanbeanynumberbetween0and1023.Figure6-2furtherillustratesthedifferencebetweenanalogueanddigitalsignals.

AnanaloguesignalisasignalthatvariesbetweenLOWandHIGH.OntheArduinoUno,ananaloguesignalcanbemeasuredasanumberbetween0forgroundand1023for5V.Ananaloguesignalcanbeoutputasavaluebetween0for0Vand255for5V.

Figure6-2Analogueanddigitalsignals

YoucanoutputadigitalsignalusingdigitalWrite()andcanuseanyDigitalPinontheboard.YoucanalsoreadinadigitalsignalusingdigitalRead()usinganyDigitalPinandreadinananaloguesignalusinganyAnalogPin.Tooutputananaloguesignal,youuseanalogWrite(),butyoucanonlyusespecialDigitalPins.OutputtingavaluebetweenHIGHandLOWistrickierforamicrocontrollerthanoutputtingadigitalsignal,sothereareonlysomeofthepinscandothat.ThesearenicelymarkedonyourArduinoboardwiththe~symbol.OntheArduinoUno,thesearePins3,5,6,10and11(seeFigure6-3).

Figure6-3ThepinsthatsupportanalogWrite()

TheotherimportantthingtoknowisthatnotallArduinopinscanuseanalogWrite().

ReadingandwritingHIGHandLOWtoandfromapinissuper-easyforamicrocontrollerliketheArduinoUnotodo.AlltheinputandoutputpinsontheArduinoboardcandothis—andareverygoodatit.Youcanevenuseanalogpinstoinputoroutputadigitalsignalwhenyouhaverunoutofavailabledigitalpins.ReadinginoroutputtingavoltagethatisbetweenHIGHandLOWishardertodoandrequiressomespecialfunctionalityinthemicrocontroller.ThisiswhyanalogRead()onlyworksonA0throughA5.AndanalogWrite()onlyworksonpinsmarkedwitha~.

JustlikedigitalWrite(),analogWrite()takestwoarguments.Thefirstargumentdefineswhichpinshouldbeusedandtheseconddetermineswhatvoltageshouldbeoutput.Thissecondargumentisalittledifferentfromotherarguments.Youdon’tuseHIGHorLOW;insteadyouuseanumberbetween0and255,with0usedfor0Vand255for5V.Thefollowingexamplecode,outputsasignalonPin6thatisroughlyonethirdof5V,sosetthesecondargumentto83:analogWrite(6,83);

Ifyouwantedtooutputalmostthemaximum(5V),youwoulduseanumberjustunder255:analogWrite(6,249);

FadinganLEDWhywouldyouwanttooutputavoltagebetween0Vand5V?Therearelotsofreasons,butonecommonuseistosmoothlyfadeanLEDonandoff.

StarttheArduinoIDEandopenFile⇒Examples⇒03.Analog⇒Fading.BuildanLEDcircuitwithacurrentlimitingresistoronPin9(seeFigure6-4):

1. UseajumperwiretoconnectaGNDpinontheArduinoUnotoalongrowalongthebottomofthebreadboard.Ifthebreadboardislabelledwithablackorbluelineor–,connectthepintothatrow.

2. InserttheshortlegoftheLEDintotherownowconnectedtoaGNDpin.3. InsertthelonglegoftheLEDintoanynearbyshortrow.Insertonelegoftheresistor

intothesameshortrow.4. Inserttheotherresistorlegintoanyothershortrow.Useajumperwiretoconnect

thatshortrowtoPin9ontheArduinoUno.

Uploadtheexampleandseewhathappens.YoushouldseetheLEDfadeonandoff.

Figure6-4LEDcircuitforfadinganLED

ThisexamplecombinesanalogWrite()withtheforloopyouhavealreadybeenusinginAdventures3through5.ThefirstforloopslowlyincreasesthevoltageoutputtotheLED://fadeinfrommintomaxinincrementsof5points:

for(intfadeValue=0;fadeValue<=255;fadeValue+=5){

//setsthevalue(rangefrom0to255):

analogWrite(ledPin,fadeValue);

//waitfor30millisecondstoseethedimmingeffect

delay(30);

}

Thesecondforloopdoestheopposite,anddecreasesthevoltage://fadeoutfrommaxtomininincrementsof5points:

for(intfadeValue=255;fadeValue>=0;fadeValue-=5){

//setsthevalue(rangefrom0to255):

analogWrite(ledPin,fadeValue);

//waitfor30millisecondstoseethedimmingeffect

delay(30);

}

CHALLENGE

IncreasethespeedatwhichtheLEDfadesonandoffbyadjustingthedelay()time.NowtryincreasingthefadingspeedbychangingfadeValue.

DIGGINGINTOTHECODE

UsingtheanalogWrite()functionactuallyrequiresalittlebitofatrick,becauseitdoesn’treallyoutputasteadyvoltagesomewherebetween0Vand5V.Infact,itusespulsewidthmodulation(PWM).YoumighthavenoticedthatitsaysPWMonyourArduinoboardnexttothe~symbol.PWMoutputsasignalthatswitchesbackandforthbetweenonandoffatdifferentspeeds.ThishappenssofastthatwhenyoulightupanLEDusingPWM,youreyesdon’tseetheswitchingbackandforth.Insteadtheyseesomethinginbetween,likeanLEDatonlyhalfpower.

Pulsewidthmodulation(PWM)ishowtheArduinoboardgeneratesanoutputsignalbetween0Vand5V.ThesignalswitchesquicklybetweenLOWandHIGHandtheresultingoutputvoltageisbetweenthetwovoltages.

Figure6-5showsthreeexamplePWMsignals.Thetoponeisasignalthatismostlyoff,sotheLEDappearsonlydimlyon.Themiddlesignalisonhalfthetimeandoffhalfthetime,sotheLEDappearsroughlyhalfasbrightasanLEDsettoHIGH.Thebottomsignalisonalmostallthetime,sotheLEDappearsalmostasbrightasonethatissettoHIGH.

Figure6-5PulsewidthmodulationexamplesTheratioofhowlongthesignalisoutputtoHIGHversusLOWdetermineshowbrighttheLEDappears.Thisratioiscalledthedutycycle.ThemoretimethesignalisHIGH,thehigherthevoltageappearstobeandthebrightertheLEDseemstoshine.

ThedutycycleistheratiooftimeasignalisHIGHversusLOWinagivencycle.InPWM,thehigherthedutycycle,thehighertheoutputvoltage.

MixingLightTherearemanydifferentkindsofLED,andtheycomeinallshapesandsizes.Thekindyou’veusedinpreviousadventuresiscalledthrough-holeLEDs—thatjustmeanstheyhavelegsandifyouwanttoattachthemtoacircuitboardtheboardhastohaveholesforthelegstogothrough.

LEDsalsocomeinmanydifferentcolours.Red,yellowandgreenarethemostcommon,butyoucanbuyothercolourssuchasblueandorange.TherearealsoLEDsthatarereallythreeLEDsputintowhatlookslikeoneLED.ThesearecalledRGBLEDs,whichstandsforred–green–blueLEDs.

AnRGBLED(red–green–bluelight-emittingdiode)isasingleLEDwithfourlegsthatcontainsthreelights:onered,onegreenandoneblue.Thethreelightsshareeitheracommonanodeoracommoncathode.

TherearetwokindsofRGBLED,andbothofthemhavefourlegs(seeFigure6-6).Threeofthelegsareforthecolours(red,greenandblue).Thefourthlegisasharedleg,eitherasharedpositiveleg(ananode)orasharednegativeleg(acathode).Forbothtypes,youneedthreecurrentlimitingresistors,asyouwouldwiththreeseparateLEDs.

Figure6-6RGBLEDs

Ananodeisthepositivelegofadirectionalcomponent,suchasthelonglegofanLED.

Acathodeisthenegativelegofadirectionalcomponent,suchastheshortlegofanLED.

ThebigdifferencebetweenthetwokindsofRGBLEDisthatthecommonanodeLEDcircuitsharesacommonpowersource,suchas5V,andthecommoncathodeLEDsharesacommonground.It’sabiteasiertothinkabouthowelectricityflowswithacommoncathodeRGBLED,sothat’stheonewe’lluse.

WiringtheCircuitThelongestlegoftheLEDisthecathode—thelegthatgoestoground.Theotherthreelegsareconnectedtothered,greenandbluelightswithintheLED.Tohavethebestcontroloverthelights,usethreeArduinopinsthatcanuseanalogWrite().Pins9,10and11aregoodchoices.BuildthecircuitshowninFigure6-7:

1. TheonlyfiddlypartwhenworkingwithRGBLEDsisfiguringoutwhichlegcontrolswhichcolour.ThebestwaytodeterminethisistoconnecteachLEDlegindividuallyto5Vandseewhatcolourlightsup.Remembertousethecurrentlimitingresistor;don’tdirectlyconnect5VtotheLED.

2. UseajumperwiretoconnectaGNDpinontheArduinoUnotoalongrowalongthebottomofthebreadboard.Ifthebreadboardislabelledwithablackorbluelineor–,connectthepintothatrow.

3. PlacetheRGBLEDinthebreadboardsothateachlegisinitsownshortrow.UseajumperwiretoconnectthelongestlegoftheLEDtothelongrowconnectedtotheGNDpin.

4. Insertonelegofa220ΩresistorintothesamerowaseachofthecolourlegsoftheLED.Bendtheresistoroverthegapinthemiddleoftheboard,andinsertthelegofeachLEDintoitsownshortrow.

5. FindtheredlegandconnecttheresistornowconnectedtoittoPin9withajumperwire;repeattoconnecttheresistorconnectedtothegreenlegtoPin10;andtheresistorconnectedthebluelegtoPin11.

Figure6-7CircuitconnectinganRGBLEDtoanArduinoboard

WritingtheCodeThecodeforcontrollinganRGBLEDlooksjustlikecodethatcontrolsthreeLEDs.CreateanewsketchintheArduinoIDEandwritethefollowingcode.

Youcandownloadallthecodeinthisbookthatisn’tfromtheexamplesthatcomewiththeArduinoIDE.Youcanfinditonthecompanionsiteatwww.wiley.com/go/adventuresinarduino.

//LEDPins

intredPin=9;

intgreenPin=10;

intbluePin=11;

voidsetup(){

//setpinstoOUTPUT

pinMode(redPin,OUTPUT);

pinMode(greenPin,OUTPUT);

pinMode(bluePin,OUTPUT);

}

voidloop(){

//red

for(intfadeValue=0;fadeValue<=255;fadeValue+=5){

analogWrite(redPin,fadeValue);

delay(30);

}

for(intfadeValue=255;fadeValue>=0;fadeValue-=5){

analogWrite(redPin,fadeValue);

delay(30);

}

//green

for(intfadeValue=0;fadeValue<=255;fadeValue+=5){

analogWrite(greenPin,fadeValue);

delay(30);

}

for(intfadeValue=255;fadeValue>=0;fadeValue-=5){

analogWrite(greenPin,fadeValue);

delay(30);

}

//blue

for(intfadeValue=0;fadeValue<=255;fadeValue+=5){

analogWrite(bluePin,fadeValue);

delay(30);

}

for(intfadeValue=255;fadeValue>=0;fadeValue-=5){

analogWrite(bluePin,fadeValue);

delay(30);

}

//blue+increasingred

digitalWrite(bluePin,HIGH);

for(intfadeValue=0;fadeValue<=255;fadeValue+=5){

analogWrite(redPin,fadeValue);

delay(30);

}

//turnblueoffagain

digitalWrite(bluePin,LOW);

//green+increasingred

digitalWrite(greenPin,HIGH);

for(intfadeValue=0;fadeValue<=255;fadeValue+=5){

analogWrite(redPin,fadeValue);

delay(30);

}

//turngreenoffagain

digitalWrite(greenPin,LOW);

//turnoffred

digitalWrite(redPin,LOW);

//blue+increasinggreen

digitalWrite(bluePin,HIGH);

for(intfadeValue=0;fadeValue<=255;fadeValue+=5){

analogWrite(greenPin,fadeValue);

delay(30);

}

//turnblueoffagain

digitalWrite(bluePin,LOW);

//turnoffgreen

digitalWrite(greenPin,LOW);

//turnallontomakewhite

digitalWrite(redPin,HIGH);

digitalWrite(greenPin,HIGH);

digitalWrite(bluePin,HIGH);

delay(2000);

//turnalloff

digitalWrite(redPin,LOW);

digitalWrite(greenPin,LOW);

digitalWrite(bluePin,LOW);

}

UploadthesketchtoyourArduinoUnoconnectedtotheRGBLEDcircuityoujustbuilt.TheLEDshouldrepeatedlygothroughacoloursequence.

DIGGINGINTOTHECODE

Thecodegoesthroughalightsequencethatfirstlightsupthedifferentcoloursindividuallyandthenlightsupdifferentcombinationsofred,greenandbluetocreateothercolours.Thetopofthesketchstartbydefiningvariablesforeachpin:

//LEDPins

intredPin=9;

intgreenPin=10;

intbluePin=11;

Thesetup()thensetsthepinmodesforeachoftheLEDpins:

//setpinstoOUTPUT

pinMode(redPin,OUTPUT);

pinMode(greenPin,OUTPUT);

pinMode(bluePin,OUTPUT);

Theloop()thenstartsthecoloursequence.First,eachcolouroneachpinisfadedonandoff,onebyone,usingtwoforloopsforeachpin.Thefollowingcodeisjustfortheredpin,butitisrepeatedforthegreenandbluepins:

//red

for(intfadeValue=0;fadeValue<=255;fadeValue+=5){

analogWrite(redPin,fadeValue);

delay(30);

}

for(intfadeValue=255;fadeValue>=0;fadeValue-=5){

analogWrite(redPin,fadeValue);

delay(30);

}

Thentwopinsarelitupatatimetoshowwhattheresultinglightlookslike.Thefollowingcodeisforcombiningblueandred:

//blue+increasingred

digitalWrite(bluePin,HIGH);

for(intfadeValue=0;fadeValue<=255;fadeValue+=5){

analogWrite(redPin,fadeValue);

delay(30);

}

//turnblueoffagain

digitalWrite(bluePin,LOW);

Afterblueandredlightcomesblueandgreenlight.Finally,allthreecoloursareturnedonatthesametimeandthenturnedoffbeforethewholeloop()startsoveragain:

//turnallontomakewhite

digitalWrite(redPin,HIGH);

digitalWrite(greenPin,HIGH);

digitalWrite(bluePin,HIGH);

delay(2000);

//turnalloff

digitalWrite(redPin,LOW);

digitalWrite(greenPin,LOW);

digitalWrite(bluePin,LOW);

Youwillseethatyoucanstilltellthedifferencebetweenthered,greenandblueLEDsinsidetheRGBLEDwhentheyareallon.Itmaylookmorewhitethanwhenonlyoneortwoofthecoloursareon,butitwon’thavecompletelymixed.TheRGBLEDyouareusingisfairlycheap,andyoucanspendmoremoneyononesthatmixtheircoloursbetter,butthesearegreattousewhenyouarejuststartingout!

Asyou’llknowifyou’veeverpaintedsomething,twocolourscanbemixedtogethertocreateanewcolour.Forexample,ifyoumixblueandyellowpaintyougetgreenpaint.Mixingallthepaintcolourstogethercreatesblack—oratleastadarkcolourlikeblackorbrown.Itcanbetrickytoproduceblackwithoutbeingveryprecisewithexactlywhatcoloursyoumixtogether.

Thephysicsbehindmixingpaintcoloursiscalledsubtractivemixing.Mixinglightisdifferenttomixingpaint,however.Forexample,ifyoumixredandgreenlightitcreatesyellow;andifyoumixred,greenandbluelightitresultsinwhitelight.Thisprocessiscalledadditivemixing.SeeFigure6-8forexamplesofthetwotypesofmixing.YoucanresearchadditivemixingonlinetolearnmoreabouthowtocreatedifferentcolourswithyourRGBlight.

Figure6-8Mixinglightversusmixingpaint

CapacitiveSensingYouprobablydon’trealiseitbutyoualreadyinteractwithcapacitivesensorseveryday;forexample,mosttouchscreensonsmartphonesandmusicplayersusecapacitivesensors.What’sexcitingisthatyoucanuseanArduinotobuildyourowncapacitivesensor.

Capacitanceistheabilitytostoreanelectricalcharge.Haveyoueverwalkedacrossacarpetedroomthentouchedsomethinglikeacatorafriend’sarmandreceivedanelectricshock?Thatdemonstratesthatyoustoreelectricalcharge.Acapacitivesensordetectswhensomethingthatstoreschargeisnearby.

Capacitanceistheabilitytostoreanelectricalcharge.Electricalcomponentsbuiltespeciallytoholdchargearecalledcapacitors,butotherobjects—evenpeople—alsohavecapacitance.

Thecodethatsenseswhensomeoneistouchingorneartoacapacitivesensorisabitcomplicated.Unlessyouarereallyinterestedinthedetailsofhowitworks,youdon’tneedtodealwithalltheinsandoutsofthecode—luckily,that’swherelibrariescomein!

AddingaLibraryAlibraryisacollectionoffunctionsthatarebundledtogether.It’saneasywayofwritingbitsofcodethatotherpeoplecanuseandisalsoaneasywayofusingbitsofcodewrittenbyothers.Itmeansyoudon’thaveto“reinventthewheel”whenotherpeoplehavealreadydoneitforyou.SomelibrariesareincludedwiththeArduinoIDE,butwhenyouusealibrarythatisn’tincluded,youneedtodownloaditandputinaplacewheretheIDEknowstolook.

Alibraryisacollectionofreusablefunctionsincodethatcanbeimportedandusedinmultiplesketches.

Inthiscase,you’regoingtousethecapacitivesensinglibrarythatyoucandownloadfromhttp://playground.arduino.cc/Main/CapacitiveSensor.

1. Downloadandunzipthefolderfromhttps://github.com/arduino-libraries/CapacitiveSensor/zipball/master.Thefoldermaybecalledsomethinglikearduino-libraries-CapacitiveSensor-3e33f75—thelettersandnumbersattheendofthefilemightdiffer.InsideshouldbeafoldercalledlibrariesthatholdstwofoldersnamedCapacitiveSensorandCapacitiveSensorDue.

2. TheArduinoIDEonlylooksfornewlibrariesinoneplace:thelibrariesfolderinsideyoursketchbook.YoursketchbookisafoldercalledArduinoinsideyourDocumentsorMyDocumentsfolder,dependingonyouroperatingsystem.MovetheCapacitiveSensorandCapacitiveSensorDuefoldersandeverythinginthemintothelibrariesfolderinyoursketchbook(asshowninFigure6-9).

3. IftheArduinoIDEisalreadyopen,closeandrestartit;otherwise,justopenit.4. Tocheckwhetherthelibraryhasinstalledcorrectly,gotoSketch⇒ImportLibrary

andseeifCapacitiveSensorandCapacitiveSensorDueappearinthelistlikeinFigure6-10.AlsogotoFile⇒Examples,whereyoushouldseeCapacitiveSensorlisted.

Figure6-9PlacethedownloadedandunzippedfolderinthelibrariesfolderoftheArduinosketchbook.

Figure6-10Checkforthelibraryandexampleinthemenus.

Ifyoudon’tseetheexampleorlibrarylistedinyourmenus,tryrestartingtheArduinoIDE.Ifthatstilldoesn’tmakethemappear,gobackthroughthestepsandmakesureyouhaverenamedthedownloaded

foldercorrectlyandhaveputitinthecorrectlibrariesfolder.

WiringtheCircuitThecircuitforacapacitivesensorusestwopins.Onepinsendsoutasignaltoanantenna,thesecondpinlistenstothatsignalcomingbackin.Theantennacanbeanythingconductive.Foilworkswell,butyoucanalsoalwaysjustuseawirewithoutanythingconnectedtoit.Whenacapacitiveobject(likeyourfinger,forexample)isneartheantenna,thereceivedsignalischangedaccordingtohowclosethecapacitiveobjectis.Thelibraryreportsbackanumberthatcorrespondstohowcloseorfarawaythecapacitiveobjectis.

Youmaywanttosolderaplainpapercliptoawire(makesurethepaperclipdoesn’thaveaplasticcoating;youcanstripitwithwirestrippersifitdoes).Thenyoucanusethepapercliptoattachtoanobjectlikefoilandusethewiretoconnectthefoiltoyourbreadboard.

Thecircuitforacapacitivesensorusesaresistorbetweentheantennaandthesendingpin.Youneedtouseaverylargeresistor—atleast10MΩ(that’s10millionOhms)!BuildthecircuitshowninFigure6-11:

1. Insertonelegofa10MΩresistorinthemiddleofthebreadboard.Inserttheotherlegintoanyotherrow.

2. UseajumperwiretoconnectonesideoftheresistortoPin2ontheArduinoUnoandasecondjumperwiretoconnecttheothersideoftheresistortoPin4ontheArduinoUno.

3. ConnectanotherjumperwiretothesameshortrowonthebreadboardthatisconnectedtoPin2.Don’tconnecttheotherendofthejumperwiretoanything.Thisisnowyourantennaforyourcapacitivesensor.

Figure6-11Capacitivesensingcircuit

WritingtheCodeWhenyouareusingalibrary,thefirststepistotelltheArduinoIDEinyourcodewhatlibraryyouwanttouse.Youdothisbyusing#includeandthenthenameofthefilethatdescribesthelibrary,likethis:#include<CapacitiveSensor.h>

Thefileextensionis.h.The<and>meanthatthelibraryislocatedwheretheArduinoIDEwouldexpectittobe:thelibrariesfolderinthesketchbook.

ThelibraryusesanobjectcalledCapacitiveSensor.Thisobjecthandlesallthenitty-grittydetailsofinteractingwiththesensor.YouneedtocreateanewvariablethatisthetypeCapacitiveSensor.Itonlytakestwoarguments:thepinfromwherethesignalissentandthepinthesensorisconnectedto:CapacitiveSensorhandSensor=CapacitiveSensor(outputPin, sensorPin);

ThecapacitiveSensor()functioniscalledtoreadfromthesensor.CallthefunctiontypehandSensor.capacitiveSensor(),becausethefunctionbelongstotheCapacitiveSensorvariablehandSensor:longsensorValue=handSensor.capacitiveSensor(30);

Thereturnedvalueisstoredinalongdatatype.Alongislikeanint,butitcanholdmuchsmallerandbiggernumbers.Thereturnednumberfromthecapacitivesensormightbealargernumberthananintcanhold,soit’sbesttousethelargerdatatype.

Alongisadatatypethatcanholdwholeintegernumbersfrom–2,147,483,648to2,147,483,647.

Whenyouputallthecodetogether,itlookslikethefollowingsketch:#include<CapacitiveSensor.h>

//capSensepins

intsensorPin=2;

intoutputPin=4;

CapacitiveSensorhandSensor=CapacitiveSensor(outputPin, sensorPin);

voidsetup(){

//beginserialcommunication

Serial.begin(9600);

}

voidloop(){

//readinthevaluefromthesensor

longsensorValue=handSensor.capacitiveSensor(30);

//printthevalue

Serial.println(sensorValue);

//waitforashortwhilebeforecontinuing

delay(10);

}

UploadthesketchtoyourArduinoUnoandopentheSerialMonitorintheArduinoIDEonyourcomputer.Touchtheendofthejumperwireactingasyourantennaandwatchwhathappenstovaluesbeingprinted.

DIGGINGINTOTHECODE

Thereisn’talottothesketch—it’squiteshort,butlet’sgooveritinmoredetail.Atthetoparethevariablesforthesketch.Therearetwopinsthatthecapacitivesensorneeds:thepinconnectedtotheresistorandthepinconnectedtotheresistorandantenna:

//capSensepins

intsensorPin=2;

intoutputPin=4;

Insidethesetup(),theonlythingthathappensisthatserialcommunicationstarts:

//beginserialcommunication

Serial.begin(9600);

Theloop()isalsobrief.ItreadsinthecurrentvaluefromthecapacitivesensorandsavesitinthevariablesensorValue.ThatvariableisthenprintedtotheSerialMonitor.Adelay()isusedtopausetheloop()beforethewholeprocessrepeatsagain.

//readinthevaluefromthesensor

longsensorValue=handSensor.capacitiveSensor(30);

//printthevalue

Serial.println(sensorValue);

//waitforashortwhilebeforecontinuing

delay(10);

Whathappenswhenyoudon’ttouchtheexposedmetalpinofthejumperwireantennaandyouonlytouchtheplasticcoatingonthewire?

Tryaddingmore10MΩresistorstoincreasethesensitivityofyoursensor.Thatmeansthesensorwillbeabletodetectyourhandfromfartheraway.Addtheminseries—endtoend.Whenyoucombineresistorsinseries,thetotalresistanceisthesumoftheindividualresistors.Thisisusefulasit’spracticallyimpossibletobuyresistorswithvaluesgreaterthan10MΩ,butyoucanputmultipleresistorsinseriesandtothesensorcircuittheylooklikeonebigresistor.

BuildingaCrystalBallCapacitivetouchsensorscanappeartobequitemagical,eventhoughyouknowit’sjustelectricalengineering.Solet’sexaggeratetheexperienceandcreateacrystalballthatmysteriouslylightsupwhenyouwaveyourhandnearit,likeinFigure6-12.

Youcanmakeyourown“crystal”withpapiermachétissuepaperoveraballoon.It’sagreatwaytomakeasemi-transparentspherethatwilllightupnicelywhenyourRGBLEDisinside.

Figure6-12Atouch-sensitivecrystalball

WhatYouNeedYouwillneedthefollowingitemstomakeyourcrystalball.TheelectroniccomponentsarepicturedinFigure6-13.

AcomputerAnArduinoUnoAUSBcableAbreadboard8jumperwiresSolidcorewire3220Ωresistors410MΩresistorsAnRGBcommoncathodeLEDApaperclip9Vbattery9Vbattery-to-DCbarreljackconnector3sheetswhitetissuepaperAballoonThincardboardorthickpaperAluminiumfoilAsolderingironSolderScissorsorutilityknifePVAgluePaintbrush

Figure6-13Theelectroniccomponentsyouneedtomakethecrystalball

UnderstandingtheCircuitThecircuitforthecrystalballisacombinationoftheRGBLEDandcapacitive-sensingcircuitsyoumadeearlierinthisadventure.Itmightbeeasiertounderstandthecircuitbylookingatacircuitschematic,insteadoflookingatabreadboard,sotakealookatFigure6-14.

Figure6-14Circuitschematicforthecrystalball

PrototypingonaBreadboardIfyou’veworkedthroughtheearlieradventuresinthisbookyou’renowanexperiencedengineer,soyouknowhowimportantitistotrythingsoutonabreadboardbeforeyoustartsolderingeverythingtogether.However,Istillwanttoremindyoutodoit,justincaseyoufeellikerushingthroughthisstep.BuildthecircuitshowninFigure6-15:

1. UseajumperwiretoconnectaGNDpinontheArduinoUnotoalongrowalongthebottomofthebreadboard.Ifthebreadboardislabelledwithablackorbluelineor-,connectthepintothatrow.

2. PlacetheRGBLEDinthebreadboardsothateachlegisinitsownshortrow.UseajumperwiretoconnectthelongestlegoftheLEDtothelongrowconnectedtotheGNDpin.

3. Insertonelegofa220ΩresistorintothesamerowaseachofthecolourlegsoftheLED.Bendtheresistoroverthegapinthemiddleoftheboard,andinsertthelegofeachLEDintoitsownshortrow.

4. FindtheredlegandconnecttheresistornowconnectedtoittoPin9withajumperwire;repeattoconnecttheresistorconnectedtothegreenlegtoPin10;andrepeatasecondtimetoconnecttheresistorconnectedthebluelegtoPin11.

5. Attheotherendofthebreadboard,insertthelegsofa10MΩresistorintotwodifferentrowsinthemiddleofthebreadboard.

6. Insertthelegofasecond10MΩresistorintothesamerowasoneofthelegsofthefirstresistor.Insertthelastlegintoanemptyrow.

7. ConnectajumperwirefromPin2tooneoftheresistors(justdon’tconnectittotherowwheretheresistorsareconnectedtoeachother).Connectanotherjumperwireintothissamerow.Thisactsasyourantennaforyourprototypecircuit.

8. ConnectajumperwirefromPin4totheremainingresistorlegthatisn’tconnectedtoanythingelse.

Figure6-15Breadboardprototypecircuit

Afteryouhavebuiltyourbaseforyourcrystalballfrompaperandfoil,youusethebreadboardedcircuittodeterminehowmanyresistorsyouwouldlikeforyourcapacitivetouchsensor.Somewherebetweenoneandfourshouldberight.Youcanaddmoreresistorstoyourtworesistorsonthebreadboardendtoendthewaythetworesistorsarealreadyconnected.

WritingtheCodeThefirstfewlinesofthesketchareamash-upoftheRGBLEDsketchandcapacitivesensingsketchfromearlierinthisadventure.Inthiscode,thevariablesforthepinsandthesensoraresetup.Youwillbebuildingyourbaseinthenextsection.Itwillbecoveredinfoilandwillbetheantennaforyourcircuit,butfirstcreateanewsketchintheArduinoIDEwiththefollowingcode:#include<CapacitiveSensor.h>

//LEDpins

intredPin=9;

intgreenPin=10;

intbluePin=11;

//capSensepins

intsensorPin=2;

intoutputPin=4;

//touchthreshold

intthreshold=1000;

CapacitiveSensorhandSensor=CapacitiveSensor(outputPin,@@ta

sensorPin);

voidsetup(){

pinMode(redPin,OUTPUT);

pinMode(greenPin,OUTPUT);

pinMode(bluePin,OUTPUT);

Serial.begin(9600);

}

voidloop(){

longsensorValue=handSensor.capacitiveSensor(30);

Serial.println(sensorValue);

//ifabovethethreshold

if(sensorValue>threshold){

//calculatecolorvaluebasedonsensorreading

intredValue=map(sensorValue,threshold,90000,0,255);

intgreenValue=map(sensorValue,threshold,20000,0,255);

intblueValue=map(sensorValue,threshold,30000,0,255);

//turnonled

analogWrite(redPin,redValue);

analogWrite(greenPin,greenValue);

analogWrite(bluePin,blueValue);

}

else{

//otherwiseturnoffled

digitalWrite(redPin,LOW);

digitalWrite(greenPin,LOW);

digitalWrite(bluePin,LOW);

}

}

UploadthesketchtoyourArduinoUno,andtouchthejumperwireactingastheantenna.Youshouldseethelightturnonandchangecolours.OpentheSerialMonitorintheArduinoIDEtomonitorthevaluesbeingreadbythetouchsensor.

DIGGINGINTOTHECODE

Themainvariableyouusetoadjustyourinteractionwithyourcrystalballisthreshold.Thisvariableplaysinanimportantroleintheloop().ItdetermineshowsensitiveyourcrystalballisbykeepingtheLEDturnedoffuntilabig-enoughvalueisreadfromthesensor:

//touchthreshold

intthreshold=1000;

AdjustthisnumesensorintheSerialMonitor.Youmayhavetoadjustthisnumbermultipletimesasyourantennachangesfromaprototypejumperwiretoyourcrystalball.

Intheloop(),thresholddetermineswhenthelightsturnon:

//ifabovethethreshold

if(sensorValue>threshold){

Withinthatifstatement,therearethreelinesofcodeusinganewfunction:map().Thisfunctiontakesanumberwithinarangeofvaluesandtranslatesittoanewrangeofvalues.Thisisusefulbecausetherangeofnumbersthatcanbereadinfromthesensorcangetverylarge,butanalogWrite()can’thandleanythinglargerthan255.Themap()functionhelpsbyscalingthevaluefromthesensortoanewnumberthat’swithintheacceptablerange.Figure6-16illustrateshowthisworks.

Figure6-16MappingavaluetoanewrangeThefirstargumentofmap()isthenumbertobemapped.Thesecondandthirdargumentsarethecurrentlowestandhighestvaluesthosenumberscanbe.Thefourthandfifthnumbersarethenewlowestandhighestvaluesthemappednumberscanbe:

intredValue=map(sensorValue,threshold, 90000,0,255);

intgreenValue=map(sensorValue, threshold,20000,0,255);

intblueValue=map(sensorValue,threshold,30000,0,255);

Inthesketch,themaximumofthestartingrangeisdifferentforeachcolour.Thisistomakeeachofthecoloursrespondslightlydifferentlytothesamesensorvalue.Forexample,avalueof3000createsaredValueof6,greenValueof28andablueValueof18.Tryoutsomedifferentvaluesinthethreemap()functionstogetthecoloursyoulikebest.

MakingtheCrystalBallNowtomakethecrystalballitself.Youaregoingtousepapiermachétocreateathinspherethatwillletthroughlight.Thebaseonwhichtheballsitsisthincardboardorthickpapercoveredinaluminiumfoil.Thebaseservesasthecapacitivesensor.Theelectronicsfitnicelyinsidethebaseand,ifyouuseabatterytopowertheArduino,itwillcreateaperfectmagicalillusion.

MakingaPapierMachéBallThe“ball”ofthecrystalwillbepapiermachéthatgetsitshapefromaballoon.YouusetissuepaperinsteadofathickerpapersothatthelightfromtheRGBLEDisstillvisible.

1. Blowupaballoontothesizethatyouwantyourcrystalball.RememberthatifyouwanttheArduinoboardtofitinsidethebase,yourballoonneedstobebigenoughtorestinabasethatcanholdtheboard.

2. Waterdownaboutatablespoonor25mlofwhitePVAgluewithahalftofulltablespoonor15–25mlofwater.

3. Cutupthreesheetsofwhitetissuepaperintoapproximatelyone-inchbyone-inchsquares.

4. Useapaintbrushtoapplythegluemixturetoasmallsectionoftheballoonstartingatthetopoppositeoftheknot.

5. Placeatissuepapersquareonthegluedareaandbrushmoreglueontopofthepaper.6. Repeatsteps4and5workingtowardstheknotoftheballoon,takingcaretooverlap

thesquaresonlyatinybit,untilthetoptwo-thirdsoftheballooniscovered.7. Leavetheballoontodryforatleasthalfadayorovernight.8. Repeatwithanotherlayeroftissuepaper.Youmayneedtoapplyuptothreelayersof

tissue.Youwantthedriedpapiermachétofeelfirmenoughtosupportitsshapeafteryouhavepoppedandremovedtheballoon.

9. Whenthepapiermachéisdryandfeelsfirmenoughtoholditsshape,poptheballoon.Carefullypeelawaytheballoonfromtheinsideofthepapiermaché.Ifneeded,trimthepapertocreateaneatedgetothe“crystal”.YouwillendupwithanobjectliketheoneshowninFigure6-17.

10. Cutastripofthickerpaperorthincardboardabout2”wide.Wrapitinaluminiumfoil.

11. Curlthefoil-coveredpaperintoaringjustbigenoughtoresttheballonandwillalsofitaroundtheArduinoUno(seeFigure6-18).Securetheringwithastapleortape.

12. Attachtheballtotheringwithtapeorglue.

Figure6-17Papiermachécrystalball

Figure6-18Aluminiumfoil–coveredbase

SolderingtheElectronics

Therearen’tmanypartstothiscircuit,butbesuretoprototypeitonabreadboardfirstoryouwon’tknowhowmanyresistorstouseforyoursensor.

Solderingcanbedangerousastheirongetsveryhot.Onlysolderwhenanadultisnearbytohelp.

Soldera220ΩresistorontoeachoftheshorterthreelegsoftheRGBLED.Cutapieceofsolid-corewirethesamelengthasaresistorandsolderittothecathodeoftheRGBLED(seeFigure6-19).

Figure6-19SolderedLEDcircuit

Soldertogetherthenumberof10M-ohmresistorsyouneedforyourcircuit.

Cutapieceofsolid-corewireabout3”long.Solderoneendtoapaperclipandtheotherendtothelast10M-ohmresistorinyourchainofresistors(seeFigure6-20).

Figure6-20Solderedsensorcircuit

ConnectingtheElectronicsInserttheendoftheresistorsnotsolderedtothewireintoPin4andthewireconnectedtothepaperclipintoPin2.Inserttheresistorsconnectedtothered,greenandbluepartsoftheRGBLEDintoPins9,10and11(seeFigure6-21).Attachthepaperclipontothealuminiumfoilbaseofthecrystalball.

Figure6-21Completedcrystalballcircuit

PowertheArduinoboardusinga9VbatteryandDCbarreljackconnector.Tryoutyourcrystalballbywavingyourhandsoverit!Thecrystalballshouldonlylightupwhenyourhandisnearandchangecolourswhenyourhandgetsclosertothealuminiumbase.Remember,youmayneedtoadjustthethresholdvalueuntilyougettheinteractionthatyouwant.

FurtherAdventureswithLibrariesYouhavelearnedhowtostrikeoutonyourownandstartusingotherlibrarieswithyourArduino.Awholeworldofpossibilitieshasopenedup!ExploretheArduinoPlayground(http://playground.arduino.cc/)toseewhatotherlibrariesareavailable.

Ifyou’dliketoreadmoreonhowtousecapacitivesensing,visittheArduinoPlaygrounddocumentationathttp://playground.arduino.cc/Main/CapacitiveSensor.

ArduinoCommandQuickReferenceTable

Command Description

analogWrite()Outputsavoltagebetween0and5Vonaspecifiedpin.Avalueof0outputs0Vand255outputs5V.Seealsohttp://arduino.cc/en/Reference/AnalogWrite.

CapacitiveSensorLibraryforcreatingcapacitivesensors.Seealsohttp://playground.arduino.cc/Main/CapacitiveSensor?from=Main.CapSense.

longAlongisadatatypethatcanholdwholeintegernumbersfrom–2,147,483,648to2,147,483,647.Seealsohttp://arduino.cc/en/Reference/Long.

map()Takesavaluewithinaninitialrangeandmapsittoanewrange.Seealsohttp://arduino.cc/en/Reference/Map.

AchievementUnlocked:Youhaveexpandedyourknowledgewithlibraries!

IntheNextAdventureInthenextadventure,youstartexploringothertypesofArduinoboardstocreateacustomcomputergamecontroller!

WHENYOUSELECTyourArduinoUnoboardfromTools⇒BoardintheArduinoIDE,youmightnoticethatthatitisjustoneiteminaverylonglistofboardnames.Alltheotherssoundjustasexciting.So,whatmakesthemdifferentfromyourUno?There’snotroominthisbooktodescribeallofthembutinthisadventureyouwillgettoknowoneofthem—theArduinoLeonardo.TheLeonardohasaspecialskillthattheUnodoesn’thave:itcanmakeacomputerbelievethattheArduinoboardisaUSBkeyboardormouse.

Forthisadventure,youalsouseasensorthatdetectswhetherit’sinbrightlightorshadow.YouusethistocreateaUSBgamecontroller.Thesensormeansyouwillbeabletowaveyourhandsintheairabovethecontrollertoplaycomputergames!

WhatYouNeedYouneedthefollowingitemsforthefirstpartoftheadventure(seeFigure7-1):

Figure7-1Theelectroniccomponentsyouneedforthefirstpartofthisadventure

AcomputerAnArduinoLeonardoAUSBMicrocableAbreadboard4jumperwiresAlight-dependentresistorA10kΩresistor

IntroducingtheArduinoLeonardoOneofthemanygreatthingsabouttheArduinoplatformisthatyoucanchooseadifferentboardforyourprojectwithouthavingtochangethecode.YoucanusealmostallthecodeyouhavelearnedtowritefortheArduinoUnowiththeArduinoLeonardoaswell.YouevenusethesameArduinointegrateddevelopmentenvironment(IDE)touploadthecode.

ThemainthingyouhavetododifferentlyisthatwhenyouselectwhichboardyouareusingfromTools⇒BoardintheIDE,youneedtoselectArduinoLeonardo,asshowninFigure7-2.

Figure7-2SelectingtheArduinoLeonardofromTools⇒BoardintheArduinoIDE

ConnectingYourLeonardofortheFirstTimeThefirstthingyoumightnoticewhenconnectingyourArduinoLeonardotoyourcomputerforthefirsttimeisthatitdoesn’thavethesamekindofUSBconnectorasyourArduinoUno.Youcan’tusethesameUSBcableforbothboards.

TheconnectorsonUSBcablescomeindifferentsizesandshapes,asshowninFigure7-3.Whatyoumightthinkofasa“normal”USBcablehasaTypeAconnectoratoneend,whichgoesintoyourcomputer,andaTypeBconnectorattheotherend,whichgoesintoyourArduinoUno.TheArduinoLeonardousesaUSBMicroconnectorinsteadofaTypeBconnector.Thisdoesn’tdoanythingdifferentfromanormalUSBcable;itstillletstheLeonardogetpowerfromacomputerandcanbeusedtotalkwiththecomputer.Theonlydifferenceisthattheconnectorhasadifferentshape.ThatmeansyouhavetokeeptrackoftwodifferentkindsofUSBcable!

Figure7-3USBconnectors

OneofthefeaturestheLeonardohasthattheUnodoesn’tisthat,tothecomputer,theboardcanseemlikeaUSBkeyboard.Becauseofthis,whenyouconnectyourLeonardo,yourcomputermightpopopenawindowthatsaysthecomputerhasdetectedanewkeyboard.Justclosethewindow.Youdon’tneedtoclickContinueorsetupanewdevice;youprogramyourArduinoLeonardousingtheArduinoIDEjustlikeyouhavebeendoingwithyourArduinoUno.

IfthecomputeryouareusingtoprogramyourArduinoLeonardorunsonWindows7,youmayneedtoinstallsomeadditionaldrivers.ConnectyourLeonardoandwaitfortheautomaticdriverinstallationprocess.Ifnothinghappensafterafewminutes,gotohttp://arduino.cc/en/Guide/ArduinoLeonardoMicro?from=Guide.ArduinoLeonardoforinstructionsabouthowtoinstallthedriversyourself.

DIGGINGINTOTHECODE

Mostofthetime,thecodethatyouwriteforyourUnoworksthesamewayontheLeonardo,butit’sgoodtoknowwhatmightbealittledifferent.

WithyourArduinoUno,everytimeyouopentheSerialMonitorintheArduinoIDE,theUnoresets.Thesetup()functionthenrunsoncebeforegoingintoloop().Thesameisn’ttrueforyourLeonardo.TheLeonardodoesn’tresetwhentheSerialMonitorisopened.ThatmeansthatifyouwanttoprintsomethingtotheSerialMonitorfromthesetup()function,itdoesn’tappear;bythetimetheSerialMonitoropens,theprintstatementfromthesetup()functionwouldalreadyhavepassedandyou’donlyseemessagesfromtheloop.

IntheArduinoIDE,createanewsketchwiththefollowingcode.UploadittoyourLeonardoandthenopentheSerialMonitor:

voidsetup(){

Serial.begin(9600);

Serial.println("Hellofromthesetup!");

}

voidloop(){

Serial.println("Andhellofromtheloop!");

delay(1000);

}

Youonlyseethemessage“Andhellofromtheloop!”printedoverandoveragain.

NowtrypressingtheresetbuttonontheLeonardoboard(it’snexttotheUSBMicroconnector).ThemessagesstopprintingtotheSerialMonitorcompletely!ThisisbecausetheconnectionbetweentheSerialMonitorandtheLeonardowasbrokenwhenyoupressedreset.YouneedtocloseandreopenSerialMonitortolettheArduinoLeonardoknowthattheSerialMonitoristhereandwaiting.

Sowhatdoesthatallmean?Doesthatmeanyoucan’teverprintmessagesfromthesetup()functionofanArduinoLeonardotoreadintheSerialMonitor?Thatwouldbefrustrating!Itcanbereallyusefultoprintmessages,asithelpsyoutoknowwhatisgoingoninsidetheboardandfixanyproblemswithyourcode.Well,thegoodthingisthereisawayaroundthis.

YoucantelltheLeonardotowaitandnotdoanythinguntilaserialconnectiontosomethinglikeSerialMonitorisopened.

TryuploadingthefollowingcodetoyourLeonardo,andthenopentheSerialMonitor:

voidsetup(){

Serial.begin(9600);

while(!Serial);//sitandwaitforaserialconnection

Serial.println("Hellofromthesetup!");

}

voidloop(){

Serial.println("Andhellofromtheloop!");

delay(1000);

}

Youshouldnowseethe“Hellofromthesetup!”messagebeforethe“Andhellofromtheloop!”messages.Ifyoutrypressingresetontheboard,youseethatyoustillneedtocloseandreopentheSerialMonitortoseetheprintingmessagesagain.

ActingLikeaKeyboardYoucansendmessagestothecomputerfromyourArduinoUnousingfunctionslikeSerial.println(),butyouneedaspecialprogramliketheSerialMonitorintheArduinoIDEtobeabletoreadthosemessages.TheArduinoLeonardocansendmessagesthatdon’tneedaspecialprogramforthecomputertounderstand.Itcansendmessagesthatlooklikekeysbeingpressedonakeyboard.Anyprogramthatrespondstokeypresses(likeawordprocessingprogramoracomputergame)canunderstandthosemessages.

StartbycreatinganewsketchintheArduinoIDE.Writeoutthefollowingcodetocreateanemptysetup()andloop():voidsetup(){

}

voidloop(){

}

BeforeyoustartturningyourArduinoLeonardointoakeyboard,it’sveryimportantthatyougiveitanoffswitch.YourLeonardooverridesyourcomputer’skeyboardthesamewayaspluggingaUSBkeyboardintoyourcomputerdoes.IfyourLeonardoisconstantlytypingmessagesatyourcomputer,itcanbedifficulttotellyourcomputertodoanythingelse—includinguploadinganewsketchtoyourLeonardo.

Topreventthisfromhappening,intheloop()youaregoingtofirstchecktoseeifaninputpinissetto0.Ifitis,thendon’tprintanykeyboardmessages.Youdon’tevenneedtowireupaswitchlikeyoudidinAdventure3;youcanjustuseajumperwire!Here’show.

First,atthetopofyoursketch,beforethesetup(),createanewvariabletostoreyourswitchpinnumber:intswitchPin=4;

Insidethe{and}ofsetup(),setthatpintobeaninputwiththepull-upresistorturnedon:pinMode(switchPin,INPUT_PULLUP);

Theninloop(),addthefollowingcodetocheckifswitchPinhasbeenconnectedtoground.Ifithas,continueontoprintthemessage;otherwisedonothing://readthepushbutton:

intswitchState=digitalRead(switchPin);

//iftheswitchisopen(notconnectedtoground),

if(switchState==LOW){

//addkeyboardcodehere

}

delay(500);

Thepurposeofdelay()attheendistoslowdownhowoftenthelooprepeats.Thatway,

whenmessagesarebeingsent,theyaren’tsenttoofast.

NowifyouconnectawirebetweenswitchPin(Pin4)andGND,thecodethatyouputinsidetheifstatementisrun.Ifyoudon’tconnectanythingtotheswitchPin,thepull-upresistorcausesthevaluereadfromswitchPintobe1andthecodeinsidetheifstatementisskipped.

Timetostartaddingsomekeyboardmessages!

TheKeyboardfunctionslookalotliketheSerialfunctions.Inthesetup()functionyouneedtostarttheLeonardo’skeyboardmessagingbycalling:Keyboard.begin();

YoucanthenwritemessagesusingKeyboard:Keyboard.println("ThisisyourLeonardoactinglikeakeyboard.");

Whenthecodeisallputtogether,yougetthefollowingsketch:intswitchPin=4;//inputpinforswitch

voidsetup(){

//maketheswitchPinandinput

//withaninternalpull-upresistor

pinMode(switchPin,INPUT_PULLUP);

//initializecontroloverthekeyboard:

Keyboard.begin();

}

voidloop(){

//readthepushbutton:

intswitchState=digitalRead(switchPin);

//iftheswitchisopen(notconnectedtoground),

if(switchState==LOW){

Keyboard.println("ThisisyourLeonardoactinglikeakeyboard.");

}

delay(500);

}

UploadthecodetoyourLeonardoandthenopenanywordprocessingprogram.UsethejumperwiretoconnectyourswitchPintoGND.YoushouldseeyourLeonardotypingoutmessageslikethoseinFigure7-4!

Figure7-4TheLeonardotypinginawordprocessingprogram

Don’tcreatearunawaykeyboard!IfyoufindyouarehavingproblemsuploadinganewsketchtoyourLeonardo,thereissomethingyoucantry.YoucanmanuallyresettheArduinoLeonardoandtellittolistenforasketchtobeuploaded.HolddownthebuttonontheLeonardoandthenclickontheUploadbuttonintheArduinoIDE.WaituntiltheIDEsays“Uploading…”andthenreleasethebutton.Yoursketchshouldthenfinishuploadingontoyourboard.

DidyouknowyoucancomeupwithanewideausinganArduino,thenmakeandsellyourideaasaproductinastore?TheMaKeyMaKeyisoneexampleofanArduinoprojectyoucanbuyinastore.TheMaKeyMaKeyisbasedontheLeonardoArduino—itsnamecomesfrom“Makeanythingintoakeyboard”.Younowknowalotaboutthecodebehindhowitworks.Ifyou’dliketolearnmoreabouttheMaKeyMaKey,gotohttp://makeymakey.com,whereyoucandownloadtheArduinocodeusedtoprogramtheMaKeyMaKeyandreadhowitworks.YoucaneventurnyourArduinoLeonardointoaMaKeyMaKey!

ThisisallbecausetheArduinoisopensourcehardwareandtheArduinoisopensourcesoftware.Youcanreadmoreaboutwhatthatmeansonlineathttp://en.wikipedia.org/wiki/Open-source_softwareandhttp://en.wikipedia.org/wiki/Open-source_hardware.

SensingLightInAdventure2youwereintroducedtoanalogueinputs,usingthepotentiometertocontrolastatusmessagesign.Here’salittlerefresherabouthowanalogueinputswork.

AnanalogueinputonanArduinoboardisaninputthatcanreadinvoltagesbetweengroundand5V.Adigitalinputcanreadineithergroundor5V,anditcan’ttellifaninputisonly2.3Voranyothervaluebetweengroundand5V(seeFigure7-5).

Figure7-5Analogueanddigitalsignals

Therearealotofdifferentsensorsthatoutputanaloguesignalsandnotdigitalsignals—thatistheydon’tdetectonlywhethersomethingisonoroff;theyalsomeasurehowmuchthereisofsomething.Microphonesmeasuresound,accelerometersmeasuremovementandlightsensorsmeasurelight.Allofthesesensorsoutputananaloguesignal,whichwouldbereadintoanArduinoboardasananalogueinput.Thetypeoflightsensoryouworkwithinthisadventureisalight-dependentresistor(LDR).AnLDRisaresistorthatchangesitsresistanceaccordingtohowmuchlightitisexposedto.SometimesLDRsarealsocalledphotoresistors.IlikethenameLDRbecauseisdescribesexactlyhowtheresistorworks—itdependsonthelight.

Alight-dependentresistor(LDR)changesitsresistanceaccordingtohowmuchlightitisexposedto.Itisalsosometimescalledaphotoresistor.

UseamultimetertomeasuretheresistanceofyourLDR.ConnectoneprobetoonelegoftheLDRandtheotherprobetotheotherleg.Setthemultimetertomeasureresistanceandseewhatvalueyouget.Try

shiningalightontheLDRtoseewhathappens.WhathappenswhenyoucovertheLDRandblockoutlight?

BuildingtheCircuitAnArduinoboardcanonlymeasurevoltage,butanLDRonlychangesitsresistance,whichmakesforabitofapuzzle.HowcanyougettheArduinotoseehowtheLDRisrespondingtobrighterordarkerenvironmentsiftheLDRonlychangesresistanceandnotvoltage?Thetrickistousesomeclevercircuitdesign.

Voltage,currentandresistanceareallconnected.Youcan’tchangeoneofthosethingsinacircuitwithoutchangingtheothers.ThewaytheyareallrelatedisdefinedbyOhm’sLaw,whichisshowninFigure7-6.

Figure7-6Ohm’sLawdefineshowvoltage,currentandresistancearerelated.

Ohm’sLawisthemathematicalrelationshipbetweenvoltage,currentandresistance.Voltageequalscurrentmultipliedbytheresistance—or,putanotherway,V=IR.

Youdon’thavetoworrytoomuchaboutthedetailsofthatequationrightnow.Theimportantthingtoknowisthatyoucandesignacircuitthatchangesthevoltagewhenyouchangetheresistance.Thetypeofcircuityouaregoingtobuildtodothisiscalledavoltagedivider.

Avoltagedividerisacircuitthatoutputsafractionoftheinputvoltage.Itisausefulcircuitfortranslatingachangeinresistanceintoachangeinvoltage.

Thevoltagedivideryouaregoingtomakehastwodifferentresistors.Oneoftheresistorsisa“normal”fixed-valueresistor;theotherisavariableresistorthatchangesitsvalue.YouaregoingtouseanLDRasthevariableresistorhere,butinafutureprojectyoucouldbuildthiscircuitwithanothersensorthatisavariableresistor.

WhentheresistanceoftheLDRgoesupordown,theoutputvoltagegoesupordown.SowhenmoreorlesslightisshownontheLDRinthevoltagedividercircuit,theoutputvoltagegoesupanddown.WhetheryouputtheLDRinthetoporbottompositionaffectswhetherthevoltagegoesupordownwhenyoublockoutlightfromtheLDR.Figure7-7showstwowaysthatanLDRcanbebuiltintoavoltagedividercircuit.

Figure7-7Twovoltagedividercircuits,onewithanLDRasthetopresistanceandtheotherwithanLDRasthebottomresistance

Somepeoplefinditeasiertounderstandhowsomethingworkswhenitisdescribedwithamathematicalequation.Ifyouwouldliketoworkouthowthevoltageoutputfromthecircuitchangeswhenyouchangetheresistorvalues,youcanusetheequationshowninFigure7-8.Ifyoudon’tenjoyworkingwithnumbersandequations,thenyoucanjustignorethatfornowandinsteadhaveagoatbuildingthecircuitsoyoucanactuallyseewhatishappening.

Figure7-8Theequationtocalculatehowdifferentresistorvaluesinavoltagedividerchangetheoutputvoltage

WritingtheCodeOneofthegreatthingsaboutworkingwithArduinoboardsisthattheboarddoesn’tcarewhatsensorisconnectedtoitsinputpins.Itonlycaresifitisoutputtingananalogueordigitalsignal.Ifyou’veworkedthroughAdventure2,youalreadyhaveseenalltheArduinocodetoreadinthevaluesfromyourLDR—it’sthesamecodeyouwouldusetoreadfromapotentiometer.OpentheexamplecodeatFile⇒Examples⇒01.Basics⇒AnalogReadintheArduinoIDEtoseeanexamplesketchthatreadsinthevaluefromanalogueinputA0andthenprintsthatvaluetotheSerialMonitor.

IntheAnalogReadsketch,thesetup()functionstartstheserialcommunication://thesetuproutinerunsoncewhenyoupressreset:

voidsetup(){

//initializeserialcommunicationat9600bitspersecond:

Serial.begin(9600);

}

Theloop()functionreadsinthevalueonAnalogPinA0andsavesitinavariablecalledsensorValue.ThatvariableisthenprintedtotheSerialMonitor://thelooproutinerunsoverandoveragainforever:

voidloop(){

//readtheinputonanalogpin0:

intsensorValue=analogRead(A0);

//printoutthevalueyouread:

Serial.println(sensorValue);

delay(1);//delayinbetweenreadsforstability

}

CHALLENGE

BuildthevoltagedividercircuitwiththeLDRinthetoppositionanduploadtheAnalogReadSerialsketchtoyourArduinoboard.OpenSerialMonitorandobservewhathappenswhenyoushineorblocklightfromthesensor.

SwaptheLDRandfixedvalueresistorsotheLDRisnowinthebottomposition.WatchwhatvaluesareprintedintheSerialMonitor.Whenmightyouwanttousethefirstcircuit,andwhenmightyouprefertousethesecondone?

BuildingaGameControllerYounowknowhowtogetanArduinoLeonardotoactlikeaUSBkeyboard.Doyoualsoliketoplaycomputergames?Ifyoudo,youprobablycanthinkofsomegamesyoucanplayusingonlythekeyboardasinput.Ifyoudon’tplayalotofcomputergames,that’sokay;Icanpointoutsomethatyoucantry!

IfyoucangetyourLeonardotoactlikeakeyboardthatcontrolsacomputergame,thenyoucanstartdesigningyourowngamecontrollerliketheoneinFigure7-9.Thatopensupawideworldofdifferentsensorsthatyoucanusetoplayagame.Boringbuttonsareathingofthepast!You’regoingtobuildacontrollerthatuseslighttocontrolkeypresses,butyoucoulduseanysensoryoulike!

Figure7-9ArduinoLeonardogamecontroller

Youwatchavideoonhowtobuildyourcontrolleronthecompanionsite(www.wiley.com/go/adventuresinarduino).

WhatYouNeedYouneedthefollowingsuppliestomakeagamecontroller(Figure7-10showstheelectroniccomponentsyouneed):

Figure7-10Theelectroniccomponentsyouneedtomakethegamecontroller

AcomputerAnArduinoLeonardoAUSBMicrocableAbreadboard10jumperwires410kΩresistors4light-dependentresistorsApieceofpaperorcardtocoverthebreadboardSomemarkersorcolouredpencilsApairofscissorsorautilityknife

BuildingtheCircuitThecircuitforthegamecontrollerdoesn’tneedtohaveanyextensionwiressolderedtoit,soyoucanbuilditdirectlyonyourbreadboard.

Thegamecontrollercircuitconsistsofthesamecircuitrepeatedfourtimes.TherearefourLDRs;eachonecontrolsadifferentarrowkey.EachLDRisinitsownvoltagedividercircuitwithafixedvalueresistor.Figure7-11showsthecircuitschematicforthegamecontroller.

Figure7-11Circuitschematicforthegamecontroller

UsethefollowingstepstobuildthecircuitinFigure7-12onyourbreadboard.It’sgoodtospaceouttheLDRssotheyaren’ttooclosetoeachother.Youdon’twanttoaccidentallyblockthelightfromaLDRwhenyouaretryingtoblocktheLDRnexttoit:

Figure7-12Thegamecontrollercircuit

1. PositionthefourLDRsbyspanningthegapinthemiddleofthebreadboard.2. Connecteachoftheresistorsbetweenoneofthelongrowsalongthetopofthe

breadboardandtheLDRs.3. ConnectajumperfromthebottomlegofeachoftheLDRstoalongrowonthe

bottomofthebreadboard.4. Connectthelongrowalongthetop,connectingtheresistorstothe5Vpinonthe

ArduinoLeonardo.5. Useajumperwiretoconnectthelongrowalongthebottomofthebreadboardwith

theotherjumperwirestoaGNDpinontheArduinoLeonardo.6. Usingfourjumperwires,connectpinsA0,A1,A2andA3toeachoftheLDRs.One

endofthejumperwireplugsintothepinontheArduinoLeonardoandtheotherendplugsintothesamerowastheresistorlegandLDRleg.

WritingtheCodeInordertomakesureyourcircuitisworkingproperly,youfirstprogramtheLeonardotoprintmessagestotheSerialMonitorbeforeprogrammingittoactlikeakeyboard.Afteryouknoweverythingisokaywiththecircuitandyou’vefiguredoutthethresholdsforwhenthesensorshouldtriggeramessage,youreplacetheserialmessageswithkeyboardmessages.

StartbycreatinganewArduinosketchandcreatinganemptysetup()andloop():

voidsetup(){

}

voidloop(){

}

Atthetopofthesketchbeforesetup(),declareandinitialisethevariablesfortheinputpins.Therearefiveinputs:theswitchpinandoneinputforeachofthefourLDRs:intswitchPin=4;

intleftSensor=A0;

intrightSensor=A1;

intupSensor=A2;

intdownSensor=A3;

Insidesetup()startserialcommunicationandsetthepinmodefortheswitchPin://maketheswitchPinaninputwithaninternalpull-upresistor

pinMode(switchPin,INPUT_PULLUP);

//initializecontroloverthekeyboard:

Serial.begin(9600);

Insidetheloop(),checkthestateofswitchPinandcreateanifstatementthatistrueifswitchPinisLOW://readthepushbutton:

intswitchState=digitalRead(switchPin);

//iftheswitchisopen(notconnectedtoground),

if(switchState==LOW){

}

delay(50);

Thedelay()makessuremessagescan’tbesenttooquickly.

Atthetopofyourcodewithyourothervariables,addthefollowinglinesofcode:intrightThreshold=400;

intleftThreshold=400;

intupThreshold=400;

intdownThreshold=400;

ThesevariableskeeptrackofwheneachLDRcircuitwilltriggeramessage.

Youprobablyneedtouseavalueotherthan400foryourLDRs.Youmayneedtomakethevalueshigherorlower,andeachLDRmightevenrequireadifferentvalue!Lateryouwillfigureoutthebestvaluesforyourcontrollerbytryingoutdifferentvalues,butyouaren’treadytodothatyet!Youneedtofinishthesketchfirst.

Insideyourifstatement,addthefollowingcode.Eventhoughit’slong,it’sjustthesamethingrepeatedfourtimes—onceforeachLDR://RIGHTARROW

intrightValue=analogRead(rightSensor);

//Serial.println(rightValue);

if(rightValue>rightThreshold){

Serial.println("rightarrow");

}

//LEFTARROW

intleftValue=analogRead(leftSensor);

//Serial.println(leftValue);

if(leftValue>leftThreshold){

Serial.println("leftarrow");

}

//UPARROW

intupValue=analogRead(upSensor);

//Serial.println(upValue);

if(upValue>upThreshold){

Serial.println("uparrow");

}

//DOWNARROW

intdownValue=analogRead(downSensor);

//Serial.println(downValue);

if(downValue>downThreshold){

Serial.println("downarrow");

}

Ineachofthefourblocksofcode,thevaluefromtheanalogpinisreadinandsavedtoavariable.IfthatvariableislessthanthethresholdvaluefortheLDR,thenthemessageisprinted.

Insideeachblockofcodeisalineofcodecommentedout.Ifyouuncommentthatline(bydeleting//)thenthevalueofthatpinisprinted.Thiscanbeusefultohelpsetyourthresholdvalues,butitalsoprintsalotofnumbersandcanbeconfusing.Youprobablywanttouncommentonlyoneofthematatime.

Whatfollowshereisthefullcodefortryingoutprintingserialmessages.BuildyourcircuitanduploadthecodetoyourArduinoLeonardo.

Rememberthatyoursketchwon’tcheckthevaluesofthepinsunlessyouhaveconnectedPin4toGND!

intswitchPin=4;

intleftSensor=A0;

intrightSensor=A1;

intupSensor=A2;

intdownSensor=A3;

//adjustthesevariablestovaluesthat

//workforyourcontroller

intrightThreshold=400;

intleftThreshold=400;

intupThreshold=400;

intdownThreshold=400;

voidsetup(){

//maketheswitchPinaninput//withaninternalpull-upresistor

pinMode(switchPin,INPUT_PULLUP);

//initializecontroloverthekeyboard:

Serial.begin(9600);

}

voidloop(){

//readthepushbutton:

intswitchState=digitalRead(switchPin);

//iftheswitchisopen(notconnectedtoground),

if(switchState==LOW){

//RIGHTARROW

intrightValue=analogRead(rightSensor);

//Serial.println(rightValue);

if(rightValue>rightThreshold){

Serial.println("rightarrow");

}

//LEFTARROW

intleftValue=analogRead(leftSensor);

//Serial.println(leftValue);

if(leftValue>leftThreshold){

Serial.println("leftarrow");

}

//UPARROW

intupValue=analogRead(upSensor);

//Serial.println(upValue);

if(upValue>upThreshold){

Serial.println("uparrow");

}

//DOWNARROW

intdownValue=analogRead(downSensor);

//Serial.println(downValue);

if(downValue>downThreshold){

Serial.println("downarrow");

}

}

delay(50);

}

Asthesketchesgetlonger,youmayprefertodownloadthemfromthecompanionsite(www.wiley.com/go/adventuresinarduino)insteadoftypingthemout.

NowopentheSerialMonitorandtryoutyourLDRsonebyone,byholdingyourhandovereachone.Adjustthethresholdvaluesuntiltheyprintamessageonlywhenyouwantthemto.

Afteryouknowwhatyourthresholdsshouldbe,youcanchangeyoursketchtooutputkeypressesinsteadofserialmessages.

Saveyoursketchandthencreateanewemptysketch.Copyandpastethesketchthatyoujustsavedintothenewsketch.YouaregoingtokeepmostofwhatyouhavealreadywrittenandreplacethelinesofcodethatuseSerialfunctionswithKeyboardfunctions.

Inthesetup(),replacethelinethatstartsserialcommunicationwiththefollowing://initializecontroloverthekeyboard:

Keyboard.begin();

Ineachofthefourblocksofcodethatprinttheserialmessageaboutwhichsensorwastriggered,replacetheSerial.println()withthefollowingline,usingKEY_RIGHT_ARROW,KEY_LEFT_ARROW,KEY_UP_ARROWandKEY_DOWN_ARROW:Keyboard.press(KEY_RIGHT_ARROW);

Insteadofprintingamessage,theLeonardoissendingamessagethatakeyhasbeenpressed.Attheendoftheloop,thefollowinglineofcodesendsthemessagethatallthekeyshavebeenreleased:Keyboard.releaseAll()

Whenyouputitalltogether,youhavethefollowingsketch:intswitchPin=4;

intleftSensor=A0;

intrightSensor=A1;

intupSensor=A2;

intdownSensor=A3;

//adjustthesevariablestovaluesthat

//workforyourcontroller

intrightThreshold=400;

intleftThreshold=400;

intupThreshold=400;

intdownThreshold=400;

voidsetup(){

//maketheswitchPinandinput//withaninternalpull-upresistor

pinMode(switchPin,INPUT_PULLUP);

//initializecontroloverthekeyboard:

Keyboard.begin();

}

voidloop(){

//readthepushbutton:

intswitchState=digitalRead(switchPin);

//iftheswitchisopen(notconnectedtoground),

if(switchState==LOW){

//RIGHTARROW

intrightValue=analogRead(rightSensor);

//Serial.println(rightValue);

if(rightValue>rightThreshold){

Keyboard.press(KEY_RIGHT_ARROW);

}

//LEFTARROW

intleftValue=analogRead(leftSensor);

//Serial.println(leftValue);

if(leftValue>leftThreshold){

Keyboard.press(KEY_LEFT_ARROW);

}

//UPARROW

intupValue=analogRead(upSensor);

//Serial.println(upValue);

if(upValue>upThreshold){

Keyboard.press(KEY_UP_ARROW);

}

//DOWNARROW

intdownValue=analogRead(downSensor);

//Serial.println(downValue);

if(downValue>downThreshold){

Keyboard.press(KEY_DOWN_ARROW);

}

}

delay(50);

Keyboard.releaseAll();

}

Buildthecircuitanduploadthesketch.Openaspreadsheetprogram,suchasMicrosoftExcel,andtestthatyoucanuseyourcontrollertomovetodifferentsquaresjustasyoucouldwiththearrowkeys.

Doesyourgameusekeysotherthanthearrows?Ormaybeitneedsthearrowkeysandthespacebar?YoucanreadmoreaboutallthekeystheArduinoLeonardocanpressontheArduinowebsiteathttp://arduino.cc/en/Reference/KeyboardModifiers.

MakingtheControllerCoverUsingpaperorcard,cutoutashapeforyourgamecontroller.Itcanbearectangleoranyothershape.Itdoesn’thavetolooklikeanygamecontrolleryou’veeverseenbefore!Itjustneedstobebigenoughtocoveryourbreadboard.

Decorateyourcoverhoweveryou’dlike.ItwouldbeagoodideatolabelwhichkeyistriggeredbywhichLDR.Whenyou’reatatrickypartinyourgame,youdon’twanttoforgetwhichsensoriswhichkeyandaccidentallyloseyourgame!

Usingscissors,pokeaholewhereeachLDRwillbeplaced(seeFigure7-13).ThisiswherethewirelegsoftheLDRwillpassthroughthecoversothatthetoppartofthesensorisabovethecover,butthelegsareconnectedtothecircuitunderneathonthebreadboard.

Figure7-13Coverwithoutanycircuitry

PuttingItAllTogetherSinceyou’vealreadytestedyourcontrollerwithaspreadsheetprogram,thelaststepistoaddyourcontrollercoverbeforeplayingyourgameswithyournewcontroller.

Onebyone,removeanLDRfromthebreadboardandpokeitslegsthroughtheholesinthepapercover.ThenconnectthatLDRbackintothecircuitonthebreadboard.YoucanalwayssolderlongerwiresontotheLDRsifyoufindittootrickytoconnecttheLDRsbackintocircuitonthebreadboard.

Testyourcontrolleragainwiththespreadsheetprogramjusttomakesureyou’veconnectedeverythingcorrectly.Afteryou’veconfirmedthatit’sallokay,loadupyourfavoritegamethatusesthearrowkeysandstartplaying!

Ifyouarelookingforsomegamestoplaywithyournewcontroller,2048athttp://gabrielecirulli.github.io/2048isagoodonetotry.It’sanumberpuzzlegame.Ialsolikethemazegameatwww.primarygames.com/puzzles/mazes/mazerace.It’smuchharderthanitlooks!

FurtherAdventureswiththeLeonardoYouhavenowstartedworkingwithmoreadvancedcircuitscalledvoltagedividers.Ifyouwouldliketolearnevenmoreaboutvoltagedividers,youcanstartbycheckingoutSparkfun’stutorialathttps://learn.sparkfun.com/tutorials/voltage-dividers.

FormoreinformationabouttheArduinoLeonardoandwhatyoucandowithit,visittheArduinoLeonardopageontheArduinowebsiteathttp://arduino.cc/en/Guide/ArduinoLeonardoMicro?from=Guide.ArduinoLeonardo.

YoucanalsoexploremoreexamplesusingtheKeyboardfunctionsintheArduinoIDEbygoingtoFile⇒Examples⇒09.USB.Here,youwillalsofindexamplesthatturnyourArduinoLeonardointoamouse.

BoardsliketheArduinoLeonardoandUnoareopensourcehardware.ThatmeansthatyoucanmakenewprojectsandevennewboardsthatusethefeaturesofArduinos,justliketheMaKeyMaKey.Ifyouwouldliketolearnmoreaboutopensourcehardware,checkouttheOpenSourceHardwareAssociation(OSHWA)atwww.oshwa.org/.

ArduinoCommandQuickReferenceTable

Command Description

While(!Serial); CausestheLeonardotowaitanddonothinguntilaserialconnectionisopened.

Keyboard.begin() Beginskeyboardfunctionality.Seealsohttp://arduino.cc/en/Reference/KeyboardBegin.

Keyboard.println()Sendsamessagetothecomputerasifitwastypedonthekeyboard.Seealsohttp://arduino.cc/en/Reference/KeyboardPrintln.

Keyboard.press()Sendsamessagetothecomputerthatakeyispressed.Seealsohttp://arduino.cc/en/Reference/KeyboardPress.

Keyboard.releaseAll()Sendsamessagetothecomputerthatallkeyshavebeenreleased.Seealsohttp://arduino.cc/en/Reference/KeyboardReleaseAll.

AchievementUnlocked:Expertconstructorofagamecontroller.Wellplayed!

IntheNextAdventureInthenextadventure,youcontinueyourexplorationofothertypesofArduinoboardstocreateanamazingwearablecircuit!

YOUHAVEONLYjustbeguntoexploreallthedifferentwaystomakeaprojectwithanArduino!InAdventure7youlearnedhowtodesignandbuildyourowngamecontrollerusingtheArduinoLeonardo.TheArduinoboardstilllookedexactlylikeanArduinoUno,however,andyoustillbuiltcircuitsthesamewayyouwouldbuildyourcircuitforanArduinoUnoproject—usingbreadboards,wireandsolder.

Butwhatif,forexample,youwantedtobuildanArduinoprojectthatyoucouldwear?Youcan’tusestiffwiresandhardsolderifyouwantsomethingtobendlikefabricandbecomfortabletowear.Luckily,conductivemetalscanbemadeintothread,whichmeansyoucansewacircuitwithaneedleand(conductive)thread.It’scalledmakingasoftcircuit.Andthere’saparticulartypeofArduinoboardthathasbeenbuilttomakeiteasytosewamicrocontrollerintoyourproject:theLilypadArduinoUSB!

Inthisadventureyou’regoingtocreateahoodiewithanArduinoandLEDsembeddedinitssleeve.TheLEDswilldisplayasecretmessagethatyouprogramintoyourLilypadArduinoUSB.ThesecretmessageisstoredontheLilypadArduinoUSBusingarrays,sobeforeyoustartwritingthecodeforthisadventure’sproject,Iremindyouhowarraysworkandshowyouhowtopushthemtoaseconddimension.

WhatYouNeedYouneedthecomponentsshowninFigure8-1forthefirstpartofthisadventure.

AcomputerALilypadArduinoUSBAUSBMicrocable10alligatorclips5LilypadLEDs(or5LEDsand568Ωor100ΩresistorsifnotusingLilypadLEDs)

Figure8-1Theelectroniccomponentsyouneedforthefirstpartofthisadventure

IntroducingtheLilypadArduinoUSBTheLilypadArduinoUSBisamemberofafamilyofLilypadArduinos.AlthoughyoucoulduseanyoftheLilypadArduinos,theLilypadArduinoUSBshowninFigure8-2hassomefeaturesthatmakeitabitnicertouse,suchasnotneedingasecondboardtouploadsketches.ButbecausetheyareallArduinos,yourcoderemainsthesame,sothecodeyouwriteherewillstillworkonaLilypadArduino,LilypadArduinoSimpleorLilypadArduinoSimpleSnap.

Figure8-2TheLilypadArduinoUSB

TheLilypadArduinoUSBhasthesamemicrocontrollerchipastheArduinoLeonardo.ThatmeansyoucanturnitintoamouseorkeyboardjustlikeyoucanwithanArduinoLeonardo,butitalsomeansitiseasiertoprogramthantheotherLilypadArduinos.TheLilypadArduinoUSBhasaUSBMicroconnectoronit—thesameconnectorthatisontheArduinoLeonardo.ProgrammingtheLilypadArduinoUSBisjustlikeprogramminganyoftheotherArduinoboardsyouhaveusedsofar:ConnecttheboardtotheUSBcableandthenconnecttheUSBcabletothecomputer.

TheothertypesofLilypadArduinodon’thaveaUSBMicroconnectoronthem.Insteadtheyhavesixpinsonthetopoftheboard.ThesepinsconnecttoaFTDIboard(seeFigure8-3),whichhasaUSBconnectoronit.Toprogramthoseboards,youfirstconnecttheFTDIboardtotheLilypadArduino,thenconnecttheUSBcabletotheFTDIboardandthenconnecttheUSBcabletothecomputer.SoifyoualreadyhaveaLilypadArduinoorcan’tfindaLilypadArduinoUSB,don’tworry!YoucanstilluseadifferentLilypad

Arduinoboard;justmakesureyoualsogetanFTDIprogrammingboard.

FTDIstandsforFutureTechnologyDevicesInternational,acompanythatmakesachipthatwasusedinmostArduinoboards.AnFTDIchiptranslatestheelectricalsignalssentbythecomputeroveraUSBcableintosignalstheArduinocanunderstand.TheArduinoUnousesachipsimilartotheFTDIchiptodothistranslationforthemicrocontrollerchip.ItcomesalreadyincludedontheArduinoUno’sboard.

TheLilypadArduinodoesn’thavethisextrachiponitsboard,soyouhavetoconnecttheLilypadArduinotoanFTDIboardthathasthechiponitwheneveryouwanttouploadnewsketches.TheLilypadArduinoUSBhasadifferentmicrocontrollerchipthantheArduinoUnoorLilypadArduino.ItschipcanhandlethetranslationfromtheUSBsignalonitsownwithoutasecondchip,soyoudon’tneedtouseanFTDIboard.

IfyouareinterestedinthedesigndetailsthatmaketheArduinoboardsdifferentfromeachother,checkoutSparkfun’scomparisonguideathttps://learn.sparkfun.com/tutorials/arduino-comparison-guide/introduction.

Figure8-3AnFTDIprogrammingboard,whichyouneedifyouareusingatypeofLilypadArduinootherthanaLilypadArduinoUSB

BlinkingfromaLilypadArduinoThefirstandvitallyimportantdifferencebetweentheArduinoUnoandLeonardoandtheLilypadArduinoisthatithasanONswitch!Theboardwon’tautomaticallyturnonifyougiveitpower,whichcanbeconfusingandfrustratingifyoudon’tknowabouttheswitch.Youmighteventhinkyourboardisbroken!Butdon’tfret.Theswitchisonthetopoftheboard,ontheoppositesideofthemicrocontrollerchipfromtheresetbutton.Figure8-4showswhereitis.

Figure8-4TheArduinoLilypadArduinoUSBONswitch

OneofthethingsthattheLilypadArduinoUSBcandothatotherboardscan’tdoischargeabattery.Thisisconvenientforwearableprojectsastheyalmostalwaysneedtobebatterypowered.Theswitchhastwopositions:ONandCHG.CHGisforchargingabatteryfromtheUSBcable.Youcan’tchargethebatteryandturnonthemicrocontrolleratthesametime.Youwillfindoutmoreabouthowtopowertheboardwithbatterieslater,whenyoubuildyourhoodie.

WheneveryoustartusinganewmicrocontrollerorArduinoboard,it’salwaysgoodtobeginwitha“HelloWorld”programthatdemonstratesthatyourboardisworkingcorrectlyandyouknowhowtoprogramit.YoufirstdidthiswithyourArduinoUnoinAdventure1.ForArduino,theBlinksketchisthe“HelloWorld”program.

OpentheBlinksketchbylaunchingtheArduinoIDEandgoingtoFile⇒Examples⇒01.Basics⇒Blink.Youdon’tneedtochangeanyofthecodeandcanimmediatelyuploadittotheboard.

Touploadit,youneedtoconnecttheboardtoyourcomputerandthentelltheArduinoIDEwhichboardyouareusing.GotoTools⇒BoardandselectLilypadArduinoUSBfromthelist,asshowninFigure8-5.ThenclicktheUploadbutton.

Figure8-5SelectLilypadArduinoUSBfromthelistofboards

AlightontheLilypadArduinoUSBstartsblinking,turningonforonesecondthenoffforonesecond.

CHALLENGE

NewArduinoboardsoftencomewithBlinkalreadyrunningonthem,soyourboardmightalreadyblinkitsLEDonandoffonPin13foronesecondattime.ChangethetimingintheBlinksketchsothattheLEDisoffforonlyhalfasecondinsteadofafullsecond.UploadittotheboardandmakesuretheLEDnowblinksaccordingtothenewsketch.

PrototypingSoftCircuitsNowthatyouknowhowtouploadasketchtoyourLilypadArduinoUSB,youcanstartconnectingsensorsandactuators.Thepuzzlingthingishowareyousupposedtodothat?TheLilypaddoesn’thavepinsthatyoucanplugjumperwiresinto.Ithasbigpadswithholesthatarelargeenoughtoallowyoutosewconductivethreadeasilytocreatesoftcircuits,butyoudon’twanttoseweverycircuit.Thattakesalotoftime.Sohowdoyouprototypewithsoftcircuits?Theanswerisalligatorclips(sometimesalsocalledcrocodileclips).

Asensorisadevicethatdetectssomethingintherealworldsuchaslight,soundormovementandtranslatesitintoanelectricalsignal.Examplesincludepotentiometersandlight-dependentresistors.

Anactuatorisadevicethattranslatesanelectricalsignalintoareal-worldactionsuchaslight,soundormovement.Examplesincludemotors,lightsandspeakers.

Softcircuitsarecircuitsbuiltwithflexiblematerialslikeconductivethreadandfabric.Theyareoftenusedinprojectsthataregoingtobeworn.

Alligatorclips,showninFigure8-6,arewireswithspring-loadedclipsthatresemblethejawsofanalligator.YouattachoneendoftheclipontotheLilypadArduinoUSBpadandtheothertothenextpartofthecircuit,suchasanLED.

Figure8-6Insteadofjumperwirestoconnectcomponents,usealligatorclipswhenprototypingsoftcircuits.

Alligatorclipsarewireswithspring-loadedclipsthatresemblethejawsofanalligator.Theyareusefulforprototypingsoftcircuitsorconnectingcomponentsthatdon’tusejumperwires.

TheLilypadArduinoUSBoperatesatalowervoltagethantheArduinoUnoandLeonardo.WhenyousetapintoHIGH,itoutputs3.3Vinsteadof5V.Youdon’thavetoworryaboutwhyituses3.3Vinsteadof5V,butitdoesmeanthatyourLEDdoesn’tneedacurrent-limitingresistorwithashigharesistancevalue.Youcanusearesistorthat’sanywherefrom68to100Ω.

YoucanalsobuyLilypadLEDsliketheonesinFigure8-7foryoursoftcircuitprojects.TheseareLEDsonpurpleboards(thatmatchtheLilypadArduinoboards),andtheyalreadyhavecurrent-limitingresistorsontheboardwiththem.Asabonus,youdon’thavetosewasmanycomponents!

Figure8-7LilypadLEDsaresewableLEDsthatalreadyhavecurrent-limitingresistors.

CHALLENGE

UsealligatorclipstobuildacircuitwithyourLilypadArduinoUSBandanLED.IfyouhavearegularLED,besuretouseacurrent-limitingresistorthatiseither68or100Ωaswell;otherwise,youcanuseaLilypadLED.

ChooseoneofthepadstoconnecttoyourLEDcircuit.Notethatyoudon’thaveasmanytochoosefromasyoudowithotherArduinoboards.Youroptionsfordigitalpinsare2,3,9,1011.ChooseapinandthenmodifytheBlinksketchtouseyourchosenpininsteadofPin13.UploadyoursketchandblinkyourLED!

GettingCleverwithArraysInAdventure5,youwerefirstintroducedtoarraysforstoringalistofvalueswithoutneedingtocreateanewvariableforeachone.Tocreatealistofints,createavariablethatisthedatatypeint[]andthenlistthenumbersinside{},asshowninFigure8-8.

Figure8-8Alistofintegers,alsocalledaone-dimensionalarray

Listsareone-dimensionalarrays,butarrayscanhavemorethanonedimension.Theycanhaveanynumberofdimensionsyoulike,butitcanbedifficulttopicturesomethingwithmorethanthreedimensions.Two-dimensionalarraysaresomethingyouprobablyarealreadyusedto—theyaredataarrangedinrowsandcolumnslikeaspreadsheet.Figure8-9showsonewayyoucanpictureatwo-dimensionalarray.

Atwo-dimensionalarrayisdatastoredinrowsandcolumnslikeinaspreadsheet.

Figure8-9Atwo-dimensionalarrayofintegersstoredinrowsandcolumns

Youwillbeusingtwo-dimensionalarraystostorethemessagesthatyourhoodiewilldisplay.Eachletterofyourmessagewillbeanarray.PictureanLEDsignatabusstoportrainstationthatdisplayslettersandnumbers.Youcanthinkofeachcharacterastakinguparectangleofspace—eachletterornumberhasawidthandheight.Withinthatrectanglethelightsareturnedoninapatterntoshowthatletterornumber.ThoserectanglesofLEDsforeachletterornumberaretwodimensionalarrays.

Tocreateatwo-dimensionalarrayrequiresalittlemoreworkthancreatingaone-dimensionalarray.Inaone-dimensionalarray,youdon’thavetosayhowmanyitemsareinyourlist.Youcanjustlistthembetweenthe{andthe},andtheArduinoIDEcountsthemforyou.Whencreatingatwo-dimensionalarray,however,youhavetocounttheitemsyourself.

ThefollowingcodecreatesavariablecalledtwoDArraythathasthreecolumnsandtworows:inttwoDArray[2][3]={{1,2,3},

{4,5,6}};

Youmightwanttostorethenumberofcolumnsandrowsinvariablesasitisusefulinformationtorefertolater.Ifyouwanttodothis,youneedtoaddconstinfrontofthevariables.Thatmeansthevariable’svaluewon’teverchange.constnumRows=2;

constnumCols=3;

inttwoDArray[numRows][numCols]={{1,2,3},

{4,5,6}};

Itmightnotyetbeclearwhyyouwouldeverwanttousetwo-dimensionalarrays,solet’s

buildacircuitthatusesthem.BuildthecircuitinFigure8-10withanLEDattachedtoPins2,3,9,10and11.StartbyconnectingeachpintothepositivesideofoneoftheLilypadLEDs.ThenconnectallthenegativesidesoftheLilypadLEDstoeachother.ConnectthenegativesideoftheLEDconnectedtoPin2totheGNDpadoftheLilypadArduinoUSB.

Figure8-10CircuitforanarrayofLEDs

Ifyoudon’thaveLilypadLEDs,replacethemwithcurrent-limitingresistorsthatare68or100ΩandnormalLEDs.

You’renowgoingtoanimatetheLEDsandstoreeachframeoftheanimationinatwo-dimensionalarray.StartbyopeningtheArduinoIDEandcreatinganewsketch.Createanemptysetup()andloop():voidsetup(){

}

voidloop(){

}

Createtwovariablesthatholdthenumberofrowsandcolumnsinthearrayatthetopofthesketch.ThearrayhasonecolumnforeachLED(fivecolumns)andonerowforeachframeoftheanimation.Thesimpleanimationfortheexamplehasnineframes(ninerows):constintnumLEDs=5;

constintnumFrames=9;

NextcreatethearraythatholdseachofthepinnumbersthathaveLEDs:intledPins[]={

2,3,9,10,11};

Thentypeoutthetwo-dimensionalarrayoftheanimation:intframes[numFrames][numLEDs]=

{

{1,0,0,0,0},

{0,1,0,0,0},

{0,0,1,0,0},

{0,0,0,1,0},

{0,0,0,0,1},

{0,0,0,1,0},

{0,0,1,0,0},

{0,1,0,0,0},

{1,0,0,0,0}};

Addthefollowinglinesofcodeinsidesetup()tosetthepinmodeforeachLEDpin:inti;

for(inti=0;i<numLEDs;i++){

pinMode(ledPins[i],OUTPUT);

Insideloop()iswhereyoustarttoseeunfamiliarcode!Addthefollowingcodetoyoursketch,andthenyoucangooveritinmoredetail://variablestokeeptrackofcurrentframeandLED

intframe;

intled;

for(frame=0;frame<numFrames;frame++){

//iteratethrougheachframestoredinarow

for(led=0;led<numLEDs;led++){

//turnonorofftheeachLEDintheframe

digitalWrite(ledPins[led],frames[frame][led]);

}

delay(300);//pausebetweeneachframe

}

Youhaveusedforloopsbefore,togothrougheachiteminalistonebyone.Becausetherearetwodimensionstotheframesarray(youcanthinkofitasalistoflists),twoforloopsareneeded.

Thefirstforloopgoesthrougheachrow,whichholdsaframeofdatadescribingwhatalltheLEDsshoulddo.ThesecondforloopgoesthroughthatframeandsetstheLEDtobeonoroff.AfterthesecondforloophasturnedeachoftheLEDsonoroff,thesketch

pausesbeforecontinuingtothenextframe.Ifitdidn’tdothis,theanimationwouldbetoofasttosee!Figure8-11showshowthearrayisiteratedover,rowbyrow.

Figure8-11Iteratingoverframesofananimationstoredinatwo-dimensionalarray

Thefollowingcodeisthefullsketch.Buildthecircuitanduploadthesketchtoseetheanimationinmotion:constintnumLEDs=5;

constintnumFrames=9;

//pinsthathaveLEDs

intledPins[]={

2,3,9,10,11};

//framesoftheanimation

intframes[numFrames][numLEDs]=

{

{1,0,0,0,0},

{0,1,0,0,0},

{0,0,1,0,0},

{0,0,0,1,0},

{0,0,0,0,1},

{0,0,0,1,0},

{0,0,1,0,0},

{0,1,0,0,0},

{1,0,0,0,0}};

voidsetup()

{

//setpinmodestoOUTPUT

inti;

for(inti=0;i<numLEDs;i++){

pinMode(ledPins[i],OUTPUT);

}

}

voidloop()

{

//variablestokeeptrackofcurrentframeandLED

intframe;

intled;

for(frame=0;frame<numFrames;frame++){

//iteratethrougheachframestoredinarow

for(led=0;led<numLEDs;led++){

//turnonorofftheeachLEDintheframe

digitalWrite(ledPins[led],frames[frame][led]);

}

delay(300);//pausebetweeneachframe

}

}

PassingDataBetweenFunctionsIfyouwanttodootherthingsinloop()besidesrunningtheanimation,it’susefultoputtheanimationcodeintoitsownfunction.Thenextexampleshowsyouhowdothat.

CreateafunctioncalleddisplayAnimation()andcutandpastetheanimationcodefromloop()intothefunction:voiddisplayAnimation(){

//variablestokeeptrackofcurrentframeandLED

intframe;

intled;

for(frame=0;frame<numFrames;frame++){

//iteratethrougheachframestoredinarow

for(led=0;led<numLEDs;led++){

//turnonorofftheeachLEDintheframe

digitalWrite(ledPins[led],frames[led][frame]);

}

delay(300);//pausebetweeneachframe

}

}

Rememberthatyounowneedtocallyournewfunctionfromloop()oritwillneverruntheanimation.ThenewfunctiondisplayAnimation()shouldbeafterloop()andloop()shouldlooklikethefollowingvoidloop()

{

displayAnimation();

}

Nowthatthecodecontrollingtheanimationisnicelycontainedwithinonefunction,youcantakeadvantageofhowfunctionswork.Youcanpassdatatothefunctionandthenhavethefunctionchangewhatitdoesaccordingtothatdata.

Inordertopassdata,youneedtocreateanargument.Thisisdoneinthesamelineofcodewhereyougivethefunctionaname.Youalsogiveyourargumentanameandsaywhatdatatypeitwillhave.

Changeyourfunctiontothefollowing:voiddisplayAnimation(intanimationSpeed){

ThedisplayAnimation()functionnowhasoneargumentthatisanint;thisisanimationSpeed.ThefunctionnowneedstodosomethingwithanimationSpeed.Itwillcontrolthelengthoftimetheanimationpausesbetweeneachframe.Usethisvariabletosetthedelay()aftereachframe.

Changethelineofcodethatsetsthedelayinthefunctiontothefollowing:delay(animationSpeed);//pausebetweeneachframe

NowyoucancallthefunctiondisplayAnimation()withdifferentvaluesfortheargument,toplaytheanimationatdifferentspeeds!Thefollowingcodeisthefullsketch.UploadittoyourLilypadArduinoUSBwithfiveLilypadLEDsconnectedandwatchthe

animationdescribedbythetwo-dimensionalarray://constmeansthevaluewon’tchange

constintnumLEDs=5;

constintnumFrames=9;

//pinsthathaveLEDs

intledPins[]={

2,3,9,10,11};

//framesoftheanimation

intframes[numFrames][numLEDs]=

{

{1,0,0,0,0},

{0,1,0,0,0},

{0,0,1,0,0},

{0,0,0,1,0},

{0,0,0,0,1},

{0,0,0,1,0},

{0,0,1,0,0},

{0,1,0,0,0},

{1,0,0,0,0}};

voidsetup()

{

//setpinmodestoOUTPUT

inti;

for(inti=0;i<numLEDs;i++){

pinMode(ledPins[i],OUTPUT);

}

}

voidloop()

{

displayAnimation(100);

displayAnimation(500);

displayAnimation(1000);

}

voiddisplayAnimation(intanimationSpeed){

//variablestokeeptrackofcurrentframeandLED

intframe;

intled;

for(frame=0;frame<numFrames;frame++){

//iteratethrougheachframestoredinarow

for(led=0;led<numLEDs;led++){

//turnonorofftheeachLEDintheframe

digitalWrite(ledPins[led],frames[frame][led]);

}

delay(animationSpeed);//pausebetweeneachframe

}

}

CHALLENGE

BuildthecircuitfortheLEDanimationshowninthesectionheaded“PassingDataBetweenFunctions.”Modifythecodeinthesketchtouseaforlooptocyclethroughspeedsfortheanimationfrom50to500.

Rememberthatyoucanincrementinstepshigherthanone,forexamplebycreatingthefollowingforloop:

inti;

for(i=0;i<100;i+=5){

}

BuildingaPOVHoodieHaveyoueverwavedasparkleraroundandnoticedthatitseemedtoleaveatrailoflight?Ormaybeyou’veseentoyswithasetofLEDsthatdisplayawordorimagewhenyoumovethemquickly.Bothareexamplesofpersistenceofvision(POV)whereyoureyesandbrainkeepseeingalightpathafterthelightsourceismovedorturnedoff.Inthecaseofthesparkler,theglowingsparklermovesbutyourbrainstillseeswhereitusedtobe,soitlookslikeit’sleavingatrail.Withthetoys,theLEDsareblinkingonandoffquicklyinapattern.Yourbrainputsallthedifferentpatternstogetherwhenthetoyismovedandinterpretsthepatternsasawordorimage.

Excitingly,youcanmakeyourownPOVdisplaywiththeLilypadArduinoUSBand,becauseyouareusingaLilypad,youcansewthecircuitintoclothesandwearit.YoucanthenprogramyourLilypadtodisplayasecretmessagethatcanbeseenbytakingalongexposurephotograph(seeFigure8-12).Sewingthecircuitontheshoulderofahoodieworkswell,butyoucansewitonanypieceofclothing!

Figure8-12Persistence-of-visionhoodie

WhatYouNeedYouneedthefollowingitemstobuildaPOVhoodie.Figure8-13showstheelectroniccomponentsthatyouneed:

AcomputerALilypadArduinoUSBAUSBmicrocableAbreadboard14alligatorclips7LilypadLEDs(or7LEDsand768Ωor100ΩresistorsifnotusingLilypadLEDs)Alithiumionpolymer(LiPo)batterySomenormalsewingthreadSomeconductivethreadAhoodieAsewingneedleScissorsSomewhitePVAgluePliers(ifnotusingLilypadLEDs)

Figure8-13TheelectroniccomponentsyouneedforthePOVhoodie

UnderstandingTheCircuitThecircuitforthePOVhoodieissimilartotheLEDanimationcircuityoumadeearlierinthisadventure.TheonlychangeisthatyouusesevenLEDsinsteadoffive.Figure8-14showsthecircuitschematicforthePOVhoodie.

Figure8-14CircuitschematicforthePOVhoodie

PrototypingwithAlligatorClipsThePOVhoodieisasoftcircuit,soyoushouldprototypethecircuitwithalligatorclipsbecausetheLilypadArduinoUSBandLilypadLEDsdon’tfitintoabreadboard.BuildthecircuitshowninFigure8-15.

Figure8-15Prototypingthecircuitwithalligatorclips

StartbyconnectingeachpintothepositivesideofoneoftheLilypadLEDs.ThenconnectallthenegativesidesoftheLilypadLEDstoeachother.ConnectthenegativesideoftheLEDconnectedtoPin2totheGNDpadoftheLilypadArduinoUSB.

Ifyoudon’thaveLilypadLEDs,replacethemwithcurrent-limitingresistorsandnormalLEDs.

ChargingtheBatteryTheLilypadArduinoUSBincludesaconnectorforarechargeablelithiumionpolymer

(LiPo)batteryandevenhasachargerbuiltin.LiPobatteriesareflat,silverbatteries.Youdon’tneedabigbatteryforthisproject.Batteriesaremeasuredinmilliamp-hours(mAh),whichisameasureofhowmuchcurrenttheycanoutputforhowlong.A500mAhbatteryprovidesagoodbalance—it’snottoobiganddoesn’tneedtobechargedtoofrequently—butyoucanusewhateversizebatteryyoucanbuyeasily.

Tochargethebattery,connectittotheLilypadArduinoUSBandconnecttheLilypadtoapowersourcesuchasacomputerwithaUSBcable.MakesuretheswitchontheLilypadboardisintheCHGposition.TheLEDaboveCHGontheboardlightsupwhenthebatteryischarging;thebatterystopschargingautomaticallywhenit’sfullycharged.

LiPobatteriescanbedangerousifyoudon’ttakecareofthemproperly.Neverleavethemontheirownwhilethey’recharging!It’salsobesttobuythemfromatrustedmanufacturerlikeAdafruitorSparkfun,oroneoftheirdistributors.OnlybuyLiPosthathavebuilt-inprotectioncircuitry,andneveruseabatterythatlooksswollenordamaged.AdafruithasaniceguideonhowtoworkwithLiPobatteriesathttps://learn.adafruit.com/li-ion-and-lipoly-batteries.

WritingtheCodeThecodefordisplayingthePOVmessageissimilartothecodefortheLEDanimationearlierinthisadventure.TheframesfortheLEDsarestoredintwo-dimensionalarrays:oneforeachletterandoneforaspace.Becausetherearesomanyarrays,tohelporganisethecodetheyareallstoredinaheader(.h)file.Thecodeisavailableatwww.wiley.com/go/adventuresinarduino.

OpenthedownloadedsketchintheArduinoIDE.Thesketchshouldhavetwotabs:onenamedpov_hoodieandtheotheralphabet.h.

Clickthepov_hoodietab.Changethemessageintheboldlineofcodeinloop()towhatyouwanttobewrittenonthehoodie,anduploadittoyourLilypadArduinoUSB.Yourmessagecanonlyconsistofuppercaselettersandspaces.voidloop()

{

Stringmessage="HELLO";//putmessageinallcapshere

printText(message);

}

Waveyourcircuitintheair(adarkroomandafriendtomovewiththecircuitmakesthiseasier),ortakealong-exposurephototoseethemessageasshowninFigure8-16.

Figure8-16Persistenceofvisionmessagecapturedwithalong-exposurephotograph

DIGGINGINTOTHECODE

OpenthesketchyoujustdownloadedintheArduinoIDE,andclickthealphabet.htabtoseethecodeintheheaderfile.

ThefollowingisthecodefortheletterA.Ifyouturnyourheadsideways,youmightbeabletoseetheshapeoftheletterAwrittenoutin1s:

intA[numFrames][numLEDs]={

{1,1,1,1,1,1,0},

{0,0,1,0,0,0,1},

{0,0,1,0,0,0,1},

{0,1,1,0,0,1,1},

{1,1,1,1,1,1,0}};

Inthemainsketch,theheaderfiledescribingallthelettersisimportedattheverytopofthefile:

#include"alphabet.h"

ThentherearethreevariablesdescribinghowlongtheLEDsareturnedoffbetweenletters,howlongtheyareonwhendisplayingaframeofaletterandwhatpinshaveLEDs.BecausetheLilypadArduinoUSBonlyhasfivedigitalpins,twoanalogpinsarealsoused:

intletterSpace=6;//timeLEDsoffbetweenletters

intdotTime=3;//timeLEDsareon

intledPins[]={

2,3,9,10,11,A2,A3};

Insidesetup(),eachpinMode()issettobeOUTPUTandserialcommunicationisstarted.TheserialcommunicationisusedfordebuggingtoseewhatisbeingoutputintheSerialMonitor:

//setpinmodestoOUTPUT

inti;

for(inti=0;i<numLEDs;i++){

pinMode(ledPins[i],OUTPUT);

}

Serial.begin(9600);

Theloop()iskeptquitesimpleasmostoftheworkisdoneinotherfunctions.ThemessagetobedisplayedisstoredinmessageandthensenttothefunctionprintText()asanargument.Becausetheheaderfileonlydescribeshowtodisplaycapitalletters,themessageneedstobewrittenonlyincapitallettersorspaces—thereshouldbenolowercaselettersorpunctuation:

Stringmessage="ABCD";//putmessageinallcapshere

printText(message);

ThefunctionprintText()isalongone,butitisjustdoingasimpletaskmanytimes.Itreadsinthemessage,letterbyletter,andthentellsthefunctionprintLetter()todisplaythatletterinthemessage.ThefollowingcodeisforonlyA,BandC,butyoucangettheideaforhowtherestofthealphabetworks:

for(inti=0;i<text.length();i++)

{

switch(text[i])

{

case'A':

printLetter(A);

break;

case'B':

printLetter(B);

break;

case'C':

printLetter(C);

break;

ThefunctionprintLetter()isjustlikethedisplayAnimation()functionyouwroteearlier.Itgoesframebyframethroughtheletterthatisbeingdisplayed.ItalsoprintswhatitisbeingsenttotheLEDstotheSerialMonitortohelpshowwhatisgoingon.Ithasanextraforloopattheendofthefunctiontopausebetweeneachletter;otherwise,itwouldbehardtoreadtheindividuallettersandtheywouldallblurtogether:

intframe;

intled;

//printletter

for(frame=0;frame<numFrames;frame++){

for(led=0;led<numLEDs;led++){

digitalWrite(ledPins[led],letter[frame][led]);

Serial.print(letter[frame][led]);

}

Serial.println();

//delaybetweeneachcolumndisplayed

delay(dotTime);

}

Serial.println("-------");

//printspaceafterletter

for(led=0;led<numLEDs;led++){

digitalWrite(ledPins[led],0);

}

//delayforspacebetweenletters

delay(letterSpace);

MakingthePOVHoodieAfteryouhavebuilttheprototypecircuitwithyouralligatorclipsanduploadedthecodetotestthatitallworks,youarereadytostartsewing!Usingconductivethread,youaregoingtostitchtheLilypadArduinoUSBpadstoeachoftheLEDs.Rememberthatconductivethreadisjustlikewire,butitdoesn’thavetheinsulatingplasticprotectingit.Thatmeansifanypiecesofthreadtoucheachother,theywillconductelectricitybetweenthemandmayshortyourcircuit.Useaseparatepieceofthreadforeachconnectionandmakesuretheydon’taccidentallytouchanotherpartofthecircuit.

MakingSewableLEDsIfyoudon’thaveLilypadLEDs,youcanstillusetheLEDsyouwoulduseinabreadboard.Usingpliers,twistthelegsoftheLEDsandresistorsintoloopsthatyoucansewthrough.YoucantwistthelongandshortlegsoftheLEDsintotwodifferentshapestokeeptrackofwhichisthepositiveandwhichisthenegative.Iliketotwistthepositiveintoacircleandthenegativeintoasquare(becauseitremindsmeofanegativesign)asshowninFigure8-17,butyoucanmakeanyshapesthathelpyoukeeptrackofthelegs.

Figure8-17Bendingthelegsofcomponentstomakethemsewable

SewingtheElectronicsSewthecircuitbygoingthroughthefollowingsteps:

1. StartbydecidingwhereyouwanttoplaceyourLEDsontheupperrightsleeveofyourhoodie.YoumaywanttomarkthelocationsoftheLEDswithpinsortailor’schalk.

2. StartwiththebottomLED.Usingconductivethread,stitchPin9tothepositivesideoftheLED.KeepthestitchesfirmagainstthefabricofthehoodieandstitchthepadsoftheLilypadArduinoUSBandtheLilypadLEDaboutfivetimestosecurethemtothefabric.Knotandcutthethread.SeeFigure8-18forguidance.

3. Alternatively,ifyouareusingregularLEDsandresistors,stitchtheArduinopadtotheLEDandthenuseaseparatepieceofconductivethreadtostitchtheLEDtotheresistor.

4. Withaseparatepieceofconductivethread,stitchPin10tothepositivesideofthenextLEDabovetheoneyoujustsewed.Again,firmlystitchthepadstothefabricandthenknotandcutthethread.

5. ContinuewitheachoftheremainingLEDs.Takecarethatthestitchedthreadsnevertoucheachother(seeFigure8-19).

6. ThenegativesidesoftheLEDs(orresistorsifyouarenotusingLilypadLEDs)canalltoucheachother,sotheycanbesewnwithasinglepieceofthread.StartatthenegativepadoftheLilypadArduinoUSBandthenstitchthebottomLED.AftersecuringthenegativepadoftheLED,continuestitchinguptothenextLED.

7. Repeatstep6,sewingthenegativepadofthenextLEDuntilyouhavesewnonalltheLEDsasinFigure8-20.

8. SecureeachoftheknotswithalittlewhitePVAglue.Theconductivethreadcansometimesunknotitselfovertime,sothegluehelpstopreventthis.

9. Usingnormalthread,stitcharoundthebatterytosecureittothehoodie.

Figure8-18FirstconnectionsforsewingtheLilypadcircuit

Figure8-19ContinuingtosewtheLEDsintothecircuit

Figure8-20ThesewnPOVcircuit

YoumightnotwanttosewyourLilypadArduinoUSBdirectlyontoyourhoodie,especiallyifyouwanttousethesameboardinmultipleprojects.TheLilypadArduinoSimpleSnap(http://arduino.cc/en/Main/ArduinoLilyPadSimpleSnap)comeswithfemalesnapssolderedtoeachofthepads.Youcanthensewthematchingmalesideofthesnapsintothehoodieusingconductivethread.Becausethesnapsaremetal,theyconductelectricity,butthesnapsletyouremovetheboardfromthehoodiewithoutharmingthehoodie.

YoucanmodifyyourLilypadArduinoUSBtoworkthesamewaybysolderingsnapsontothepadsyourself.Youcanfindmetalsnapsatanysewingorcraftstore.

FurtherAdventureswiththeLilypadIfyouwouldliketolearnmoreabouttheLilypadArduinoUSB,visititspageontheArduinowebsiteathttp://arduino.cc/en/Guide/ArduinoLilyPadUSB.

YoucanalsolearnmoreaboutusingtheLilypadandfindmoreprojectsathttp://lilypadarduino.org.

Therearealotbooksaboutsoftcircuitsforyoutochoosefrom.Herearejustafew:

FashioningTechnologybySyuziPakhchyan(MakerMedia,2008)Make:WearableElectronicsbyKateHartman(MakerMedia,2014)SwitchCraftbyAlisonLewisandFang-YuLin(PotterCraft,2008)SewElectricbyLeahBuechley,KanjunQiandSonadeBoer(HLTPress,2013)Make:WearableElectronicsbyKateHartman(MakerMedia,Inc.,2014)

ArduinoCommandQuickReferenceTable

Command Description

int[][] Indicatesthatthevariablewillbeatwo-dimensionalarrayofvariablesstoredinrowsandcolumns.

const Indicatesthatthevariablewillnotchangeitsvalue.

AchievementUnlocked:BrightlightofArduinofashionandmanipulatorofmultipledimensions!

IntheNextAdventureInthenextadventure,youputallyournewskillstogethertocreateapinball-inspiredgame!

YOU’VECOMEAlongway,andnowyou’vereachedyourfinaladventure—thebiggestyet!Inthisadventure,youaregoingtocombinedigitalinput,digitaloutput,analogueinputandanalogueoutputtocreateamarblemazegameliketheoneinFigure9-1.Inspiredbyretropinballmachines,yourgameknowswhenyou’vescoredpointsandtellsyouifyou’veachievedanewhighscore.Itcountsdowntowhenthenextgamebeginsandkeepstrackofthetimeremaininginthegame.Itevenhasitsownsoundeffects!

Figure9-1Acompletedbigadventuremarblemazegame

Thegamebringstogetheralotofthedifferentskillsyou’velearnedfromtheearlier

adventures,butthereareacoupleofotherthingsforyoutolearnbeforeyoucanbuildyourgame.Thefirstishowtouseapiezoasasensor.You’vealreadyusedapiezoasaspeakerbutitisamultitalentedcomponentandyoucanalsouseittosensevibrations,whichisavitalskillforyourmarblemazegame!

WhatYouNeedYouneedthefollowingitemsforyourmarblemazegame.TheelectroniccomponentsthatyouneedareshowninFigure9-2:

AcomputerAnArduinoUnoAUSBcableAbreadboardSomejumperwires6piezos61MΩresistor1redLED1yellowLED1greenLED3220Ωresistors1panelmountpush-to-makebutton1tactilepushbutton19Vbattery19VbatteryconnectorSomewireAmarbleAcardboardboxSomethickpaperorcardWhitePVAglueMaskingtapeorducttapePaintormarkersScissorsorautilityknifeAsolderingironSolder

Figure9-2Theelectroniccomponentsyouneedtobuildyourmazegame

PartOne:ScoringPointsInAdventure5youwereintroducedtopiezosasactuatorsthattranslateavaryingvoltageintoavibrationthatyoucanthenhearasasoundwave.Butthat’snotalltheycando!Piezosarecleverlittlecomponentsthatcanalsotranslatevibrationsintovaryingvoltage.

Inthisadventure,youusepiezostodetectwhichholeinthemazeyourmarblehasfallenthrough.Eachholeisworthadifferentnumberofpoints,sopartofyourgamedesignistomaketheholesthatarehardertoreachworthmorepoints.

SensingVibrationswithPiezosPiezoshavetheabilitytoproducevoltagespikesthatcoulddamageyourArduino,soyouneedareallybigresistortohelpprotectyourArduino.Aresistorvalueof100MΩ(that’s100millionOhms)istypicallyused.

Aspiezosoutputavaryingvoltage,youwillwanttomeasurenotjustLOWorHIGHvoltagesbutalsovoltagesinbetween.YouwillthereforewanttouseanAnalogPinandanalogRead()tomeasurethevoltage.

BuildthecircuitshowninFigure9-3:

1. Placetheredwireofthepiezoinanyoftheshort,middlerowsofthebreadboardandplacetheblackwireinoneofthelongoutsiderows.

2. Putonelegofa1MΩresistorinthesameshortrowastheredwireandtheotherleginthesamelongrowastheblackwire.

3. UseajumperwiretoconnecttherowwiththeredwireandresistorlegtoPinA0.4. Useanotherjumperwiretoconnecttherowwiththeblackwireandtheotherresistor

legtoGND.

Figure9-3Circuittouseapiezoasasensor

LaunchtheArduinoIDE.GotoFile ⇒ Examples ⇒ 06.SensorandopenthesketchKnock.UploadittoyourArduinoandopentheSerialMonitor.Tryoutthesketchbytappingonthepiezo.WatchwhathappenstotheLEDnexttoPin13andseewhatisprintedintheSerialMonitor.YoushouldseetheLEDturnonandoffwithyourknocksonthepiezo.

SettingaPointsThresholdYounowhavethebasicsofhowtoreadinavaluefromapiezo—butyouneedmorethanonepiezotomakeyourgamechallenging!Thenextstepistoaddfourmorepiezossothatyouhavefiveintotal.

OnthesamebreadboardwhereyouhaveonepiezoconnectedtoPinA0,setupfourmorepiezosinthesameway.ConnectthemtoPinsA1,A2,A3andA4asshowninFigure9-4.Ignorethelastpiezofornow(theoneconnectedtoPin9).

Figure9-4Circuitforfivepiezosassensorsandonepiezoasaspeaker

LaunchtheArduinoIDEandstartanewsketch.Beginbycreatinganemptysetup()andloop():voidsetup(){

}

voidloop(){

}

Becauseyouhavefivepiezostokeeptrackof,it’sbesttostorethemallinanarray.Atthetopofthesketch,addanarraythatstoresallthepinswiththepiezosassensorsandavariablethatstoreshowmanypiezosyouareusing:intpointsPins[]={

A0,A1,A2,A3,A4};

//numberofpiezosforpoints

intnumPointsPins=5;

Youdon’tneedtosetthepinmodeofAnalogPinswhenyouareusingthemasinputs,sotheonlylineofcodetoaddtoyoursetup()isforbeginningserialcommunication:Serial.begin(9600);

Insideloop(),readinthevalueofeachofthepiezos.Becausethepinsareallstoredinanarray,youcanuseaforloop.FornowyoujustprintthosevaluestotheSerialMonitor.

Addthefollowinglinesofcodetoyourloop,thenuploadittoyourArduinoUnoandopenSerialMonitorintheArduinoIDE://variablesforpins

inti;

for(i=0;i<numPointsPins;i++){

intcurrPinValue=analogRead(pointsPins[i]);

//printwhichpininarrayandvalue

Serial.print("Piezo:");

Serial.print(i);

Serial.println("Value:");

Serial.println(currPinValue);

}

Taponthepiezosandnotewhatvaluesarebeinggenerated.Dropthemarbleyouwilluseinyourmazegameontoapiezoandwatchthevalues.

Nowyouneedtochangeyoursketchsothatamessageisonlyprintedwhenapiezogoesaboveathresholdvalue.Inotherwords,amessageisonlyprintedwhenthepiezosaretriggeredwithastrongenoughforce.

Atthetopofyoursketchbeforesetup(),withyourothervariables,addavariabletosetthethresholdofwhenapiezoshouldtriggerscoringpoints.Setittoavaluethatmakessensefromyourtestswithyourmarble:intpiezoThreshold=800;

Insideofloop(),addanifstatement.Theifstatementcheckswhetherthecurrentpiezobeingreadhasgoneabovethethresholdthatyouset.Whenthecurrentgoesabovethethreshold,thepiezonumberandvalueareprintedtoSerialMonitor.inti;

for(i=0;i<numPointsPins;i++){

if(currPinValue>piezoThreshold){

//printwhichpininarrayandvalue

Serial.print("Piezo:");

Serial.print(i);

Serial.println("Value:");

Serial.println(currPinValue);

//pausesothatsamemarbledoesn’tscoretwice

delay(300);

}

}

Uploadthechangestoyoursketchandcheckthateachpiezoonlyprintsamessagewhenyoudropthemarbleonit.Hereisthesketchasitstands://variablesforpins

intpointsPins[]={

A0,A1,A2,A3,A4};

//numberofpiezosforpoints

intnumPointsPins=5;

//---setup---------------------------

//runsoncewhenboardfirstpowered

//orreset

voidsetup(){

//startserialcommunication

Serial.begin(9600);

}

//---loop----------------------------

//runscontinuouslyaftersetup()

voidloop(){

inti;

for(i=0;i<numPointsPins;i++){

intcurrPinValue=analogRead(pointsPins[i]);

//ifabovethethreshold

if(currPinValue>piezoThreshold){

//printpointsandnewscore

Serial.print("Piezo:");

Serial.print(i);

Serial.println("Value:");

Serial.print(currPinValue);

//pausesothatsamemarbledoesn’tscoretwice

delay(300);

}

}

}

AddingSoundEffectsNowit’stimetoseewhatthatsixthpiezoissupposedtodo!Intheprevioussectionyouworkedwiththefivepiezosthatareactingassensors;thesixthpiezoactsasaspeaker.InFigure9-4,thecircuitforthesixthpiezolooksjustlikethecircuitsfortheotherfivepiezos,whichmightbeconfusing.TheonlydifferenceisthatitisconnectedtoPin9insteadofanAnalogPin.

YouusePin9sothatyoucancalltone()tomakesoundthroughthepiezo.However,justbecausethepiezoisbeingusedasaspeaker,itdoesn’tpreventitfrompotentiallyproducingavoltagespikeasasensor.Ifthemarblehitsthespeakerpiezo,itcouldproduceavoltagespikethatcoulddamageyourArduinoUno.Soyouusethesameprotectioncircuitonthespeakerpiezo.

GoaheadandaddthelastpiezoonPin9asshowninFigure9-3.

Inyourcode,addavariableatthetopbeforesetup()tokeeptrackofthespeaker:intspeakerPin=9;

Rightafteryouhaveprintedyourmessagesintheforloopandbeforethedelay(),addthefollowinglinesofcodeinboldtoplayasoundwheneverapiezoistriggeredabovethethreshold://ifabovethethreshold

if(currPinValue>piezoThreshold){

//printpointsandnewscore

Serial.print("Piezo:");

Serial.print(i);

Serial.println("Value:");

Serial.print(currPinValue);

//playscoringmusic

tone(speakerPin,659,300);

delay(300);

//pausesothatsamemarbledoesn’tscoretwice

delay(300);

}

UploadyoursketchtoyourArduinoUnoandtestthatyouhearatonewheneverapiezoistriggered.

KeepingScoreNowthatyouhavefivepiezosthatsensewhenthemarbledropsonthemandanotherthatactsasaspeaker,youcanstartassigningpointvaluestoeachofthesensorsandkeeptrackofyourscore.

Firstyouneedtocreateanewvariabletostoreyourscore.Atthetopofyoursketch,withyourothervariables,addthefollowingline:intcurrentScore=0;

Insidetheifstatementintheforloopinloop(),youaregoingtodothreethings.Firstyoucreateavariablethatcalculateshowmanypointshavejustbeenscoredandthenaddsittocurrentscore.ThenyouprintthenumberofpointsthathavejustbeenscoredandthenewtotalcurrentscoretotheSerialMonitor:if(currPinValue>piezoThreshold){

//addpoints

intnewPoints=(i+1)*10;

currentScore+=newPoints;

//printpointsandnewscore

Serial.print("Score!");

Serial.print(newPoints);

Serial.println("points");

Serial.print("Currentscore:");

Serial.print(currentScore);

Serial.println("points");

//playscoringmusic

tone(speakerPin,659,300);

delay(300);

//pausesothatsamemarbledoesn’tscoretwice

delay(300);

}

Thenumberofpointsisdeterminedbyadding1tothepininthearraythatwastriggered(thevariablei)andthenmultiplyingthatnumberby10.Forexample,thepiezoonPinA3isitem3inthearray,sothescorefortriggeringthatpiezois(3+1)*10,or40points.

Thefollowingcodeisthefullsketchwiththechangesinbold.UploadittoyourArduinoUnoandopentheSerialMonitor.Checkthatthesoundeffectsandpointsmessagesallworkasyouwouldexpect://variablesforpins

intpointsPins[]={

A0,A1,A2,A3,A4};

intspeakerPin=9;

//numberofpiezosforpoints

intnumPointsPins=5;

//whenpointstriggered

intpiezoThreshold=800;

intcurrentScore=0;

voidsetup(){

//startserialcommunication

Serial.begin(9600);

}

voidloop(){

inti;

for(i=0;i<numPointsPins;i++){

intcurrPinValue=analogRead(pointsPins[i]);

//ifabovethethreshold

if(currPinValue>piezoThreshold){

//addpoints

intnewPoints=(i+1)*10;

currentScore+=newPoints;

//printpointsandnewscore

Serial.print("Score!");

Serial.print(newPoints);

Serial.println("points");

Serial.print("Currentscore:");

Serial.print(currentScore);

Serial.println("points");

//playscoringmusic

tone(speakerPin,659,300);

delay(300);

//pausesothatsamemarbledoesn’tscoretwice

delay(300);

}

}

}

Youcandownloadallthesketchesfromthecompanionsiteatwww.wiley.com/go/adventuresinarduino.

PartTwo:DesigningYourMazeGameAtlastyou’rereadytostartworkingonyourmaze!First,youneedtofindaboxthatyoucanturnintoyourgame.Theexactsizeisn’timportant—itjustneedstobebigenoughtoholdallthesensorsandtheArduinoUno,butit’sbestnottohaveaboxthat’ssobigthatyoucan’teasilyholditinyourhands.Aboxthatisapproximately10×13×3inches(26×33×8cm)workswell.

Ifyoucanonlyfindaboxthatistherightlengthandwidthbutistootall,usescissorsorautilityknifetomakeitshorter.Youmayneedhelpfromanadultifit’stoughtocut!

DrawingtheMazeWhenyouhaveyourboxready,makeasketchofwhatyouwantyourmazetolooklike.Hereareafewrulestokeepinmindwhenyoudothis(seeFigure9-5):

Makeyourgameintofivecolumnsanddecidewhereineachcolumnyouwillplacetheholes.Therewillonlybeonepiezoforeachcolumn,soyoucanonlyhaveoneholepercolumn.Decidehowmanypointsyouwanteachholetobeworth,withoneworth10points,oneworth20,oneworth30,oneworth40andoneworth50.Makethemostdifficultholeworththemostandtheeasiestoneworththeleast.It’simportanttoleaveanemptyspaceatthebottomofthemaze.Thisiswherethemarblerollsoutwhenyouhavescored.Youneedtoleaveenoughspacethatyoucaneasilyretrievethemarbleandplayagain.Reserveasectionintheupper-rightcornerforthreeLEDsandthebutton.Thesetellyouwhentostart,whenyourtimeisupandwhetheryouhaveachievedanewhighscore.LeaveenoughroomfortheLEDs,buttonandlabels.Approximately2×3inches(5×8cm)shouldbeenough.Decidewhereyouwillplacethemarbleatthestartofeachgame.

Figure9-5Guidelinesfordesigningyourmaze

Afteryouhavelaidoutwheretheholesandothercomponentswillbelocated,youarereadytodesignyourmaze!Drawthepathofyourmazeonapieceofpaper.Don’tlosethatpieceofpaper—you’llneeditlaterwhenyouactuallybuildthemaze.

DesigningtheGameCodeHere’showthemarblemazegameisplayed:

1. Theplayerpressesthestartbutton.TheredLEDlightsup,thentheyellowLEDandfinallythegreenLED.Thestartingmusicplaysandthegamestarts.Theplayerplacesthemarbleinthestartingpositiononthemaze.

2. Theplayertriestorollthemarblealongthemazeandintothedifferentholestoscorepoints.

3. Atoneplayswheneverpointsarescored.4. Eachtimetheplayerscores,themarblerollstothebottomofthebox.Theplayer

placesthemarblebackatthestartingpositionandtriestoscoreagain.5. Thestepsarerepeateduntilthetimerunsout.6. Iftheplayerhasjustachievedanewhighscore,atuneplaysandthegreenLED

blinks.Iftheydidn’tachieveanewhighscore,adifferenttuneplaysandtheredLEDblinks.

7. IftheArduinoUnoisresetorturnedoff,thehighscoreiscleared.Otherwiseplayerscanplaymoreroundsandtrytobeattheprevioushighscore.

Allofthesestepscanbebrokendownintofunctionsforthecode.Thenthosefunctionscanbecalledattherighttimeinthegame.Figure9-6showshowallthefunctionsinteractintheArduinosketchthatyouwillwritelater.

Figure9-6Howthecodeworkswhenagameisplayed

PrototypingtheCircuitYouhavealreadybuiltmostofthecircuitforthemazegame—youhavebuiltthecircuitforthefivesensorpiezosandthespeakerpiezo.TheremainingcomponentsarethethreeLEDsandbutton.Figure9-7showsthecircuitschematicforthefullmazegame.

Figure9-7Circuitschematicofthemazegame

Youshouldtestyourcircuitonabreadboardbeforebuildingyourfullmazegame—butyouknowthatbynow!Buildthecircuitnow(showninFigure9-8):

1. Startwiththepiezocircuitsthatyouhavealreadybuilt.2. AddthreeLEDstothebreadboard—onered,oneyellowandonegreen.Connectthe

negativelegstothelongrowconnectedtoGND.3. Placea220Ωcurrent-limitingresistorbeforeeachLED.4. UseajumperwiretoconnecttheresistorbeforetheredLEDtoPin6,theresistor

beforetheyellowLEDtoPin5andtheresistorbeforethegreenLEDtoPin4.5. Placeyourtactilepushbuttonacrossthegapinthemiddleoftheboard.Useajumper

wiretoconnectonesideofyourbuttontothelongrowconnectedtoGND.ConnecttheothersidetoPin7.

Figure9-8Mazegameprototypecircuitonabreadboard

PartThree:WritingtheCodeYou’reabouttowritethelongestArduinosketchofalltheadventures.Don’tworry—youareready!Youhaveseenallthedifferentpartsofthecodebefore.You’reabouttoputittogetherintoamorecomplexsketch,butthesketchisjustmadeupofsmallerchunksofcode.Youstartwiththepiezo-scoringsketchthatyouwroteearlierinthisadventureandaddnewfeatures,littlebylittle.Youshouldtestwhatyouhavewrittenafteryouaddeachnewfeature;I’lltellyouwhenyoushoulddothat.

StartingtheGameTheLEDsneedtoshowthecountdowntobeginwheneveranewgameisstarted.YoucanalsoprintserialmessagesthatshowextrainformationifyourArduinoUnoisconnectedtoyourcomputer.ThefirstlinesofcodearethevariablesfortheLEDpins.Atthetopofyoursketchaddthefollowinglines:intgreenLED=4;

intyellowLED=5;

intredLED=6;

Tohelporganiseyoursketch,youcreateafunctionthatperformsallthetasksthatneedtobedonewhenanewgamebegins.Addthefollowingcodetotheendofyoursketchafterloop():voidstartGame(){

//makesureallLEDsstartoff

digitalWrite(redLED,LOW);

digitalWrite(yellowLED,LOW);

digitalWrite(greenLED,LOW);

Serial.println("****NEWGAME****");

Serial.print("Startinggamein…");

//turnonredLED

digitalWrite(redLED,HIGH);

Serial.print("ready…");

delay(1000);

//turnoffredLED

digitalWrite(redLED,LOW);

//turnonyellowLED

digitalWrite(yellowLED,HIGH);

Serial.print("set…");

delay(1000);

//turnoffyellowLED

digitalWrite(yellowLED,LOW);

Serial.println("go!");

//turnongreenLED

digitalWrite(greenLED,HIGH);

//resetscore

currentScore=0;

}

ThestartGame()functionmakessurealltheLEDsareoffatthestartofthegameandthenturnsthemononebyone.Italsoprintscountdownmessages.Attheendofthefunctionthevariableholdingthecurrentscore,currentScore,isresetto0.

Insetup(),setthepinMode()toOUTPUTforeachoftheLEDsandcallthefunctionyoujustwrotesothatanewgamestartsautomaticallywhenyouturnontheArduinoUno.Thenewcodeyoushouldaddisinbold:voidsetup(){

//setuppinmodeforbutton

pinMode(buttonPin,INPUT_PULLUP);

//setuppinmodesforLEDs

pinMode(greenLED,OUTPUT);

pinMode(yellowLED,OUTPUT);

pinMode(redLED,OUTPUT);

//startserialcommunication

Serial.begin(9600);

//startcountdowntostart

startGame();

}

Uploadyoursketch,openSerialMonitorandtestthatitworks.YourLEDsshouldlightupintherightorderandcountdownmessagesshouldappearinSerialMonitor.

EndingtheGameToturnyourmarblemazeintoagame,youneedatimersotheplayercanscoreasmanypointsaspossiblewithinagiventime.

Tomakeatimerinyourcode,beginbyaddingthefollowingvariablestothetopofyoursketch.Youdon’tuseallofthemrightawaybuttheywillallbeusedinyourcompletedgame:intbuttonPin=7;

intmaximumTime=10000;

longgameStartTime;

booleanplayingGame=false;

ThefirstvariableyouuseisgameStartTime.Youmightnoticethatitisn’tanint—it’salong.YoufirstencounteredlonginAdventure6.Alongcanstoreabiggernumberthananint,whichwasneededforthecapacitivesensinglibrarythatyouusedtomakeyourcrystalball.HerethegameStartTimevariablestoresthetimecountedinthenumberofmillisecondssincetheArduinosketchbegan.Thatcouldbeaverybignumber,sothevariableshouldbealonginsteadofanint.

Inordertostorethetimethatagamestarts,youuseanewfunction:millis().Thisisabuilt-infunctionforArduinosoyoudon’tneedtoimportalibrarytouseit.Itreturnsthecurrentnumberofmillisecondsthathavepassedsincethesketchstarted.Youwanttosavethisnumbersothatyoucancheckandseehowmuchtimehasgonebysinceagamewasstarted.

AddthefollowinglineofcodetotheveryendofyourstartGame()function:gameStartTime=millis();

Inloop(),youthencheckandseeiftimehasrunout.ThevariablemaximumTimestoreshowlongagamecanrun.It’scurrentlysetto10,000milliseconds(10seconds),butyoucanmakethatshorterorlonger.

Addthefollowingifstatementtothetopofloop().Allthecodeyouhavewrittensofarinyourloopthatreadsinfromthepiezosandkeepstrackofthescoreshouldgoinsidetheifstatement.Thatway,newpointscanonlybescoredifthetimehasn’trunout:if((millis()-gameStartTime)<maximumTime){

//codeyouhavealreadywrittenthatkeepstrackofpointsbeing

scored

}

TheifstatementchecksthatthetimesincethegamewasstartedisstilllessthanmaximumTime.

ThevariableplayingGameisoneofthevariablesyoujustaddedtothetopofyoursketch.IthasaBooleandatatype.Thatmeansthevariablecanonlybeequaltotrueorfalse.Youareusingthevariableasaflag.Wheneveragameisbeingplayed,thevariableissettotrue,andwhenagameisn’tbeingplayedthevariableissettofalse.Youcanthenmakedecisionsincodebasedonwhetheragameisbeingplayed.

Aflagisavariableinaprogramthatkeepstrackofthestateofsomeotherpartofthecode.ItisusuallyaBoolean.

InstartGame(),addalineattheendofthefunctionthatsetstheflagplayingGametotrue:playingGame=true;

NowcreateanewfunctionattheendofyoursketchcalledendGame().Thisfunctioniscalledwhenthetimehasrunout.ItthensetstheplayingGameflagtofalse:voidendGame(){

Serial.println("GameOver!");

Serial.print("Score:");

Serial.println(currentScore);

//setflagthatnotcurrentlyplayingagame

playingGame=false;

}

Theifstatementchecksifagameiswithinthetimelimit.Ifthatisn’ttrue,youwantsomethingotherthanscoringpointstooccur.Ifthegameisbeingplayedandthetimehasrunout,youneedtoendthegame.Ifthetimehasrunoutandthegameisn’tbeingplayed,thenyouneedtodisplaywhetheranewhighscorewasachieved.Youcodethenewhighscorepartinthenextsection.Fornow,focusonendingthegame.

Inthecodethatrunsonlywhenthegameisn’tbeingplayedorthetimehasrunout,youuseanelsestatement.Anelsestatementcontainsthecodethatshouldberunonlywhentheconditionsintheifstatementarefalse.Itwon’trunthatcodeatanyothertime,andithastobepairedwithanif.

Insideyourloop,aftertheclosing}ofyourifstatement,addthefollowinglines:else{

//elseifplayingagamebuttimehasrunout

if(playingGame){

//endthegame

endGame();

}

}

Thecodeinintheelsestatementisrunonlyifthetimehasrunout.Theifstatementinsidetheelsestatementchecksifthegameflagisstillsettotrue.Ifitis,thenthegameisendedbycallingendGame.

UploadthesketchtoyourArduinoUnoandtestthatitworks.Itshoulddoeverythingthatithasbeendoingsofar—startingagameandkeepingtrackofthescore.NowitshouldalsoendthegameaftermaximumTime,whichissetto10seconds.

StartingaNewGameNowthatyourgameendsafteratimelimit,youneedawaytostartanewgametotryandbeatyourscore!Thenextstepistoaddabuttonthatstartsanewgame.Youalreadyhavethebuttoninthecircuitonyourbreadboard,soyouonlyneedtoaddthecode.

Insidetheelsestatementyoujustaddedintheprevioussection,addanotherelsestatementtotheifstatementthatischeckingwhethertheplayingGameflagistrue:else{

intbuttonValue=digitalRead(buttonPin);

if(buttonValue==0){

//buttonispressed,startnewgame

startGame();

}

}

NowiftheplayGameflagissettofalse,thebuttonischeckedtoseeifitisbeingpressed.Ifitis,thenanewgameisstartedbycallingthestartGame()function.

Theloop()nowhasthefollowingcode.UploadyoursketchtoyourArduinoUnoandtestthateverythingworks.AnewgameshouldstartwithitscountdownLEDswhenyoufirststarttheArduinoUno,anditshouldendafter10seconds.Ifyoupushthebutton,anewroundofthegamebegins:voidloop(){

//ifplayingagameandstillwithintime

if((millis()-gameStartTime)<maximumTime){

//readineachpointspin

inti;

for(i=0;i<numPointsPins;i++){

intcurrPinValue=analogRead(pointsPins[i]);

//ifabovethethreshold

if(currPinValue>piezoThreshold){

//addpoints

intnewPoints=(i+1)*10;

currentScore+=newPoints;

//printpointsandnewscore

Serial.print("Score!");

Serial.print(newPoints);

Serial.println("points");

Serial.print("Currentscore:");

Serial.print(currentScore);

Serial.println("points");

//pausesothatsamemarbledoesn’tscoretwice

delay(300);

}

}

}

else{

//elseifplayingagamebuttimehasrunout

if(playingGame){

//endthegame

endGame();

}

//elseifnotplayingagame

else{

//checkifbuttonhasbeenpressedtostartnewgame

intbuttonValue=digitalRead(buttonPin);

if(buttonValue==0){

//buttonispressed,startnewgame

startGame();

}

}

}

}

Bynowtheloop()isgettingalittlecomplicated!Figure9-9illustrateshowitallworks.Italsoshowswhatyouwillbeaddingnext—keepingtrackofthehighscore.

Figure9-9Howaloop()works

KeepingTrackoftheHighScoreAtthetopofyoursketch,addthreemorevariables:booleannewHighScore=false;

intcurrentScore;

inthighScore=0;

Youhaveaddedonemoreflag:newHighScore.Thisflagkeepstrackofwhetherthelastgameplayedresultedinanewhighscore.Ifitdid,thenthegreenLEDflasheswhenagameisn’tbeingplayed.Ifitdidn’t,thentheredLEDflashes.

InendGame(),addthefollowingcode.Itcomparesthelatestscorewiththesavedhighscore.Ifit’sanewhighscore,thentheflagissettotrue.Otherwiseitissettofalse:if(currentScore>highScore){

//ifanewhighscore

highScore=currentScore;

Serial.println("NewHighScore!");

newHighScore=true;

}

else{

//elsenewnohighscore

newHighScore=false;

}

NowyouneedtoaddthecodetomaketheLEDsflash.Inloop(),insidetheelsestatementwhereyoucheckthebutton,addthefollowingcode:if(newHighScore){

digitalWrite(greenLED,HIGH);

delay(200);

digitalWrite(greenLED,LOW);

delay(200);

}

//blinkredifflagisfalse

else{

digitalWrite(redLED,HIGH);

delay(200);

digitalWrite(redLED,LOW);

delay(200);

}

Uploadthesketchandcheckthatitworks.YoushouldbeabletostartagamewhentheArduinoUnoisturnedonorreset,thenwhenthegameendsthegreenLEDflashesifyougetanewhighscore.Ifyoudidn’tachieveanewhighscore,theredLEDflashesuntilyoustartanewgame.

Ifyouarehavingproblemsgettingyoursketchtocompilebecauseofatypo,trydownloadingthesketchfromthecompanionsite(www.wiley.com/go/adventuresinarduino).Readingthroughhowthecodeworksbeforetryingtotypeitallwillhelpyoubetterunderstandwhatisgoingon.

AddingSoundsYoualreadyhavewrittenthecodethatplayssoundswhenpointsarescoredinPartOneofthisadventure.Theonlythinglefttodoistoputitinitsownfunction.Thatmakesthecodeeasiertoreadandmakesiteasiertounderstandwhatisgoingon.

Cutthetwolinesofcodeinloop()thatplayasoundwhenapiezoistriggeredandputitinitsownfunctioncalledplayScoreMusicattheendofthesketch:voidplayScoreMusic(){

tone(speakerPin,659,300);

delay(300);

}

Nowyouneedtocallthefunctionyoujustwrote.Inloop(),callthefunctionrightafteryouhaveprintedthecurrentscore:playScoreMusic();

Therearejustthreemoretonesequencestocode.Thefirstisthemusicthatwillbeplayedwhenanewgamestarts.Attheendofthesketch,addanewfunctioncalledplayStartMusic()withthefollowinglinesofcode:voidplayStartMusic(){

tone(speakerPin,523,300);

delay(300);

tone(speakerPin,659,300);

delay(300);

tone(speakerPin,784,300);

delay(300);

tone(speakerPin,1047,500);

delay(600);

}

AttheendofstartGame,callthefunctionyoujustwrote:playStartMusic();

Oneoftwodifferenttonesequencesareplayedattheendofthegame.Whichoneisplayeddependsonwhetheranewhighscorewasjustachieved.Thesequencefornewhighscoresoundshappierthanthetonesplayedwhenyoudidn’tgetanewhighscore.

Attheendofyoursketch,addtheplayNewHighScoreMusic()andplaySadEndMusic()functions:voidplayNewHighScoreMusic(){

tone(speakerPin,880,300);

delay(200);

tone(speakerPin,440,500);

delay(200);

tone(speakerPin,880,300);

delay(200);

tone(speakerPin,440,500);

delay(200);

tone(speakerPin,880,300);

delay(200);

tone(speakerPin,440,500);

delay(200);

tone(speakerPin,880,300);

delay(500);

}

voidplaySadEndMusic(){

tone(speakerPin,698,300);

delay(300);

tone(speakerPin,622,300);

delay(300);

tone(speakerPin,587,300);

delay(300);

tone(speakerPin,523,500);

delay(600);

}

BothfunctionsarecalledwithintheendGamefunction.playNewHighScoreMusiciscalledinsidetheifstatementthatcheckswhetheranewhighscorewasachieved,andplaySadEndMusiciscalledinsidetheelse:if(currentScore>highScore){

//ifanewhighscore

highScore=currentScore;

Serial.println("NewHighScore!");

newHighScore=true;

//playnewhighscoremusic

playNewHighScoreMusic();

}

else{

//elsenonewhighscore

newHighScore=false;

//playendmusic

playSadEndMusic();

}

CHALLENGE

Trychangingthestartandendtone()sequencestocustomiseyourgame!

Andthat’sit!Younowhavethefullsketch.Thefullcodeisshownheresothatyoucancheckwhatyou’vewrittenagainstit.UploadthesketchtoyourArduinoUnoandtestitoutwithyourbreadboardcircuit.Afteryouarehappywithhowyourgameworks,youarereadytofinishbuildingyourmazegame!//variablesforpins

intpointsPins[]={

A0,A1,A2,A3,A4};

intbuttonPin=7;

intgreenLED=4;

intyellowLED=5;

intredLED=6;

intspeakerPin=9;

//numberofpiezosforpoints

intnumPointsPins=5;

//whenpointstriggered

intpiezoThreshold=800;

//gametimervariables

intmaximumTime=10000;

longgameStartTime;

booleanplayingGame=false;

//highscorevariables

booleannewHighScore=false;

intcurrentScore;

inthighScore=0;

//---setup---------------------------

//runsoncewhenboardfirstpowered

//orreset

voidsetup(){

//setuppinmodeforbutton

pinMode(buttonPin,INPUT_PULLUP);

//setuppinmodesforLEDs

pinMode(greenLED,OUTPUT);

pinMode(yellowLED,OUTPUT);

pinMode(redLED,OUTPUT);

//startserialcommunication

Serial.begin(9600);

//startcountdowntostart

startGame();

}

//---loop----------------------------

//runscontinuouslyaftersetup()

voidloop(){

//ifplayingagameandstillwithintime

if((millis()-gameStartTime)<maximumTime){

//readineachpointspin

inti;

for(i=0;i<numPointsPins;i++){

intcurrPinValue=analogRead(pointsPins[i]);

//ifabovethethreshold

if(currPinValue>piezoThreshold){

//addpoints

intnewPoints=(i+1)*10;

currentScore+=newPoints;

//printpointsandnewscore

Serial.print("Score!");

Serial.print(newPoints);

Serial.println("points");

Serial.print("Currentscore:");

Serial.print(currentScore);

Serial.println("points");

//playscoringmusic

playScoreMusic();

//pausesothatsamemarbledoesn’tscoretwice

delay(300);

}

}

}

else{

//elseifplayingagamebuttimehasrunout

if(playingGame){

//endthegame

endGame();

}

//elseifnotplayingagame

else{

//checkifbuttonhasbeenpressedtostartnewgame

intbuttonValue=digitalRead(buttonPin);

if(buttonValue==0){

//buttonispressed,startnewgame

startGame();

}

//blinkgreenifnewHighScoreflagistrue

if(newHighScore){

digitalWrite(greenLED,HIGH);

delay(200);

digitalWrite(greenLED,LOW);

delay(200);

}

//blinkredifflagisfalse

else{

digitalWrite(redLED,HIGH);

delay(200);

digitalWrite(redLED,LOW);

delay(200);

}

}

}

}

//---startGame---------------------------

//setsupvariablesforanewgameandstarts

//countdown

voidstartGame(){

//makesureallLEDsstartoff

digitalWrite(redLED,LOW);

digitalWrite(yellowLED,LOW);

digitalWrite(greenLED,LOW);

Serial.println("****NEWGAME****");

Serial.print("Startinggamein…");

//turnonredLED

digitalWrite(redLED,HIGH);

Serial.print("ready…");

delay(1000);

//turnoffredLED

digitalWrite(redLED,LOW);

//turnonyellowLED

digitalWrite(yellowLED,HIGH);

Serial.print("set…");

delay(1000);

//turnoffyellowLED

digitalWrite(yellowLED,LOW);

Serial.println("go!");

//turnongreenLED

digitalWrite(greenLED,HIGH);

//playstartmusic

playStartMusic();

//startgametimer

gameStartTime=millis();

//setflagthatcurrentlyplayingagame

playingGame=true;

//resetscore

currentScore=0;

}

//---endGame---------------------------

//setsupvariablesforanewgameandstarts

//countdown

voidendGame(){

Serial.println("GameOver!");

Serial.print("Score:");

Serial.println(currentScore);

//turnoffgreenLED

digitalWrite(greenLED,LOW);

//calculatehighscore

if(currentScore>highScore){

//ifanewhighscore

highScore=currentScore;

Serial.println("NewHighScore!");

newHighScore=true;

//playnewhighscoremusic

playNewHighScoreMusic();

}

else{

//elsenewnohighscore

newHighScore=false;

//playendmusic

playSadEndMusic();

}

Serial.print("HighScoreis:");

Serial.println(highScore);

Serial.println();

//setflagthatnotcurrentlyplayingagame

playingGame=false;

}

//---playStartMusic-----------------------

//playsstartingtonesequence

voidplayStartMusic(){

tone(speakerPin,523,300);

delay(300);

tone(speakerPin,659,300);

delay(300);

tone(speakerPin,784,300);

delay(300);

tone(speakerPin,1047,500);

delay(600);

}

//---playScoreMusic-----------------------

//playsscoringtone

voidplayScoreMusic(){

tone(speakerPin,659,300);

delay(300);

}

//---playSadEndMusic-----------------------

//playssadtonesequence

voidplaySadEndMusic(){

tone(speakerPin,698,300);

delay(300);

tone(speakerPin,622,300);

delay(300);

tone(speakerPin,587,300);

delay(300);

tone(speakerPin,523,500);

delay(600);

}

//---playNewHighScoreMusic-----------------------

//playshappynewhighscoretonesequence

voidplayNewHighScoreMusic(){

tone(speakerPin,880,300);

delay(200);

tone(speakerPin,440,500);

delay(200);

tone(speakerPin,880,300);

delay(200);

tone(speakerPin,440,500);

delay(200);

tone(speakerPin,880,300);

delay(200);

tone(speakerPin,440,500);

delay(200);

tone(speakerPin,880,300);

delay(500);

}

PartFour:BuildingtheMazeGameNowthatyouhaveyourcodeandcircuittestedandworking,it’stimetofinishbuildingyourmaze.Youaregoingtouseaboxwithnolid—sothreesidesandbottom,butnotop.Youwillbemakingapartialtopfortheboxthatcontainthemazeandholesforthemarbletodropthrough.Ifyouwanttocovertheboxwithpaintorpapertodecorateit,youmightfinditeasiertodobeforecuttingholesandassemblingtheelectronicsinsideit.

Youcanwatchavideoofhowtobuildyourmazegameonthecompanionsiteatwww.wiley.com/go/adventuresinarduino.

MakingtheMazeUsethefollowingstepstocreatethemaze:

1. Cutfourstripsofverythickpaperorcardthatarethelengthofyourmazeandapproximately3”(8cm)high.Foldoverabouthalfaninch(1cm)ofthecardsothatyoucangluethestripsofpapertotheinsideofthebox.Thesestripsstopthemarblefromrollingontoanotherpiezoandaccidentallytriggeringmorepointsafterithasdroppedfromthemaze.GluethestripsofpaperintoplaceasshowninFigure9-10.

2. Cutanotherpieceofcardboardabout2”(5cm)widerthanthebottomofyourboxwidthandabout2”(5cm)shorterthanthelengthofyourmaze.Youcanfoldtheextrainchoneachsideintoflapstohelpkeepthemazefirmlyinplaceinthebox.SeeFigure9-11asaguide.

3. Now’sthetimetofindthepieceofpaperonwhichyoucreatedyourdesignforthemazeearlierinthisadventure.Usingthisasyourguide,markthemazeandholelocationsonthepieceofcardboardthatyoujustcut.MarktheholesfortheLEDsandbutton.

4. Maketheholesinthecardboardforthemarble,LEDsandbutton,asshowninFigure9-12.

5. Create“walls”frompapertoformyourmaze.Cutstripsofpaperandfoldanedgetogluetothecardboardalongyourmazelines.

6. Usepaintormarkerstodecoratethecardboardinanywayyoulike—here’swhereyoucanletyourimaginationrunwild!Youprobablywanttoincludesomeindicationofthenumberofpointsthatcanbescoredateachhole.

Figure9-10Gluestripsofcardtoguidethemarbleafteritdropsthroughahole.

Figure9-11Lidofthemazegamefittedtobottom

Figure9-12Mazegamebeforeelectronics

AssemblingthePiezosYouarenowgoingtostartassemblingyourcircuit.Usethefollowingstepstoassemblethepiezos:

1. Markonyourboxwhereyourpiezos,LEDsandbuttonwillbelocated.2. Intheupper-rightcornerofyourbox,pokeaholethroughthecardboardsothatall

thewiresfrominsidetheboxcanpassthroughandeventuallyreachtheArduinoUnoontheoutsideofthebox.

3. CutwiresforeachofthepiezosthatreachfromtheredwireofeachpiezototheArduinoUno.Cutanothersetofwiresthatconnectalltheblackwiresfromthepiezostoeachother(seeFigure9-13).

4. Soldera1MΩresistorbetweentheredandblackwiresofthepiezos.Solderthewiresontotheresistoronthesamesideastheredwirefromthepiezos.Solderthewiresconnectingeachoftheblackwiresfromthepiezos.SeeFigure9-13forguidance.Labelthewiressoyouknowwhichwiregoestowhichpin.

Onlystartthesolderingstepswhenthereisanadultnearbytohelpyou.Solderingcanbedangerous,sobecareful!

5. InsertthesixwiressolderedtotheredwiresofthepiezosintotheirinputpinsontheArduinoUno.Insertthewiresolderedtothepiezos'blackwiresintoGND.Uploadthemazegamesketchandtestthatthepiezosallwork.Youshouldbeabletoscorepointswithfiveofthem,andthesixthshouldplaybackthesoundeffectsandmusic.

Figure9-13Wiringlayoutforpiezos

AssemblingtheLEDsandButtonWhenyou’resurethatanywetpaintorgluethatyouusedinyourdecorationshavedried,usethefollowingstepstoassembletheLEDsandbutton:

1. Solderacurrent-limitingresistorontoeachofthepositivelegsoftheLEDs.CutandsolderonwiresthatreachfromeachoftheresistorstotheArduinoUno.

2. CutandsoldertwowiresfromeachofthecontactsonthebuttonthatreachestotheArduinoUno.

3. PlacetheLEDsandbuttonintheirholesonthecardboardtoptothegame.SolderthenegativelegsoftheLEDsandonecontactofthebuttontogether.Figure9-14showswhatyoushouldhaveinfrontofyouonceyou’vefinishedsoldering.

Figure9-14SolderthenegativelegsoftheLEDsandonecontactofthebuttontogether.

CompletingtheFinishingTouchesYoujustneedafewfinishingtouchestocompletethisadventure!Usethefollowingstepstobringitalltogether:

1. Passtheallthewiresfromthepiezos,LEDsandpushbuttonthroughtheholeinbackofthebottombox.AttachtheArduinoUnototheoutsideoftheboxneartheholeforthewiresusingmaskingtape.

2. ConnectthewirestotheArduinoUnowiththesensorpiezosconnectingtoanaloginputs,andconnectthespeakerpiezo,buttonandLEDstodigitalpins.OnewireconnectingallthenegativewiresofthepiezosshouldconnecttooneGNDpin,andanotherwireconnectingthenegativelegsoftheLEDsandbuttonshouldconnecttoanotherGNDpin.

3. Testthatyourlights,buttonandpiezosareallactingasyouexpectbyplayingaroundofyournewgame.

Finished!Congratulationsoncompletingyourbigadventure!ThatwasalotofworkbutIhopeyoufounditrewarding.Youcannowrelaxbyplayingafewroundsofyournewmarblemazegame!

ArduinoCommandQuickReferenceTable

Command Description

booleanDatatypeforavariable.Canbeeithertrueorfalse.Seealsohttp://arduino.cc/en/Reference/BooleanVariables.

else Codethatisexecutedonlyiftheprecedingifstatementwasfalse.Seealsohttp://arduino.cc/en/Reference/Else.

millis()FunctionthatreturnshowlongtheArduinosketchhasbeenrunninginmilliseconds.Seealsohttp://arduino.cc/en/Reference/Millis.

FurtherAdventures:ContinuingYourAdventureswithArduinoTheArduinoisagreatwaytolearnaboutelectronicsandcodingbutofcoursethatisonlyhalfthefun.Asyou’veseen,projectsreallycomealivewhenyoustartembeddingyourArduinointophysicalobjects.Youhaveusedalotofdifferenthandtoolsandtechniques,butwhynotstartexploringdigitaltoolslikelasercuttersand3Dprinters?CheckoutMakeMagazine’ssite(http://makezine.com/3d-printing/)togetstarted.

Youcouldalsotaketheelectronicsandcodingskillsyou’velearnedwiththeArduinoandusethemwiththeRaspberryPi!CheckoutAdventuresinRaspberryPibyCarrieAnnePhilbin(Wiley,2014).

Mostimportantly,rememberthatyouarenowamemberofaworldwideArduinocommunity.YoucanalwaysfindmoreresourcesandtutorialsontheArduinowebsite(http://arduino.cc)alongwithaforumfullofnicepeoplereadytoansweryourquestions.

AchievementUnlocked:Arduinomastermind!

JUSTBECAUSEYOU’VEreachedtheendofyourArduinoadventureshere,itdoesn’tmeanyouradventuresarefinished!It’stimeforyoutoventureoutonyourown.Therearelotsofthingstoexploreandmanyresourcestohelpyouexplorethem.

MoreBoards,Shields,SensorsandActuatorsYouhavealreadylookedattwoArduinoboardsbesidestheArduinoUno:theLilypadandLeonardo.Arduinoscomemanyshapesandsizes,soifyouhaveaprojectinmind,explorewhatmightbebestforit.Doesitneedtobesmall?TheSparkfunArduinoProMini(www.sparkfun.com/products/11113)orArduinoMicro(http://arduino.cc/en/Main/ArduinoBoardMicro)mightbeperfect.Doyouwanttoaddlotsoftouchsensorsandplayaudiofiles?TheBareConductiveTouchBoard(www.bareconductive.com/shop/touch-board/)doesthatallonasingleboard!

ShieldsAshieldisasolderedcircuitthatfitsperfectlyontopofyourArduinoUnoboard.ItcanholdsomecomplicatedcircuitrylikeanArduinoEthernetShield(http://arduino.cc/en/Main/ArduinoEthernetShield)thatletsyouconnectyourArduinototheInternetwithanEthernetcable.Thereareshieldsthataddtouchscreens,MP3players,motorcontrolandmuchmore.Visityourfavouritestore—whetherinpersonoronline—andseewhat’savailable.

SensorsandActuatorsTherearealsomanymoresensorsavailablethanyou’veusedfortheadventuresinthisbook.Justaboutanythingyoucansense,youcangetyourArduinotosenseaswell.Wanttodetectthebarometricpressure?TrytheBMP180(www.adafruit.com/products/1603).Howaboutsound?TryanelectretmicrophonefromSparkFun(https://www.sparkfun.com/products/9964).

Thesamegoesforactuators.Therearemanytypesofmotorandspeakerand,ofcourse,thereisahugeselectionofLEDsandscreens.TheAdafruitNeoPixelisagreatRGBLEDthatyoucancontrolwithanArduino(www.adafruit.com/category/168).

Ofcourse,analternativetobuyingmoresensorsistomakeyourown!Kobakant’sHowtoGetWhatYouWant(http://kobakant.at/DIY)isacollectionofguidesanddocumentationonDIYsensors,oftenusingmaterialslikeconductivethreadandfabric.

OntheWebThewebisfullofprojectsandresources.Onlyafewofthemostpopularonesarelistedhere,sosearcharoundformore!

TheArduinoSiteThefirststopforanyaspiringArduinoengineeristheArduinowebsite(http://arduino.cc).YouwillfindeverythingyouneedtoknowabouteveryofficialArduinoboardthatismade—andtherearealotofthem.It’salsothehomeoftheArduinoplayground(http://playground.arduino.cc)whereArduinouserscanuploadtheirownprojectsandtutorials.

Ifyouhaveanyquestionsorproblemstryingtobringaprojecttolife,youcanaskaquestionontheArduinoForum(http://forum.arduino.cc).Therearealwaysfriendlyfolkwillingtohelp,butit’sgoodtodoacoupleofthingsbeforeaskingaquestion.First,makesureit’snotaquestionthathasalreadybeenasked.Searcharoundtheforums—maybesomeoneelsehasalreadyprovidedalltheinformationyouneed.Second,giveasmanydetailsasyoucan.Describewhatyouhavetriedtodo,whatyouwanttohappenandexactlywhatisactuallyhappening.Thismakesitmucheasierforotherstohelpyouandmorelikelythattheywillreply.

ManufacturersOtherthantheArduinowebsite,thebestresourcesaretwocompaniesthatbuildtheirownsensors,actuatorsandkitsfortheArduino:SparkFunandAdafruit.Bothhaveexcellentsitesfulloftutorialsandguides.Adafruitisathttps://learn.adafruit.comandSparkFunisathttps://learn.sparkfun.com.

BlogsIfyouareinneedofsomeinspirationforyournextproject,tryoutAdafruit’sblog(http://adafruit.com/blog),MakeMagazine(http://makezine.com)orHackaday(http://hackaday.com).Therearelotsofspecialistblogsaswell.Forexample,ifyouareintowearabletechnology,keepyoureyeonFashioningTechnology(http://fashioningtech.com).WanttotakeyourArduinototheskies?DIYDrones(http://diydrones.com/)canhelpyouwiththat.

VideosSometimesnothingbeatsseeingavideodemonstrationofanewskill.YouTubechannelsareagreatwaytolearnaboutanewsensororhowtomakeanewproject.Youwon’tbesurprisedtolearnthatbothAdafruit(https://www.youtube.com/user/adafruit)andSparkFun(https://www.youtube.com/user/sparkfun)haveYouTubechannelsoverflowingwithinformation.MakeMagazinehasoneaswell(https://www.youtube.com/user/makemagazine).

Foranexcellentseriesofelectronicsvideos,searchYouTubefor“Collin’sLab”.CollinCunninghamteachesbasicelectronicsinawaythat’seasytofollow.SomeofthevideosaremadewithMakeMagazineandothersarefromAdafruit,sojustsearchfor“Collin’sLab”.

MassimoBanzi,oneofthefoundersofArduino,madeaseriesofvideosthataccompaniestheofficialArduinoStarterKit.Thevideoshaveaprojectbook,butyoucanonlygetitbybuyingthekit.Thefirstvideoisathttps://www.youtube.com/watch?v=2X8d_r0p92U.

BooksPhysicalbooksaregreattohaveonhandforreference.Therearealotofthemoutthereandmorearebeingwrittenaboutthelatesttechnologyallthetime,buthereareafewtogetyoustarted.

GettingStartedwithArduinoandGeneralProjectsTherearefarmoreprojectsyoucanmakewithanArduinothanyouhavemadewiththisbook.Gooutandmakeevenmoreprojects!Buildmorethings!

GettingStartedwithArduinobyMassimoBanzi(MakerMedia,Inc.,2011)ArduinoForDummiesbyJohnNussey(Wiley,2013)ArduinoProjectsForDummiesbyBrockCraft(Wiley,2013)ExploringArduino:ToolsandTechniquesforEngineeringWizardrybyJeremyBlum(Wiley,2013)

GeneralElectronicsElectricalcircuitsincludemuchmorethanjustArduinos.Ifyouwouldliketostartmakingreallyadvancedprojects,it’sagoodideatolearnmoreaboutcircuits.Thesebookscangetyougoing:

Make:ElectronicsbyCharlesPlatt(Make,2009)PracticalElectronicsforInventorsbyPaulScherzandSimonMonk(TabBooks,2013)

SoftCircuitsandWearablesElectronicsandcraftingtechniqueslikesewingactuallygotogetherreallywell.Ifyou’reinterestedinexploringthisperfectmatch,herearesomegreatbookstogetyoustarted:

FashioningTechnologybySyuziPakhchyan(MakerMedia,Inc.,2008)SwitchCraft:Battery-PoweredCraftstoMakeandSewbyAlisonLewisandFang-YuLin(PotterCraft,2008)SewElectricbyLeahBuechley,KanjunQi,andSonjadeBoer(HLTPress,2013)Make:WearableElectronicsbyKateHartman(MakerMedia,Inc.,2014)

OtherSpecialisedTopicsOfcourse,therearesomanymorethingsthatArduinoscando.HowaboutinvestigatingArduinorobotsorArduinosthatcantalktotheInternet?

MakingThingsMove:DIYMechanismsforInventors,Hobbyists,andArtistsbyDustynRoberts(McGraw-Hill,2011)MakingThingsTalk:UsingSensors,Networks,andArduinotoSee,Hear,andFeelYourWorldbyTomIgoe(MakerMedia,Inc.,2011)

NAVIGATINGYOURWAYthroughtheworldoftoolsandelectricalcomponentscanbedifficult,butluckilythegrowthofdo-it-yourselfelectronicsandcodingprojectshasmadeiteasierthaneverbeforetofindwhatyouneedforyourArduinoproject.

StarterKitsAreallyeasywaytogetgoingwiththeadventuresinthisbookistobuyastarterkit.AstarterkitwillincludeanArduinoUnoandalmostallthecomponentsyouneedlikeLEDs,resistorsandaservo.YoucancomparethelistofcomponentsyouneedintheIntroductionwithwhatisavailableinastarterkitandthenbuywhateverisn’tincluded.YouwillstillneedtobuyanArduinoLeonardoandLilypadArduinoUSBseparatelytocompleteAdventures7and8

Almostallthestoreslistedinthisappendixselltheirownstarterkits,sotherearelotsofoptions.TheArduinocompanymakesitsownstarterkitthatcomeswithawholebookofprojects.YoucanbuyitfromaresellerordirectlyfromtheArduinoshoponline(http://store.arduino.cc/product/K000007).

Brick-and-MortarStoresAbrick-and-mortarstoresimplymeansashop!Beingabletowalkintoastoretofindthecomponentsyouneedhassomebenefits.Forexample,whenworkingwithphysicalcomponents,it’salwaysusefultobeabletopickthemupandseethemforyourself.Youcanalsoaskquestionsfromthehelpfulstaffinthestore.Plus,youdon’thavetowaitforyourpackagetobedelivered;youcangohomeandgetmakingrightaway!

IntheUKMaplin(www.maplin.co.uk)sellsallsortsofthingsandhasawiderangeofstock;youcannowbuyArduinosthere,alongwithelectricalcomponents.MostofthesmallercomponentslikeresistorsandLEDsarekeptbehindthecounter,soyoucanlookuptheproductcodeinacatalogueorin-storecomputerandamemberofstaffwillgetitforyou.Theyalsostockusefultoolslikesolderingirons.

IntheUSRadioShack(www.radioshack.com)hadlongbeentheplaceforhobbyistelectronics.Thechainfiledforbankruptcyin2015,leavingthoseintheUnitedStateswithoutaphysicalstoretovisit.Thereisn’tyetachainaslargeasRadioShacktotakeitsplace,butspaceslikeTechShop(http://techshop.ws/)arebecomingmorewidespreadandcontainshopssellingelectronics.

OnlineStoresTherearebroadlytwodifferentkindsofonlinestoreforelectricalcomponents:friendlyhobbyistorspecialistsites;andvastcataloguesites.Ifyouarejuststartingout,it’sbettertostickwithafriendlysitethatdoesn’tstocksomanydifferentoptionsbutdoesstockwhatyouwillmostlikelyneed.

Thebiggersiteshavethousands,ifnotmillions,ofcomponentssocanbedifficulttonavigateifyoudon’tknowexactlywhatyouarelookingfor.However,theytendtobecheaperthanotheronlinestoresandalsostocklesspopularitemsthatarehardertofind.

OnlineStoresShippingfromtheEUAdafruitandSparkfunarethebestsitesforreference,butyoumightnotwanttodealwithinternationalshippingifyoudon’tliveinNorthAmerica.LuckilytherearealargenumberofEUdistributorsthatimportAdafruitandSparkfunproducts.Thatmeansyoucangetmakingfaster!Trysomeofthesesitestoseeiftheyhavewhatyouneed:

ArduinoStore:http://store.arduino.ccCoolComponents:www.coolcomponents.co.ukMaplin:www.maplin.co.ukOomlout:http://oomlout.comPimoroni:http://shop.pimoroni.comProto-Pic:http://proto-pic.co.ukRobotShop:www.robotshop.com/eu/enSKPang:http://skpang.co.uk

SomebigcataloguesitesthatservetheEUincludethefollowing:

Digi-Key:www.digikey.co.ukFarnell:www.farnell.comMouser:http://uk.mouser.comRapid:www.rapidonline.comRSComponents:www.rs-components.com/index.html

OnlineStoresShippingfromtheUSorCanadaThetwomaker-focusedsitesthatallothermakercompaniesaspiretobeareAdafruit(www.adafruit.com)andSparkfun(https://www.sparkfun.com).Bothhaveexcellentguidesandtutorialsforhowtouseeverythingtheysell.Alotoftheirstockoverlaps,buteachcompanyalsomakestheirownproducts.Thesesitesshouldalwaysbeyourfirststoponline.TheyarebothlocatedintheUS,soreadontothenextsectionifyouarenotinNorthAmericaanddon’twanttowait(orpay)foryourordertoarrivefromfaraway.

YoucanalsocheckouttheseothersmalleronlinesitesthatarealsointheUS:

MakerShed:www.makershed.comRobotShop:www.robotshop.comSpinkenzieLabs:www.spikenzielabs.com

IfyouwanttotryoneofthelargecataloguesitesbasedintheUS,checkoutsomeofthese:

AlliedElectronics:http://ex-en.alliedelec.comDigi-Key:www.digikey.comJameco:www.jameco.comMouser:www.mouser.comNewark:www.newark.com

actuatorAdevicethattranslatesanelectricalsignalintoareal-worldactionsuchaslight,soundormovement.Examplesincludemotors,lightsandspeakers.

alligatorclipsWireswithspring-loadedclipsthatresemblethejawsofanalligator.Theyareusefulforprototypingsoftcircuitsorconnectingcomponentsthatdon’tusejumperwires.

analogueAsignalthatvariesbetweenLOWandHIGH,asopposedtoadigitalsignal.OntheArduinoUno,ananaloguesignalcanbemeasuredasanumberbetween0forgroundand1023for5V.Ananaloguesignalcanbeoutputasavaluebetween0for0Vand255for5V.

anodeThepositivelegofadirectionalcomponent,suchasthelonglegofanLED.

argumentApieceofinformationgiventoafunction,whichthefunctionthenusestoperformitstask.Theargumentgoesinsidethebracketsthatfollowthefunctionname.Forexample,thefunctiondelay(1000)hastheargument1000,whichisthenumberofmillisecondsyouwanttheArduinotowaitbeforeexecutingthenextline.

arrayAlistofthesametypeofthingincode.Forexample,anarraycanholdalistofints.

binaryAnumberthatusesonlythedigits0and1,asopposedtodecimal,whichusesthedigits0to9.Binaryisalsoknownasbase-2.Decimalisreferredtoasbase-10.

breadboard

Areusabledevicethatallowsyoutocreatecircuitswithoutneedingtosolderallthecomponents.Breadboardshaveanumberofholesintowhichyoupushwiresandcomponentstocreatecircuits.

capacitanceTheabilitytostoreanelectricalcharge.Electricalcomponentsbuiltespeciallytoholdachargearecalledcapacitors,butotherobjects—evenpeople—alsohavecapacitance.

cathodeThenegativelegofadirectionalcomponent,suchastheshortlegofanLED.

commentsNoteswithinyourcodethatexplainwhatalineorsectionofcodeisintendedtodo.Eachcommentlinebeginswith//or,ifyouwanttowriteacommentthatspansmultiplelines,itisplacedbetween/*and*/.Thesespecialcharacterstellthecomputerrunningtheprogramtoignorethatlineorlines.

compilingTheprocessoftakingcodewrittenbyahumanandturningitintoinstructionsthatcanbeunderstoodbyamachine.

currentTherateatwhichelectricalenergyflowspastapointinacircuit.Itistheelectricalequivalentoftheflowrateofwaterinpipes.Currentismeasuredinamperes(A).Smallercurrentsaremeasuredinmilliamperes(mA).

debuggingTheprocessoflocatingthecauseofanyerrorsinyourcomputerprogramcodeandfixingthem.

declaringWhereanewvariableiscreatedbygivingitanameandadatatypesuchasint.Thevariabledoesnotholdavalueuntilitisgivenitsfirstvalue.

digitalAsignalthatisonlyeitheronoroff,orHIGHorLOW.OntheArduinoUno,aHIGHsignalis5VandaLOWsignalisground.

directcurrent(DC)ThetypeofelectricityusedinArduinocircuits.It’sthesamekindthatis

generatedbyabatteryandistheoppositeofalternatingcurrent(AC),whichiswhatcomesoutofmainsplugsinthewall.

driverApieceofsoftwarethatletsyourcomputercommunicatewithanexternaldevice,suchasaprinterorakeyboard.

dualin-linepackage(DIPorDIL)OnepossibleshapeofanICchip.Ithastworowsoflegsthatcanfitintoabreadboard.

dutycycleTheratiooftimeasignalisHIGHversusLOWinagivencycle.InPWM,thehigherthedutycycle,thehighertheoutputvoltage.

floatAdatatypefornumbersthataren’twholenumbers,butincludeadecimalplacesuchas1.3or–54.089.

floatinginputApinthatisnotconnectedtoanything.Thepinreadsinrandomvaluesifitisnotconnectedtoavoltagesourcesuchasground,5Vorasensor.

forloopAprogrammingdevicethatrepeatsablockofcodeforapredeterminednumberoftimes.

functionAsetoflinesofcodethathaveaname.Afunctioncanbeusedoverandoveragain.Itmaytakesomeinformationasaninputandoutputmoreinformationwhenitisfinished,butnotallfunctionsneedtodothat.

instantiationGivingavariableavalueforthefirsttime.Instantiationcanhappenatthesametimeyoudeclarethevariableoryoucandoitlater,butthedeclarationalwaysneedstocomefirst.

integratedcircuit(IC)Circuitscontainedwithinasinglechip.Thesamecircuitcanbeputintodifferentshapedchips,calledpackages.Whenworkingwithabreadboard,youneedwhatisknownaDIPorDILpackage.That’stheshapethathaslegsthatfitintoabreadboard.

integrateddevelopmentenvironment(IDE)Asoftwareapplicationthatisusedtowritecomputercodeinaparticular

language;it’salsoreferredtoasaprogrammingenvironment.Theapplicationcancreateandeditcode,aswellasrun(orexecute)thecode.ManyIDEsalsoprovidefeaturestohelpprogrammersdebugtheirprograms—inotherwords,checktheirprogramsforerrors.

light-emittingdiode(LED)Anelectricalcomponentthatlightsupwhenelectricalcurrentflowsthroughit.Adiodeonlyletselectricityflowinonedirection,soanLEDlightsuponlywhenthelonglegisconnectedtothepositivesideofapowersourceandtheshortlegisconnectedtothenegativeside.Ifthelegsareswitched,theLEDwon’tlightup.

libraryAcollectionofreusablefunctionsincodethatcanbeimportedandusedinmultiplesketches.

light-dependentresistorAresistorthatchangesitsresistanceaccordingtohowmuchlightitisexposedto.Itisalsosometimescalledaphotoresistor.

longAdatatypethatcanholdwholeintegernumbersfrom–2,147,483,648to2,147,483,647.

newlinecharacterAcharacterthatrepresentswhathappenswhenyoupresstheEnterorReturnkeyonyourkeyboard.

Ohm’sLawThemathematicalrelationshipbetweenvoltage,currentandresistance.Voltageequalscurrentmultipliedbytheresistance—or,putanotherway,V=IR.

panelmountpushbuttonApushbuttonthatisdesignedtobemountedinsideacase.Itcomeswithanutandwashertosecureittoapanel.

piezoAcrystalthatexpandsandshrinkswhenelectricityisrunthroughit.Italsogenerateselectricitywhenitissqueezedorbent.

potentiometerAtypeofresistorwithanadjustableknobtovarytheresistanceofcurrent.

pull-upresistor

Aresistorthatisconnectedtothehighvoltageinacircuit,whichsetsthedefaultstateofthepinonthatcircuittoHIGH.Theresistorisusually10kΩ.

pulsewidthmodulation(PWM)HowtheArduinoboardgeneratesanoutputsignalbetween0Vand5V.ThesignalswitchesquicklybetweenLOWandHIGHandtheresultingoutputvoltageisbetweenthetwovoltages.

red-green-bluelight-emittingdiode(RGBLED)AsingleLEDwithfourlegsthatcontainsthreelights:onered,onegreenandoneblue.Thethreelightsshareeitheracommonanodeoracommoncathode.

resistorAnelectricalcomponentthatresistscurrentinacircuit.Forexample,LEDscanbedamagedbytoomuchcurrent,butifyouaddaresistorwiththecorrectvaluetotheLEDcircuittolimittheamountofcurrent,theLEDisprotected.ResistanceismeasuredinohmsorΩ.Youneedtopickaresistorwiththecorrectvaluetolimitthecurrentthroughacircuit;thevalueofaresistorisshownbycolouredbandsthatarereadfromlefttoright.

sensorAdevicethatdetectssomethingintherealworldsuchaslight,soundormovementandtranslatesitintoanelectricalsignal.Examplesincludepotentiometersandlight-dependentresistors.

serialcommunicationAwaythattwodevices,suchasacomputerandanArduinoboard,cansendandreceivedatatoeachother.Onepieceofdataissentatatime.

servoAmotorthatcanbecontrolledtorotatetoaspecificposition.Itusuallycan’trotatemorethan180degrees.

shiftregisterAdevicethatcancontrolmultipleoutputswithrelativelyfewinputs.ItiscommonlyusedtocontrolalargenumberofLEDs.

sketchesArduinoprograms.Thenamecomesfromthequickdrawingsartistsmake.

softcircuit:Circuitbuiltwithflexiblematerialssuchasconductivethreadandfabric.Softcircuitsareoftenusedinprojectsthataregoingtobeworn.

surface-mountdevice(SMD)OnepossibleshapeofanICchiporothercomponentsuchasaresistor.Itismadeforsolderingontoaflatsurfacewithoutanylegsbeinginsertedintoholesonacircuitboard.

switchAcomponentthateitherdisruptsorredirectstheflowofcurrentinacircuit.

tactilepushbuttonAtypeofswitch.Apush-to-breakpushbuttoninterruptstheflowofcurrentinacircuitwhenitispressed.Apush-to-makepushbuttondoestheoppositeandinterruptscurrentonlywhenitisnotpressed.

two-dimensionalarrayDatastoredinrowsandcolumns,likeinaspreadsheet.

variableAcodeconstructthatholdsavaluethatcanbechanged.Forexample,thevariablegreenLEDstoresthenumber5.

voltageThedifferenceinelectricalenergybetweentwopointsinacircuit.Itistheelectricalequivalentofwaterpressureinpipes,anditisthispressurethatcausesacurrenttoflowthroughacircuit.Voltageismeasuredinvolts(V).

voltagedividerAcircuitthatoutputsafractionoftheinputvoltage.Itisausefulcircuitfortranslatingachangeinresistanceintoachangeinvoltage.

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