Embedded System Project (521423S)

Juha RöningAntti Tikanmäki

Anssi Kemppainen

About the course

• The goal of this course is to help students understand the world of embedded computer systems by developing an embedded system.

• Usually participants are information and electrical engineering students who are specialized in software and system design.

• The Embedded System Project is related to but independent of Embedded Software Project (Sulautettujen ohjelmistojen projekti, 521275A) that concentrates on software-hardware interface.

• A project like assignment that requires approximately 120-160 hours from a team of three students.

• This course is structured as a guided walk through the hardware design process.

– Consists of the beginning lecture and five meetings with the assistant

– Each meeting is after one design phase. The previously done work is checkedand the next phase explained in each meeting.

About the course

In this course students:

• Go through complete design and implementation process of a device

• Do formal requirement specification and technical specification

• Select and order suitable components for the device

• Create schematics, layout and manufacturing files for PCB

• Populate PCB and test the board

• Design and implement software for the device

• Do formal testing to verify that the device fill the requirements

• Write documentation (during whole process)

Project phases

Design phases

In practice:

1. Requirement specification, Technical

specification, test plan, Schedule

2. Schematics, component ordering

3. Layout and manufacturing files, PCB

ordering

4. Populating the board and electrical

testing

5. Programming software and testing

6. Final demonstration and Final report

System requirements

Sketch of software

Sketch of hardware

Evaluation and simulation against requirements

Detailed HW-design

Test design

PWB and assembly

Software

HW-tests Simulator tests

Integration

operation procedures

modes, functions, algorithms, control

testability considerations

embedded software design

EEPROM programming

power consumption, environment etc.

partitioning, basic solutions

schematics and layout

printed wiring board manufacturing

continuity and HW functionality

Phase 1: Planning

Requirement specification

• List of features

– Figure out what is the purpose and required functions of your device

• Numerical requirement (like storage, power, time of operation)

– For example: logging 10 hours of motor temperatures from 4 places twice in a

second to SD card

-> You will find requirements for memory, storage, power usage, calculation

speed, size of device,…

– You need to have numerical requirements when selecting for example

temperature sensor from 1365 options available in digikey

• Use numbering and hierarchy:

– Req_1: User interface,

– Req_1.1: operating buttons, …

– Req_2: Measuring temperature

Phase 1: Planning

Technical specification

• Study AVR application notes and component datasheets

• Technical solution for ReqSpec

• Component comparison and choices

• Select Microcontroller that contains suitable features (like I2C,SPI,…)

– In this course, prefer 8bit AVR MCUs

• Calculations of values

• Define size of passive components

• Try to have only one voltage, like 5V or 3.3V if possible.

• Read through datasheets of selected components, especially for controller!

– Try to use build in functionalities, like uart,spi, i2c, adc, …

• Select components that are available in stock and reasonable price

• Software specification

Phase 1: Planning

Test plan

– How to verify that each requirement is filled

• Calibration? Reference measurement?

• Example: temperature measurement with reference device

– How to test that technical solutions works as expected

– If minimum and maximum requirement exist, how to measure in these conditions

– Use same reference numbering as in previous documents

Schedule

– Reserve weekly hours that you are able/will spend on this project

– Deadlines for each phase to complete project in time

• Define what needs to be done before DL

– Continuously update LOG of used hours to learn how much time each job is

taking in practice in design process

– Keep your time schedule

• If schedule is missed, do rescheduling

– Report progress in week-reports

Phase 2: Schematics, component ordering

Information sources:

• The datasheets of components

• Study Atmel Application notes

• "typical application“ from datasheets

Practical schema design issues:

• Know what is a pullup or pulldown resistor

• Use filtering capacitors

• How to regulate operating voltage

• Don’t forget testing points (HW)

• Never connect any output directly to the ground or power supply

Some tips:

• Use comments on schema to clarify solutions

• When technical specification is complete, group is allowed to order components

• Use component order list provided in course web page

Tools:

• Kicad http://www.kicad-pcb.org/

Phase 3: Layout and manufacturing files, PCB

ordering

Layout:

• Aim for short tracks to avoid inductance disturbances

• You can use SMD components

• Route your board with such a principle that you use top layer for vertical tracks and

bottom layer for horizontal tracks. Or vice versa.

• Clear routes help on debugging

• Place the filter capacitors of IC components as close as possible to the IC:s Vcc and

Gnd pins.

• Choose the track width according the average current that goes through it.

• Remember test pins

• Connect the extra copper of your board to ground

Phase 3: Layout and manufacturing files, PCB

ordering

Manufacturing files:

• After drawing a layout, print it as a 1:1 size print and try if the components fits

• Run Design Rule Check (DRC) against given parameters

• Check Gerber files with Kicad’s Gerber view program

PCB ordering (when permission given by Assistant):

• Manufacturing at our own workshop

• Manufacturing in FABLAB CNC

• If you want to have your own boards: Order from China for example from:

http://imall.iteadstudio.com/open-pcb/pcb-prototyping.html

10 pieces 50x50mm at 9.90 $

Phase 4: Populating the board and electrical

testing

• Hand operated SMD pick and place manipulator for populating the board in FABLAB

• For physical measurement of electrical features

– Oscilloscopes

– Multimeters

• Measure all soldering for short circuits before connecting the power

• For powering up the device

– DC power sources

– Batteries

• Testing

– Work systematically

– Use scope to test availability of signals

– To test some of the functionalities, you need software routines

Phase 5: Software

Software design:

• Develop the software parallel to hardware, especially separate testing routines for

verifying that hardware is working correctly

• You may use C or C++, if very time critical is involved, use assembly

• You may use open source libraries / functions to get devices working

• Design SW timing, like how many times in second something is done

Coding:

• Split software to modules. For example SPI.c, I2C.c, X_sensor.c

• Main.c should contain only high level function calls and main loop

• Design use of interrupts and polling

• Don’t write too long functions

• Study what is meaning of const, struct, volatile, pointers and how to use eeprom

• Study how globals works in practice

• Decide variable types (unsinged or signed? 8,16 or 32 bits? Floats?)

• Use struct pointers in function calls instead of many parameters

• You can measure your software timing in practice by using extra mcu pins and scope

Tools: Software development and debugging

environmentFor software developing and debugging• Windows: with Atmel-Studio IDE and WinAVR compiler (avr-gcc)• Linux: Atmel AVR toolchain

• AVR JTAG ICE Emulator

• The self-made PCB contains an MCU with a JTAG interface for connecting to AVR JTAG ICE. The MCU contains an on-chip debug block, which is used for debugging. ICE connects to this block via JTAG interface.

• The software is uploaded to the Flash memory of an MCU with AVR JTAG ICE and ran normally.

• The on-chip debug block allows debugging the software similarly to PC: stepping the code, reading variable values, break points, etc. Additionally, all the registers of the MCU are available for modifying.

• When software works properly with AVR JTAG ICE, power off the device, disconnect AVR JTAG connector and you are ready to run the device independently. No further software uploads are necessary because the software is always ran in MCU.

PCB

MCU

Flash

memory

O

C

D

Core

Other

blocks

JTAG-

conne

ctor

AVR

JTAG

ICE

PC

- AVR-

Studio

IDE

- WinAVR

compiler

USB

emulator cable

Course procedure

Course procedure

• Send e-mail to assistant (antti.tikanmaki@ee.oulu.fi) containing who areyour group members. Your assistant (Antti or Anssi) will reply to you givingyou a group number

• Name all your documents and e-mail messages with your group number

– Group1_technical_specification.pdf, etc.

• First face-to-face meeting should be in 2-3 weeks after the start. Otherwisemany students are tempted to delay their full commitment, resulting in largedelays in completion.

Each group needs to send short weekly report using email containing

progress and next things to do to prove that work is progressing as scheduled

Course procedure

• The assistant will have at least 5 scheduled 15-30 minute meetings with each group.

• Send documents to be reviewed one day before the meeting

• During the meetings the teams will describe their solutions, ideas and encounteredproblems, helping the assistant to correct serious design flaws at an early stage.

• The meetings also encourage to the planned use of time, instead of painful around-the-clock marathons as the deadline approaches.

• The contents of the meetings is as follows:

1. Inspection of requirement and implementation specification, and timetable.Advice on schematics and component list for students.

2. Inspection of the schematics, component order list and inspection of refinedspecifications. Advice on layout for students.

3. Inspection of layout printed in 1:1 scale. Footprint check and permission formanufacturing the PCB.

4. Inspection of an assembled board. Advice on the emulator and AtmelStudio usefor students.

5. Demonstration of working board. Documentation and board left for grading.

Deliverables

1. Specification document containing– Requirement specification

– Implementation specification

– Test plan

2. Project plan

– Schedule– log of work process

3. Schematic and layout of the PCB

4. Software

5. A prototype of the device and demonstration

6. Final report containing– Device description

– User manual

– Test report

– Overall description of the implementation and future development

At the end, send all documents as zip file for complete review and grading

Grading

Grading is based on

• Documentation (on each Phase)

• Board design

– How well the given design guidelines are used

• The sanity of the design (schematics check: pullups, filtering, hazardous connections)

• Some jump wires will not affect to the grading. The students must be able to

experiment.

• The number of created board versions will not be considered, since it

consumes so radically time to make another iteration of a board.

• Inspection against requirements

– Check each requirement

– Assessment of the stability of the system

• Keeping of the schedule

Deadlines

31.1. Phase 1 completed – all plans ready

15.3. Phase 2 completed – schematics and component orders

30.3. Phase 3 completed – Layout ready, manufacturing ordered

30.4. Phase 4 completed – PCB manufactured, populated and tested with basic software

30.5. Phase 5 completed – All functionalities operating, Documentation ready

Lectures

3 times to give practical tips for each project phase:

16.01. ma 14.15-16.00 Specifications, TS128

23.01. ma 14.15-16.00 Schematics, layout, TS128

30.01. ma 14.15-16.00 Software and testing, TS128

06.02. ma 14.15-16.00 Software and testing, TS128

Each lecture contains 10-15 minutes briefing lecture, and after that free discussion

related to own projects

Topics

About the topic

The basic requirements:

• meant for people that are new to the embedded systems.

• contains only familiar technologies and the teachers are familiar with the topic,enabling more efficient tutoring

• some suitable components for the assignment have been pre-examined, letting thestudents to avoid the full exposure to “navigation” problems, such as selecting,finding, and ordering components

Other features:

• The teams are free to create additional features to their system if they will.

• These additional features affect positively (to a certain extend) to the grading of the

team

Own topics:

• meant for students with some experience in embedded systems

• Students suggest a subject, assistants help refine it, and professor accepts it.

• If you want the PCB after the course ends, you must buy the main components.

Addition to basic topic, some special research related topics may be available on

course web page within few weeks after course start day

Aihe 1: Langaton kiihtyvyys/kallistusanturi

• Ominaisuudet:

– 9Dof IMU-sensori

• LSM9DS1 breakout board: https://www.sparkfun.com/products/13284

• MPU-9250 breakout board: https://www.sparkfun.com/products/13762

– akku ja latauspiiri

– radio: joko BTLE-, WLAN- tai UWB-radio

– käyttöliittymän napit ja ledit / näyttö / visualisointi

• Sovellusvaihtoehdot johon opiskelijat toteuttavat:

– Aktiivisuusranneke

– asentotiedon mittaus (kiinnitetään esim. kameraan)

– ihmisen pään asennon mittaus (kiinnitetään päähän)

– Urheilusovellus, esim. mailan asento

Aihe 1: Langaton kiihtyvyys/kallistusanturi

• Lisäoptiona voi toteutatta jonkin tai useamman näistä:

– BTLE- tai UWB-perusteisen yksinkertaisen paikannuksen

– IR-lähettimeen + ulkoisiin kameroihin perustuva paikannus

– servon/moottorin tai muun mekaanisen laitteen ohjaus laitteen

avulla

– Ohjelmisto, joka integroi paikkaa 9dof avulla

– langaton lataus

– pikalataus esim. superkonkkaan

• Olennaista työssä on myös (työn arvosanaan vaikuttaa):

– Analysoida, mitata ja demonstroida järjestelmän viive

– optimoida käyttöaika suhteessa laitteen kokonaispainoon

Aihe 2: langaton paineanturi

kosketuspisteen ja voiman mittaamiseen

Ominaisuudet:

• käyttää joustavia resistiivisiä tai kapasitiivisia antureita

• web- tai mobiilikäyttöliittymä, jossa visualisoituna voima ja piste

Esim. sovelluskohteita:

• integroituna vaatteiseen (hiha, hanskan selkä) toteuttamaan

käyttöliittymiä

• integroituna jääkiekkokypärän sisälle mittaamaan törmäysten

voimaa

Aihe 3: Bioloid-robotti

Dynamixel AX-12A -servomoottorit

- UART

- Tehtävä uusi ohjain ja ohjelmistorajapinta

Muut ominaisuudet:

- Omat anturit

- uSD-muisti ohjelmistolle

- WLAN / BT

- Näyttö

Loppudemonstraatio testiradalla:

- Pari yksinkertaista estettä

MCU:

- Joko 8bit tai 32bit AVR

• Do not delay your start.

– We recommend that this course is taken only when the team has the intentionand dedication (and enough time) to complete the assignment during the fallsemester.

• Keep notes, documentation is your best note

• and testing functions (SW)

• In addition, the students have commented that ‘low intensity’ projects result in muchmore working hours than necessary.

• Work systematically:

– Figure out first: what is the purpose and required functions of your device?

– Split it to smaller parts and define requirements numerically

• For example: measuring range and resolution

– Find technical (HW or/and SW) solution to the requirements

– (simulate), implement and test

• When developing the device

– Do not rush, Be careful, systematic and thorough, Follow instructions

– When you get stuck, find help from

• datasheets and manuals

• Google

• course web pages

• Assistants

• More info at:

• http://www.ee.oulu.fi/research/tklab/courses/521423S/

Finally some important advice