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Welcome to

EQ2430/EQ2440 Android Lecture

March 21, 2012

Per Zetterberg

School of Electrical Engineering

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The project course goes Android!

• Display : plots and text.• Microphone.• Loudspeaker.• Magnetometer measurements.• WiFi RSSI measurements.• Send data using WiFi.• Accelerometers.• Touch screen.• Camera

Features used in our projects:

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FrameWork• FrameWork is a java project (program) in

Eclipse.• FrameWork is a Android 2.2 project that runs

(at least) on HTC Desire and Samsung S3. • FrameWork is a generic skeleton which can

be used as the starting point for many student projects (including yours!).

• FrameWork has an object StudentCode which is where you implement your prototype.

• Application name: StudentFrameWork (Change this)

• Creators: Martin Ohlsson and Per Zetterberg

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FrameWork: User interface

PlotView:

Graphs and/orCamera picture

TextView:

Textual output.

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Downloading FrameWork

Go to

EQ2440 web (KTH social) => Android support

Download: FrameWork_empty.zip

”empty” because most StudentCode functions are empty ….

or almost empty.

Unzip and move the code to workspace directory.

Do “file->import->”existing project into workspace”->

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StudentCode (i.e your code)Parameters:useSensors, loggingOn, logSound, useCameraGUI,useMessaging, messageServer, processInterval, introText, messageGroups, StudentMessage (class)

useSensors (bitfield): “xor” the followingGPS,CAMERA,CAMERA_RGB,SOUND_OUT,SOUND_IN,WIFI_SCAN,ACCELEROMETER,MAGNETIC_FIELD,PROXIMITY,TIME_SYNC, PROXIMITY,LIGHT,SOUND_IN,CAMERA, GYROSCOPE

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Called by StudentCode 1(3)sound_out(short[] buffer, int length): Send data to DAC=>loudspeaker (somewhat stochastic latency).

message_out(StudentMessage message): Send message to all the other phones.

message_out(StudentMessage message, String groupIdString): Send message to the phones in group defined by “groupIdString.

streaming_buffer_out(short[] buffer, int length, String groupIdString): Send buffer of int16 to the phones in group defined by “groupIdString”.

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Called by StudentCode 2(3)set_output_text(String text): Set the text too be displayed in TextView.

plot_camera_image(Canvas plotCanvas, byte[] image, int imageWidth,int imageHeight, int width, int height): Display a camera image.

plot_camera_image_rgb(…): Display color …

write_string_on_logfile(String): No ”\n” or ”;”.

load_sound_file(String fileName) + play_sound_file(int loop): Repeatedly plays the wav-file specified by fileName. No timing gitter (loop=-1 means forever)stop_sound_file(): Stops the above.

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Called by StudentCode 3(3)

save_rgb_frame_on_file(String filename,byte[] frame,int width,int height,boolean append) : Saves an RGB picture (=frame) on file.

public byte[] read_rgb_frame_from_file(int image_number, String filename) : loads an RGB picture (=frame) from file.

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Defined by StudentCode: Called by FrameWork 1(2)init(): Do all your initialization.start(): Called when menu button ”start” is pressed.stop (): Called when menu button ”stop” is pressed.message_in(…) Received message from other phone. gps(…) …… position estimatemagnetic_field(…) …… magnetic field measurementlight(…) : …. Light intensity (lux) event (trigger when changed)proximity(…): Proximity state event (trigger when changed)accelerometer(…) accelerometer measurementprocess(), Periodic processing with interval set by

processInterval parameter. The processInterval parameter can be changed during runtime.

You fill these functions with code!

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Defined by StudentCode: Called by FrameWork 2(2)gyroscope(…) gyroscope measurementsound_in(…) … sound input sampleswifi_ap(…) ... signal strength of surrounding WiFi APsscreen_touched(…) position eventstreaming_sound_in(…) buffer of samples (int16) received from other phonecamera_image(…) image received from camera (black and white)camera_image_rgb() image received from camera (color)plot_data(): Screen update.

All are inputs exceptplot_data!

You fill these functions with code!

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Your code structure

public void init() { … set parameters initialize}

public message_in () { … process … save}

public void process() { … heavy calculationsset_output_text(s)}

camera_image_rgb() { … save latest imagenew_image=true;

plot_data(Canvas plotCanvas, {… present results}

Data structuresalgorithm state

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The GUI

“Greeting message”

introText

Start FrameWork App-> calls init()

Start

Press menu button

Start() is calledSensors switched +on etc.

Stop

Press Start

set_output_text(String text): Set the text too be displayed in TextView.

plot_data(Canvas plotCanvas,…)

Press menu + Stop

stop() is called

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Threads (internals)“Parent thread”: Indirectly calls init().studentProcessThread: Calls process(). ipListenerThread: Calls message_in()guiTriggerThread: Renders what you provide with set_output_text() and plot_data(). t1: Calls sound_in(…)wifiScanThread: calls wifi_ap(…)ipSoundListenerThread: calls streaming_buffer_inFrameWork implements OnRecordPositionUpdateListener:

Calls gps()FrameWork implements SensorEventListeneraccelerometer(), magnetic_field(), light(), proximity()FrameWork extends Activity: sreen_touched()streaming_sound_in(…) buffer of samples (int16) sent from other phone

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How communication between phones works 1(2)• A Linux computer connected to internet acts as a server (the

address of which is given by messageServer).

• When FrameWork starts, it contacts the server and asks for the ip adress of one of the other phones in the project (a project is defined by the projectName string e.g. ”yellow”).

• The phone then contacts that phone and gets a list of all other phones in the project.

• When one phone calls message_out(message) the message is sent to all other phones in the project.

• The other phones receives the message through a call of message_in (”callback”).

• The message is of type StudentMessage and contains the fields that you decide.

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How communication between phones work 2(2)• Second form of message_out: message_out(message, groupIdString)

• Where groupIdString defines a group of users e.g. ”data_receivers” which should receive the message.

• Which groups exist ? You define the groups with the ”messageGroups” parameters.

• When FrameWork starts, it asks the user which group the phone belongs to.

• When sending buffers of int16 use the following version: streaming_buffer_out(buffer,length, groupIdString)

• This data is received through: streaming_buffer_in( buffer, int length, senderId)

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How to use communication between phones 1(2)Set useMessaging = true;

If you need groups:•String temp[] = {"MICROPHONE","SPEAKER"};•messageGroups = temp;Otherwise:•messageGroups = null;

In both cases:•messageServerType = LINUX_MESSAGE_SERVER; •messageServer = "192.168.0.68";•Define StudentMessage (defined in StudentMessage.java)

Which message group do this phone belong to ?:messageGroups[myGroupID]

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How to use communication between phones 2(2)public class StudentMessage extends StudentMessageBase {// Add your message fields here// do not use primitive types that begins with lower case letters Float dummy=0.0F; /* Example of student message data */ Boolean is_sync_message; Boolean is_distance_message; Float value1; Float value2; Float value3; Float value4;}

Same definition in all phones!

message_out(my_message,SPEAKER”);In transmitter

public void message_in(StudentMessage message){If (sync_message) correlation=value1;…

In receiver(SPEAKER)

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Logging on file 1(2)

• loggingOn = true;• Logs measurements from all active sensor except

camera • … and you own debug messages:

write_string_on_logfile(“correlation=“+correlation)• Creates a measurement file called sensorlogYYYYMMDDHHMM.csv on the SDCARD.

The measurement file is ASCI with measurents in clear text.

How retrieve file:method1: Mount SDCARD on PC.methods: Using our matlab functions.

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Logging on file 2(2): matlab utilities

• Copy file to PC-harddisc (matlab command)copy_file_from_sdcard_to_working_directory.m • Obtain the data from the log-file into matlab:get_log_data_from_FrameWork.m• Extract data from some certain sensors:

• extract_acceloremeter_from_log_data.m,• extract_sound_from_log_data.m, • extract_magnetic_from_log_data.m

• Other sensors:• Do it yourself.

Problem: SOUND_IN fluds measurement log.

Solution: logSound=false;

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Test harnessPurpose: Test implementation of math-intensive functions/algorithms in an isolated and repeatable way.Method:Run your matlab- and java- (with android environment) -implementations side by side with exactly the same input .How?•Matlab produces data, and pushes it on the sdcard•FrameWork includes a function called ”test_harness()”.•Inside this function

the data can be read from the sdcard,

the function to be tested is called,and the results are saved on the sdcard.

•Matlab then pulls the data from sdcard.•Finally, the results from the matlab- and java-implementation are compared.What do I need to do ?The example test_harness_example.m shows how to automate the process. This code can be used as a starting point, however, you need to customize the code to the function you are going to test.

All, non-trivial functions should be tested like this.

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State-machine and functionspublic void process() {{

switch(State) {case START:

res1=func1(arg1,arg2); res2=func2(signal1);

State=WAITIING;break;

case WAITING:sync=func3(arg1,res2);if (sync) {State=RUNNING; transmit(signal2)}

else {State=WAITING; transmit(signal1)};break;

case RUNNING:.....

}write_string_on_logfile("State="+State);

}

public void message_in(StudentMessage message){

switch(State) {case WAITING:....

}

Functions that can be tested against matlab implementation using harness

Example of debugging method.

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Using sound (input)

time1536 samples 1536 samples 1536 samples

useSensors = SOUND_IN | SOUND_OUT;

sampleRate = 22050;

sound_in(long time, short[] samples, int length)

sound_in(long time,…

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Sound output 1(2)sound_out(short[] buffer, int length)

sound_out(short[] buffer, int length)

Variable gaps

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Sound output 2(2)

load_sound_file("bing.wav"); play_sound_file(-1);stop_sound_file();

wavwrite(y,44100,16,’bing.wav’);copy_file_from_working_directory_to_sdcard(‘bing.wav’);

Only in init(), process() and stop()

Constant gaps

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RGB Camera: Image formatvoid camera_image_rgb(byte[] image, int width, int height)

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1

3

image={r0,g0,b0,r1,g1,b1,r2,g2,b2,…}

w

1w

1wh

Byte 0-255

1w 12 w

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RGB Camera: File format

File format (”.rec”):

width height r0,g0,b0,r1,g1,b1,….

Frame

Frame 1 Frame 2 Frame N

Always stored in /sdram/recordings

Filename (example): video201303181626.rec

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RGB_Camera: GUI

Alt1: useSensors = CAMERA_RGB; useCameraGUI=true;

Start Rec Play Stop

void camera_image_rgb(byte[] image, int width, int height)

Log to file: /recordings/videoyyyyMMddHHmm.rec

Browse for file and playback: Calls camera_image_rgb(byte [] image, int width, int height)

Stop recording

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RGB_Camera:No GUI

Alt1: useSensors = CAMERA_RGB; useCameraGUI=false;

Camera runs continuously.

void camera_image_rgb(byte[] image, int width, int height)

….is called….

save pictures to file using call:

save_rgb_frame_on_file(String filename,byte[] frame,int width,int height,boolean append)

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Load RGB picture from file

int read_rgb_frame_width_from_file(int image_number, String filename)

int read_rgb_frame_height_from_file(int image_number, String filename)

byte[] read_rgb_frame_from_file(int image_number, String filename)

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Display picture (example)

plot_data(Canvas plotCanvas, int width, int height) {

if((latestRGBImage != null) && ((useSensors & CAMERA_RGB) == CAMERA_RGB)){

plot_camera_image_rgb(plotCanvas,latestRGBImage,ImageWidth,imageHeight,width,height);

};};

Updates≈10Hz

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Pictures Matlab interface

list=list_video_recordings_on_sdcard(time0)

copy_video_recording_file_from_sdcard_to_working_directory(filename)

rgb_video= extract_video_recording_from_file(filename);

image(rgb_video.frames{1}.rgb)

create_video( filename, rgb_video )

rgb_video.frames{1}.rgb A 768x432x3 matrix(:,:,1)=red (:,:,2)=green (:,:,3)=blue

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Display pictures another way

void plot_data(Canvas plotCanvas, int width, int height) {

plotCanvas.drawLine(… plotCanvas.drawRect(……}

http://developer.android.com/reference/android/graphics/Canvas.html

More info:

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ZXING QR decoder

“ZXing (pronounced "zebra crossing") is an open-source, multi-format 1D/2D barcode image processing library implemented in Java”

To test:useSensor=CAMERA_RGB; uncomment code in StudentCode.java between ”zxing start color” and ”zxing stop color”

Direct camera towards QR code

Source code located under ExternalSrc.com.google.zxing

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Give your App a unique identity• Right click on project folder (Top level folder named

FrameWork) within the Package Explorer window• Select Android Tools/Rename Application Package• Add a unique name after FrameWork like:

se.kth.android.FrameWork.GroupRed2013• Press Finish in the Refactoring window• Confirm update of Launch Configurations• Voila, you now have a separately installable version of

your app!

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Phone configuration

Samsung S3”Settings” -> ”developer options” -> tick ”USB debugging””Settings” -> ”Security and lock screen” -> tick ”Unknown sources”

HTC Desire”Settings” -> ”Applications” -> ”Development” -> tick ”USB debugging” ”Settings” -> Applications” -> tick ”Unknown sources”When connecting to PC: choose ”charge only”

Wifi (both):http://www.lan.kth.se/eduroam/phones/phones_mobile_guide.html

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Assignments1. Write letter ”C” and ”D” in plot_data using the “drawRect”

function of Canvas. Plot the letters using a system of bitmap fonts that you may design yourself.

2. Switch between the letters of your group color every two seconds. 3. Record a sound and play it with two echoes.4. Make an app running on two phones. When one of the phones is

moved, the other phone beeps.5. Make an app which captures pictures and classifies them as

mostly red, green, blue or yellow. The result is displayed in the text window.

6. Make an app which sends audible pulses from one phone. Run the app on two phones (with distinguishable pulses). Make another app which estimates the difference between the sample-clocks of the two phones by listening to the aforementioned pulses.

7. Make a test-harness for a non-trivial algorithm which is relevant for your project.

Deadline : Mid-term evaluation.

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Hints• Start command line prompt in windows 7: press

windows_button+”r”, then run “cmd.exe”.• Android software developers kit:

http://developer.android.com/sdk/index.html• Killing tasks. Download and install “Advanced Task

Killer Free (ATKF)”. To kill e.g. “StudentFrameWork” open ATFK press “StudentFrameWork” until a new menu appears where you can select “Kill”

• Error message: “ActivityManager: Warning: Activity not started, its current task has been brought to the front” => Change a single line in the source files code and try again.

• Error message:FrameWork_empty_130319] Re-installation failed due to different application signatures => Do “uninstall se.kth.android.FrameWork” from command line prompt.