Welcome to
EQ2430/EQ2440 Android Lecture
- a crash course in Android
March 22, 2011
Per Zetterberg
School of Electrical Engineering
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The project course goes Android!
Features used in our projects:
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Display : plots and text.
Microphone.
Loudspeaker.
Magnetometer
measurements.
WiFi RSSI measurements.
Send data using WiFi.
Accelerometers.
Touch screen.
Cool!
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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.
• 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/or
Camera picture
TextView:
Textual output.
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StudentCode (i.e your code)
Parameters:
useSensors, loggingOn, useMessaging,
messageServer, processInterval, introText,
messageGroups, StudentMessage (class)
useSensors (bitfield): “xor” the following
GPS,CAMERA,SOUND_OUT,SOUND_IN,WIFI_SCAN,
ACCELEROMETER,MAGNETIC_FIELD,PROXIMITY,TIME_SYNC
, PROXIMITY,LIGHT,SOUND_IN,CAMERA
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Called by StudentCode
sound_out(short[] buffer, int length): Send data to
DAC=>loudspeaker.
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.
set_output_text(String text): Set the text too be
displayed in TextView.
plot_data(Canvas plotCanvas, int width, int height):
Make a drawing in PlotView.
plot_camera_image(Canvas plotCanvas, byte[]
image, int imageWidth,int imageHeight, int width,
int height): Display a camera image in PlotView.
write_string_on_logfile(String): No ”\n” or ”;”.
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All are
inputs
except
plot_data!
You fill
these
functions
with code!
Defined by StudentCode:
Called by FrameWork
init(): Do all your initialization.
process(), Periodic processing
message_in(…) Received message from other phone.
gps(…) …… position estimate
magnetic_field(…) …… magnetic field measurement
light(…) : …. Light intensity (lux) event (trigger when changed)
proximity(…): Proximity state event (trigger when changed)
accelerometer(…) accelerometer measurement
sound_in(…) … sound input samples
wifi_ap(…) ... signal strength of surrounding WiFi APs
screen_touched(…) position event
streaming_sound_in(…) buffer of samples (int16) received
from other phone
camera_image(…) image received from camera
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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_in
FrameWork implements OnRecordPositionUpdateListener:
Calls gps()
FrameWork implements SensorEventListener
accelerometer(), 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)
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A Linux computer connected to internet acts as a server (the
address of which is given by messageServer).
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When FrameWork starts, it contacts the server and asks for
the ip adress of one of the other phones in the project (a
projec t is defined by the projectName string e.g. ”yellow”).
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The phone the contacts that phone and get a list of all other
phones in the project.
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When one phone calls message_out(message) the message is
sent to all other phones.
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The other phones receives the message through a call of
message_in (”callback”).
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The message is of type StudentMessage and contains the
fields that you decide.
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How communication between
phones work 2(2)
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Second form of message_out: message_out(message,
groupIdString)
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Where groupIdString defines a group of users e.g.
”data_receivers” which should receive the message.
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Which groups exist ? You define the groups with the
”messageGroups” parameters.
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When FrameWork starts, it asks the user which group
the phone belongs to.
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When sending buffers of int16 use the following
version: streaming_buffer_out(buffer,length,
groupIdString)
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This data is received through: streaming_buffer_in(
buffer, int length, senderId)
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How to use communication
between phones
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Set useMessaging = true;
If you need groups:
String temp[] = {"MICROPHONE","SPEAKER"};
messageGroups = temp;
Otherwise:
messageGroups = null;
messageServerType = LINUX_MESSAGE_SERVER;
messageServer = "192.168.0.68";
Define StudentMessage.
Which message group do this phone belong to ?:
messageGroups[myGroupID]
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Logging on file
• loggingOn = true;
• Creates a measurement file called
sensorlogYYYYMMDDHHMM.csv on the SDCARD.
• 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
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Other sensors:
Do it yourself.
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Test harness
Purpose:
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,
All, non-trivial
functions should
be tested like
this.
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.
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State-machine and functions
int State=START;
public void process() {
{
Functions that can be tested
against matlab implementation
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:
.....
Example of debugging
}
write_string_on_logfile("State="+State);
method.
}
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Assignments
1. Write letter ”A” and ”B” in plot_data.
2. Switch between the letters of your name every two
seconds.
3. Send a dot between two phones i.e. one user pushes
the screen on one phone, and a dot appears on the
other users screen on the place where the user put
her/his finger.
4. Record sound and play it again – but delayed 10
seconds.
5. Record sound on one phone and play it on the other.
6. Make a test-harness for a non-trivial algorithm which is
relevant for your project.
Deadline : April 11.
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Downloading FrameWork
Go to
EQ2430 web => project, android and usrp support =>
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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Tips
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Start command line prompt in windows 7: press
windows_button+”r”, then run “cmd.exe”.
The tool “adb” is located at C:\android-sdkwindows\tools\
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.
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Now
Lets start!
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