*This application is tested only with Samsung Galaxy GT-i5700 Spica (rooted Android 2.1 OS, i570EXXJD1 Baseband version).
The transmitter circuit uses Microchip's dsPIC33FJ16GS504 for the analog-to-digital conversion of the input signals on two channels. The processed data on the dsPIC are then transmitted to the phone (for waveform display) via the LMX9838 bluetooth SPP module.
specs/ranges:
- time per division: {5us, 10us, 20us, 50us, 100us, 200us, 500us, 1ms, 2ms, 5ms, 10ms, 20ms, 50ms }
- volt per division: {10mV, 20mV, 50mV, 100mV, 200mV, 500mV, 1V, 2V, GND}
- analog input (depends on external pre-amplifier configuration): {-8V to +8V }
The source codes for the bluetooth communication is based on Bluetooth Chat example from http://developer.android.com. That example contains three java source files. And, I've completely copied the "DeviceListActivity.java", which is used for searching remote bluetooth devices. Then I've modified the "BluetoothChatService.java" to use only the RFCOMM Client functions, and used the well-known UUID "00001101-0000-1000-8000-00805F9B34FB" for the Bluetooth RFCOMM/SPP.
For the plotting of waveforms, I'm using SurfaceView object to draw on its canvas. This tutorial found on www.helloandroid.com helps me a lot for this task: "How to use canvas in your android".
The rest of the job mainly involves porting of my previous Python S60 script to JAVA language. It was too painful on my side, because I had to convert a single script file to multiple java + xml source files! Nonetheless, it was a good experience for me on learning the Android SDK (JAVA programming).
Project source codes for Android and dsPIC (with APK and HEX) :
AndroidBluetoothOscilloscope.zip
Electronicslab.ph forum link : Android Bluetooth Oscilloscope
Here are some interesting projects that are also based on the Bluetooth Chat example:
Bluetooth Controlled Model Car
SPRIME
Special thanks to:
Samdroid Forum for the customized/rooted firmwares for our Spica.
Tipidcp Spica users for sharing their tips and experiences with this android phone.
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#edit (10-15-2010)
Here's now my circuit. Nothing special on it, all are based on existing circuits.
*If you prefer to change the input range via the op-amp preamp, the computation is located on the "adc.xmcd" file.
*You can use other SPP bluetooth modules aside from LMX. (accdg to manufacturer, it's already obsolete)
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#edit (9-14-2011)
It's almost a year now, and yet some people are still interested in this project (considered to be obsolete). So I've decided to place the source repository also on Google Code site. You can either Browse or use git to have your own local copy:
git clone https://code.google.com/p/android-bluetooth-oscilloscope/
See also the Changes, if you want also to learn on how to modify the code. I've started the first 'commit' with a simple "hello world" from the SDK project template. And then changes were made until the desired final oscilloscope application is achieved.
