Afpy Camp 2012

The Afpy Camp at my house is now over, and I had a great time as usual. This year we decided we'd play with Raspberry Pi and Arduino boards, so it was less Python-centric than usual.

After a few basic LED projects, we tried (and failed) at making a LCD screen work but it seems that there's a problem with the Leonardo board. Overall that board seems to be quite buggy compared to the Uno.

I then worked with Alain on making a DC Motor run, using a transistor and a battery pack for the motor. It took us quite some time but we managed to make it work. The goal was to design a board to control two engines to run an old RC Nikko car I stole from my son's room. The board we planned to build was supposed to send a negative or positive current into the engines, so the car could move forward, backwards and on the sides.

But all this work became overkill because sunday, Laurent brought a shield that does all this job (and more). It's a shield you can plug on an Arduino Uno and that can control 4 DC engines and 2 servos.

So all we had to do is to plug it in the car, and write a small program based on the AFMotor library.

We then added a bluetooth chip so we could control the car from an Android phone using a Bluetooth terminal.

Here's the program uploaded in the Arduino:

  #include <AFMotor.h>
  #include <SoftwareSerial.h>

  AF_DCMotor motor(4, MOTOR12_64KHZ);
  AF_DCMotor motor2(2, MOTOR12_64KHZ);
  SoftwareSerial mySerial(14, 15);

  void setup() {

  void loop() {
  int value =;

  if (value != -1) {

      if (value==49) {;

      if (value==50) {;

      if (value==51) {;

      if (value==52) {;

      if (value==53) {;

      if (value==54) {;

Pretty basic stuff: when we hit '1' on the phone -- char 59, the car moves fowards, etc.

Here's a video of the car in motion:

The next step would be to create an Phone application with a real UI. Maybe based on the accelerometer. Ideally, I want to create a Boot to Gecko (Firefox OS) application that does this. That's a good excuse to play with this new system.

And ultimately, I'd like to add a webcam and build a small Python web server so people can take control of the car over the web. But that's another story.

Thanks a lot to & Jon for all the hardware !