This week's assignment was to make something interactive by adding a capacitive sensor. Basically we had to make and then modify a board called the "Efe" board.

 

 

The first thing to do was to assemble it and program the chip to make it work, so that we could then modify it. These pictures show the efe.charge.py file at work. The white bar increases as you move your finger closer to the copper plate in the board working as a proximity and touch sensor. The only weird thing is that when you touched the plate the bar became unstable and started to jump values. We couldn't find a way to fix that

 
   

This is the code for the microcontroller on the Efe. I tried changing the board to make the LED intensity vary as my finger approached the sensor, but the PWM pin was already used by the A-D converter. The next thing I tried was to use a timer to generate an interrupt to turn the LED on and OFF but I had some problems with the code.
 

I also tried connecting a larger surface to the sensor to sense proximity rather than just touch, that didn't work either. Finally, I made two circuits, one using the vinyl cutter and one using photoresistive materials and chemical etching. However the vinyl cut circuit wasn't working too well so I ended up using the other one. This picture shows the different Efe versions: