Introduction

Making an interactive lamp through the use of capacitive touch, Raspberry Pi, python, Arduino, and NeoPixels.

YouTube

YouTube: https://www.youtube.com/playlist?list=PLgAD2y-6wgwoK8elS6MGACtj486-vvLzR

Set Up

I am using a Raspberry Pi 2, but you should be able to use almost any version of the Raspberry Pi without issue. I have the project folder on my Pi's Desktop, but you can clone it where you like. Most of the code is in the examples/ folder. You might need to install the capacitive touch library I'm using: https://github.com/adafruit/Adafruit_Python_MPR121

Commands I would use to set up the Pi environment:

sudo apt-get update
sudo apt-get install build-essential python-dev python-smbus python-pip git

cd ~/Desktop
git clone https://github.com/cwalk/CapacitiveTouchLamp.git

cd CapacitiveTouchLamp/
sudo python setup.py install

To run the code:

cd examples/
sudo python cap.py

For the Arduino, just upload the sketch found at CapacitiveTouchLamp/capacitive_touch_lamp/capacitive_touch_lamp.ino

Cron job

What I did was setup a cron job to run my launcher.sh script everytime my Pi reboots (I move this script to the Pi Desktop). This makes it easy because all I have to do is add power to the Pi, and the project starts working after the Pi boots. Now I made launcher.sh run on reboot, but all this shell script does is navigate to my project directory, and run sudo python cap.py. Please feel free to just set up a cron job to run sudo python cap.py instead.

sudo crontab -e

And add @reboot sh /home/pi/Desktop/launcher.sh at the bottom.

Launcher.sh should look something like this:

cd /home/pi/Desktop/CapacitiveTouchLamp/examples
sudo python cap.py

Make sure you give launcher.sh permissions to run.

For more help, check out: https://www.raspberrypi.org/documentation/linux/usage/cron.md and http://www.instructables.com/id/Raspberry-Pi-Launch-Python-script-on-startup/

How the Code works

Basically the cap.py file is always running, thanks to the cron job. This listens for a capacitive touch from the sensor. If we get one, we generate a random number, depending on which Pin was detected. That number spins off 2 threads: 1 will play the audio file associated with the generated number, and the other will send a serial communication to the Arduino, that corresponds to the audio file being played.

Meanwhile, the Arduino, which is connected to the Pi through Serial, recieves that and will play a lighting animation that correlates to the audio file, with precise timing to the length of the audio file.

My code uses pins 0, 4, 5, 8, and 11 for sensing touch from the MPR121 capacitive touch sensor.

Circuit Diagram

Here is the circuit diagram I made.

Pi -> MPR121 Capacitive Touch sensor:

3.3V -> VIN
GND -> GND
SCL -> SCL
SDA -> SDA

Hardware:

Arduino -> NeoPixel:

5V -> 5V
GND -> GND
Pin 6 -> Data In

My code uses pins 0, 4, 5, 8, and 11 for sensing touch from the MPR121 capacitive touch sensor.