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Raspberry PI Lickometer

Touch Sensor

Datasheet for MPR121:


Total: $124.80 (not including shipping, about $30)


Adafruit Tutorial

Adafruit Python library

Enable I2C

Be sure to enable i2c!

raspberry menu -> Preferences -> Raspberry Pi Configuration -> Interfaces => enable I2C

see Configuring I2C

Patch for I2C

"the latest Raspbian Jessie and Stretch releases have an updated I2C driver that isn't compatible with how this library enables repeated I2C start bits. From the thread about this issue there's a workaround to enable the older I2C driver. Edit the /boot/config.txt on your SD card and add:



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

Install Python MPR121 Library

cd ~
git clone

Run Test Software

cd Adafruit_Python_MPR121
sudo python install
cd examples
sudo python