Raspberry PI Lickometer

Touch Sensor

Datasheet for MPR121: https://cdn-shop.adafruit.com/datasheets/MPR121.pdf

Materials

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

Item	PID	Price	Quantity	-Total
Raspberry Pi 3 Model B Starter Pack - Includes a Raspberry Pi 3	3058	$84.95	1	$84.95
Adafruit Capacitive Touch HAT for Raspberry Pi - Mini Kit - MPR121	2340	$14.95	1	$14.95
Adafruit Perma-Proto Half-sized Breadboard PCB - Single	1609	$4.50	1	$4.50
Small Alligator Clip Test Lead (set of 12)	1008	$3.95	1	$3.95
Adafruit Capacitive Touch HAT for Raspberry Pi - Mini Kit - MPR121	2340	$14.95	1	$14.95
Brass M2.5 Standoffs for Pi HATs - Black Plated - Pack of 2	2336	$0.75	2	$1.50

Software

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:

dtoverlay=i2c-bcm2708

Dependencies

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

Install Python MPR121 Library

cd ~
git clone https://github.com/adafruit/Adafruit_Python_MPR121.git

Run Test Software

cd Adafruit_Python_MPR121
sudo python setup.py install
cd examples
sudo python simpletest.py

Lickometer

Contents