MPR121 Hookup Guide
CONTR IBUTORS:
TONI_K
MPR121 Overview
If you are interested in adding the ‘magic’ of touch to control your
electronics project, a capacitive touch sensor might be the way to go. This
hookup guide will show you how to use the MPR121QR2 sensor.
The MPR121QR2 is a capacitive touch sensor controller that makes it very
easy to integrate capacitive touch sensing into your project. It
communicates via I C, and works by measuring the capacitance of twelve
electrode points. When an object comes close to the electrode connector,
the measured capacitance changes. This signals the MPR121 that
something has touched a ‘button’. The IC is also capable of driving LEDs or
basic GPIO functionality on electrode pins 4 through 11, giving you a lot of
freedom for setting up your project. The sensor works from 1.6V to 3.3V.
The sensor isn’t very current-hungry, drawing only around 29 µA when
sampling every 16 milliseconds.
Materials
To work through this tutorial, you are going to need one of the three
versions of the MPR121 sensor:
• MPR121 Capacitive Touch Sensor Breakout Board
• Touch Shield
• MPR121 Capacitive Touch Keypad
You will also want a soldering iron, some hookup wires and a
microcontroller capable of I C communication. For our examples, we will be
using an Arduino Uno. You will also need some kind of material to act as a
capacitive sensing surface (also known as an electrode, which is not to be
confused with the character Electrode). Generally, aluminum foil works well.
However, you could also use coins, conductive paint, or copper tape.
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