MPR121 – Capacitive Touch Sensor Breakout

Description

Small breakout board based on the Freescale MPR121QR2 chip, a capacitive touch sensor controlled via the I²C interface. The chip can individually control up to 12 electrodes and a maximum of 8 LEDs (when not configured as electrodes). On the bottom of the board there are 4 jumpers (pads with traces), all closed by default. One jumper connects the ADD pin to ground, so the chip’s I²C address will be 0x5A. The jumpers also connect the SDA, SCL, and IRQ pins to 10 kohm pull-up resistors. The breakout does not have a voltage regulator, so the supply voltage must be between 2.5 and 3.6 Vdc. Weight: 3 grams.

Documentation and useful links

• Schematic
• Eagle Files
• Datasheet (MPR121QR)
• Example Code (ATmega328)
• Hookup Guide
• Freescale’s Product Page (for Application Notes, etc.)
• Bildr Tutorial
• GitHub