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Theo Arends edited this page Jul 17, 2018 · 12 revisions

MPR121 I2C Proximity Capacitive Touch Sensor Controller

  • 12-button or touch pad I2C controller
  • Driver supports up to 4x MPR121 controllers (= 48 buttons per ESP8266)
  • Electrodes can be covered with adhesive paper and adhesive plastic foil for labeling and symbols
  • Break-out and touch button PCBs ~ 2,- € at AliExpress
  • Break-out PCB ~ 8,- $ at Adafruit

Technical Data from the manufacturer

Wiring breakout boards

Breakout ESP8266
VCC/VIN +3.3VDC
GND GND
SCL GPIO SCL
SDA GPIO SDA
IRQ NC

I2C address selection

Connect the ADD(R) pin/pad to one of the following pins/pads:

Address ADD(R)
0x5A NC
0x5B +3.3VDC
0x5C GPIO SDA
0x5D GPIO SCL

Tasmota configuration

Compile Tasmota with #define USE_MPR121 uncommented in user_config.h

The driver will detect the I2C addresses of the MPR121s automatically. The MPR121 chip (or breakout board) must be connected to the ESP8266 and the I2C GPIO pins must be configured:

I2C GPIO configuration

Generally available types of breakout boards

Adafruit 12-Key Capacitive Touch Sensor Breakout - MPR121 Touchpad front Touchpad back Break-out front Breakout back

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