15 MPR121

Michael Ingraham edited this page 2019-06-14 15:07:48 -04:00

Table of Contents

• MPR121 I2C Proximity Capacitive Touch Sensor Controller
• Technical Data from the manufacturer
• Wiring breakout boards
• I2C address selection
• Tasmota configuration
• Generally available types of breakout boards

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

• MPR121 Fact sheet
• MPR121 Data sheet
• AN3889 MPR121 capacitive sensing settings
• AN3890 MPR121 capacitive sensing filtering and timing
• AN3891 MPR121 touch sensing baseline system
• AN3892 MPR121 touch sensing jitter and false touch rejection
• AN3893 MPR121 proximity sensing
• AN3894 MPR121 LED driver system
• AN3895 MPR121 serial communication
• AN4600 MPR121 Designing a Touch Panel
• MPR121 Evaluation board schematics

Wiring breakout boards

Breakout	ESP8266
VCC/VIN	+3.3VDC
GND	GND
SCL	GPIO I2 SCL
SDA	GPIO I2 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 I2 SDA
0x5D	GPIO I2 SCL

Tasmota configuration

Compile Tasmota with #define USE_MPR121 added in user_config_override.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:

Generally available types of breakout boards

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