MPR121 - RTurala/Sonoff-Tasmota GitHub Wiki
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 capacitance sensing settings
- AN3890 MPR121 capacitance 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 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:
Generally available types of breakout boards
