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Major rewrite, application notes and wiring instructions.

Rene Bartsch 2018-07-12 12:19:32 +02:00
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MPR121.md

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* Break-out and touch button PCBs ~ 2,- € at [AliExpress](https://www.aliexpress.com/wholesale?catId=0&initiative_id=&SearchText=mpr121)
* Break-out PCB ~ 8,- $ at [Adafruit](https://www.adafruit.com/product/1982)
Documentation:
* [Datasheet](https://www.sparkfun.com/datasheets/Components/MPR121.pdf)
* [AN3891](http://cache.freescale.com/files/sensors/doc/app_note/AN3891.pdf)
* [AN3892](http://cache.freescale.com/files/sensors/doc/app_note/AN3892.pdf)
* [AN3893](http://cache.freescale.com/files/sensors/doc/app_note/AN3893.pdf)
* [AN3894](http://cache.freescale.com/files/sensors/doc/app_note/AN3894.pdf)
* [AN3895](http://cache.freescale.com/files/sensors/doc/app_note/AN3895.pdf)
## Technical Data from the manufacturer
* [MPR121 Fact sheet](https://www.nxp.com/docs/en/fact-sheet/MPR121FS.pdf)
* [MPR121 Data sheet](https://www.nxp.com/docs/en/data-sheet/MPR121.pdf)
* [AN3889 MPR121 capacitance sensing settings](https://www.nxp.com/docs/en/application-note/AN3889.pdf)
* [AN3890 MPR121 capacitance sensing filtering and timing](https://www.nxp.com/docs/en/application-note/AN3890.pdf)
* [AN3891 MPR121 touch sensing baseline system](https://www.nxp.com/docs/en/application-note/AN3891.pdf)
* [AN3892 MPR121 touch sensing jitter and false touch rejection](https://www.nxp.com/docs/en/application-note/AN3892.pdf)
* [AN3893 MPR121 proximity sensing](https://www.nxp.com/docs/en/application-note/AN3893.pdf)
* [AN3894 MPR121 LED driver system](https://www.nxp.com/docs/en/application-note/AN3894.pdf)
* [AN3895 MPR121 serial communication](https://www.nxp.com/docs/en/application-note/AN3895.pdf)
* [AN4600 MPR121 Designing a Touch Panel](https://www.nxp.com/docs/en/application-note/AN4600.pdf)
* [MPR121 Evaluation board schematics](https://www.nxp.com/docs/en/data-sheet/KITMRP121EVM_SCH.pdf)
## Wiring breakout boards
| Breakout | ESP8266 |
|----------|-----------|
| VCC/VIN | +3.3VDC |
| GND | GND |
| SCL | GPIO SCL |
| SDA | GPIO SDA |
| IRQ | NC |
| ADD(R) | See [table](https://github.com/arendst/Sonoff-Tasmota/wiki/MPR121/_edit#i2c-address-table) |
### I2C address table
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
The driver will detect the I2C address of the MPR121 automatically.
The MPR121 chip (or breakout board) must be connected to the ESP8266 and the I2C GPIO pins must be configured:
![I2C GPIO configuration](https://raw.githubusercontent.com/arendst/arendst.github.io/master/media/wemos/wemos_sht30_config_marked.jpg)
## Generally available types of breakout boards
![Adafruit 12-Key Capacitive Touch Sensor Breakout - MPR121](https://cdn-shop.adafruit.com/1200x900/1982-00.jpg)
![Touchpad front](http://ae01.alicdn.com/kf/HTB1qxxWSVXXXXXNXpXXq6xXFXXXO.jpg)
![Touchpad back](http://ae01.alicdn.com/kf/HTB1j.0aSVXXXXcPapXXq6xXFXXXR.jpg)