MPR121 touch sensor module

Introduction

MPR121 touch sensor module is a kind of capacitive touch keyboard plate controlled by MPR121. It outputs the signal that the keys received form of IIC. The control principle and control mode are widely used in function modules of the key control in devices of household appliances (like washing machine, induction cooker etc.), MP3 player, remote control and mobile phones. MPR121 touch sensor module collects, saves and transmits data through the MPR121 IC, which increases the induction sensitivity. As the operating voltage of MPR121 is 3.3V, it can carry out IIC communication with a control board whose operating voltage is also 3.3V. In addition, a SI5902DC chip and its pilot circuit is added to the MPR121 module to make sure the MPR121 module can work under 5V, and communicate with a control IC that support 5V, thus expanding the range of application of MPR121 module.

Note: the connection method varies when it is connected to different control board that works under different voltage. You are advised to connect carefully in light of the silk-screen instruction on the PCB. The 3.3v power supply should be connected to MPR121 module when it communicates with a 5v control board. (for more detailed information, please refer to chapter Ⅳ)