Touch Shield Test Report

Touch Shield Test Report

This board use the MPR121 as the main IC,This IC can connect 12 pads,8 of the 12 pads can be usd as the second functions(driving the leds),The supply voltage vary from 1.71v to 3.6v. The circuit can be as low as 29uA at the sampling rate of 16ms,The IC communicatie with the MCU Through interrupt or I2C.

Picture 1 The IC

We used 9 pads on our board as input,This board can be placed on the arduino board conveniently.

Picture 2 Touch shield board

1. instructions

This board use the 3.3v voltage of the arduino board,it communicate with the arduino board through I2C,the voltage of the MCU’s IO is 5V, in order to compatible with the Tocuth shield board voltage , the board used 2 MOS FET to solve the problems.

SDA------A4

SCK------A5

interrupt------D2.

2. test procedure

software platform: arduino

test code:see the attachment

code procedure:

init the I2C

init MPR121

enable the interrupt

handle the interrupt process,send the data through UART

notice: The interrupt handle function cannot work with the condition more than two key push down at the same time. 

Picture 3 after the initialize

Picture 4 The interrupt function send the data to the PC when the key is pressed