1. This is the branching board of Freescale MPR121QR2. MPR121 is a capacitive touch sensor controller driven by I2C interface. The chip can control up to twelve individual electrodes as well as an analog thirteenth electrode. The MPR121 also has eight LED driver pins. When these pins are not configured as electrodes, they can be used to drive LEDs.
2. There are four jumpers at the bottom of the board, all of which are set (off) by default. The address jumper will ground the add pin, which means that the default I2C address of the chip will be 0x5A. If you need to change the address of the chip (by shorting the add to another pin), make sure to turn on the jumper first. Jumpers also connect SDA, SCL and interrupt pins to 10K pull-up resistors. If you do not need pull-up resistors, you can turn on the jumpers by cutting off the traces that connect them.
3. There is no regulation on the board, so the voltage provided should be between 2.5 and 3.6V DC. The VREG pin is grounded through a 0.1uF capacitor, which means you cannot operate the mpr121 in low supply voltage mode (1.71-2.75vdc) unless you modify the circuit board.
Product size: 30 * 20 * 3mm/1.18*0.78*0.11\'\'
Please allow 1-3mm differs due to manual measurement.
Due to the different display and different light, the picture may not show the actual color of the item. Thanks for your understanding.
1 X MPR121 Breakout V12 Keyboard Development Board