A capacitive touch sensor detects a touch from human body with little or almost no force required. It can be used as an input device, replacing the needs for a mechanical switch.
This is a breakout board for MPR121, a capacitive touch sensor from Freescale, driven by I2C protocol. The board can control up to 12 touch electrodes. 8 of them can be configured to drive LED when they are not used as electrodes.
On one side of the board, there is a 6-pin header for power and I2C communication with a controller. On the other side, there is a 12-pin header for connection to the electrodes.
Underside of the board, there are 4 jumpers which are closed by default. The ADD jumper ties the ADD pin to the ground so that the default I2C address of this board is 0x5a. You can change the address by connectiong ADD to a different pin, however, you need to open the ADD jumper by cutting the connecting trace. The other 3 jumpers, namely SDA, CL and IRQ connects the SDA, SCL and IRQ pins to a 10k Ohm pull-up resistors. If you do not need this, you need to open the jumpers as well.
You can use any conductive object as input to this sensor. This includes household objects such as fruits, vegetables and aluminium foils. When you touch those objects, the sensor detects change in capacitance and this is communicated back to the I2C bus.
All pin-outs are marked on the board. Header pins are included but not soldered.
