4.3.2 Touch Sensors

QT1 Xplained Pro have four touch sensors that can be used: One slider, one wheel, and two buttons. The sensor design on the Mutual Capacitance board and the Self Capacitance board are a bit different due to the method used for the touch sensing. For mutual capacitance, both X- and Y-lines from the microcontroller are used to sense the capacitance between the X and Y sensors. The sensors are placed on top of each other on the inner layers of the PCB. Self capacitance use only Y-lines from the microcontroller and only one layer is used to place the sensor in the PCB. In this case, the self capacitance of the sensor is measured to calculate touch.