US Patent 10126340 Method and apparatus to measure self-capacitance using a single pin

A method may include controlling a first switch to charge a reference capacitor to a first voltage level by applying a first voltage. The method may also include receiving a first analog signal from a touch sensor electrode at an input of an Analog to Digital Converter (ADC) and converting the first analog signal to a first digital value provided at an output of the ADC. In certain embodiments, the method may additionally include controlling a second switch to charge the reference capacitor to a second voltage level by applying a second voltage, receiving a second analog signal from the touch sensor electrode at the input to the ADC, and converting the second analog signal to a second digital value at the output of the ADC. The method may further include detecting a touch to the touch sensor device based on the first digital value.