This schematic of the eight pad version shows the working of the touch wheel it is very simple and is basically the same thing eight times. The capacitor in the schematic is the human body to the ground.
The four pad version ofcourse works the same but it is only one side of the schematic.
Hey, would it be possible for me to have a look at the code? I'm working on a similar thing, but I'm a bit stuck on the code.