How to connect a "touch sense" pin to a analog or digital input

Question

I'm using a motorized fader that has a "touch sense" pin (see this data sheet), which should be able to detect when someone touches the fader. I want to use it to stop the motor and switch from setting to reading mode. I'm using a Netduino Plus 2 to read the value of the potentiometer and a motor-shield to control the motor (that part is working perfectly).

I have been told that the touch sense pin is to be used to measure capacity in order to detect touching. I was hoping to just connect it to a analog input but was warned that it could potentially damage the Netduino.

How would a typical "touch sense" circuit look like when connecting to a analog or digital input? (The Netduino Plus 2 measures voltages between 0 to 3.3V).

Answer 1

Some micro controllers will detect touch, However it will not be reliable as it relies upon the electrostatic charge of the person touching the fader. That is some what random.

The capacitive sense pin on the fader is intended for connection to a Touch Circuit. This oscillates at a frequency determined by the capacitance connected to the Sense pin. Changes in the frequency caused by the additional capacitance of a person allow the circuit detect the Touch.

The other problem of touching micro pins directly is the electrostatic charge of a normal person can kill the micro. Touch Sense circuit remove this problem by providing protection. Here are some examples you can buy, but there are plenty you can build your self.