the question is probably pretty dumb, but I just can't get my head around it:
I need to detect change of a touch sensor (TTP223 IC), which gives a constant signal
when it's touched and drops to ground when it's not touched.
I tried a simple RC circuit which gives me a signal when it's touched, which slowly
drops to ground again. When the sensor is not touched any more the capacitor discharges
and gives me a negative signal. Can I detect that with a GPIO pin too? Or will that
actually even damage the raspberry? Or is it possible to turn the negative voltage into
a positive? Tried that using transistors, diode bridges (rectifier), but couldn't figure it
out. Rectifier would work if I'd had positive and negative source, but I only have
positive and ground. Hope someone can give me a hint... Thanks!