Capacitive Touch Sensor Module (TTP223)

The TTP223 detects the change in capacitance when a finger touches or comes close to the pad, so it works even through a thin layer of plastic, glass or wood. It runs from 2–5.5 V and provides a single digital output that connects directly to a GPIO pin, with an LED on most boards showing the touch state. Two solder jumpers set its behaviour: momentary or toggle mode, and active-high or active-low output. It is a simple way to build hidden switches, touch lamps, control panels and sealed buttons with no moving parts to wear out.