The Grove - Tilt Switch is the equivalent of a button, based on SW-200D, which is a two balls type single direction tilt sensitive trigger switch. It is used as a digital input. Inside the tilt switch is a pair of balls that make contact with the pins when the case is upright. Tilt the module over and the balls don't touch, thus not making a connection. It is wired to the SIG line, NC is not used on this Grove.