[Alan Anderson]

Connect it between the ground and signal pins of a Digital I/O. The Digital Sidecar's built-in pullup resistor will provide a logic 1 on the input when the switch is open, and closing the switch will give a logic 0. There is a Common terminal on the switch; wire that to ground. Use either the Normally Open or the Normally Closed terminal as the signal, depending on whether you want the switch to close or to open when activated.