Connecting a push button, or switch
by BARRAGAN

This schematics shows how to connect a push button or switch to a Wiring binary input pin. Push buttons are open by default, when the user presses the button the switch is closed. Switches have 2 positions ON and OFF In the actual diagram the resisor r is called a pull-down since it is connected to Ground. typical value for r is 10K Ohms