OttoPi: Otto DIY like biped robot for Raspberry Pi see github pages Power ON/OFF Button Power ON button GPIO 3 -> SW -> GND Shutdown button GPIO 4 -> SW -> GND GPIO 21 -> R(1K ohm) -> LED -> GND dtoverlay=gpio-shutdown,gpio_pin=4 dtoverlay=gpio-poweroff,gpiopin=21,active_low=1