Momentary NO switch installed on a Raspberry Pi 2B. ... When the system enters the halt state and we push the button, ... The stm32 would then switch the p-fet feeding the Rpi 5v supply off.

Both the Raspberry Pi Pimoroni OnOff SHIM and Pimoroni Button SHIM with 5 x tactile, right-angle push buttons are priced at $6.95 and both are in stock as of the current time.

Most of the circuit is dedicated to level shifting from the 5v Amiga 500 to the 3.3V Raspberry Pi. ... Two buttons, one used to switch disks, ... push each bit.