RasPi is a great platform -- but doesn't have any power management as bought. And, running a Linux kernel means that files are open almost all the time. Turning off power is risky.

Per Jeremy Cook it's pretty easy to do this. I bought switches like he suggested, rated at 12v but the leds light up with 5v just fine. These switches have a built-in resistor on the LED, so the wiring to the switch is just 3 wires: ground, gpio3, and led-signal.

  • A momentary switch between header pins 5 and ground
  • An LED between (arbitrarily) pin 10 (gpio 15) and ground (with resistor, as needed)
  • This in /boot/config.txt where the "gpio15" line matches your chosen wiring
# shutdown via button

# led on gpio15

and wonder-of-wonders -- IT WORKS!