A controlled shutdown button

The Raspberry Pi should always be shut down correctly to avoid the SD card being corrupted (by losing power while performing a write operation to the card). This can pose a problem if you don't have a keyboard or screen connected (you might be running an automated program or controlling it remotely over a network and forget to turn it off) as you can't type the command or see what you are doing. By adding our own buttons and LED indicator, we can easily command a shutdown and reset, and then start up again to indicate when the system is active.

Getting ready

You will need the following equipment:

• 3 x DuPont female-to-male patch wires
• Mini breadboard (170 tie points) or a larger one
• Push-button switch (momentary close)
• General-purpose LED
• 2 x 470 ohm resistors
• Breadboard wire (solid core)

The entire layout of the shutdown circuit will look as shown in the following figure:

The controlled shutdown circuit layout

How to do it...

1. Create the shtdwn.py script as follows:

#!/usr...