PROJECT 4 - RESET (RESTART) PI
Objective: implement a hardware reset facility (without having to disconnect or switch off the 5V supply)
Uses: no software
You will need: 2-way 0.1" header and connecting leads, momentary contact switch, soldering iron and solder
When you have shutdown your Pi, it is not possible to restart it again without removing the 5V supply and then reconnecting it. This solution allows you to restart your Pi without removing the power lead or otherwise switching off the supply.
Pi boards have an unpopulated 2-way header, identified as explained below, that can be connected to a switch that when closed momentarily restarts the Pi from whatever state it was in - even shutdown. Each section below shows the location of the header for a variety of Pi versions.
A video by Alex Eames shows how to fit the header. Comments about the video might indicate that using this feature might invalidate warranty but the feature is explicitly explained in the Raspberry Pi archives here.
Model B Rev 2: header labelled P6.
Pi 2 Model B+ and Model 2: header labelled RUN located between the GPIO header and display connection.
Pi 3 Model B: header labelled RUN located between the GPIO header and USB socket.