HARDWARE HEAVEN

While we’ve mostly covered the Raspberry Pi here in its role as a computer, there’s a duality to it: It’s as much a hobbyist hardware platform as it is mini PC. Thankfully, the Pi 4’s hardware shift has not affected its GPIO pins, which are laid out in the same way as the whole range, from Pi Zero up, so the entire world of Pi HATs is available to those open to experimentation. Whether you want to add a dedicated LCD, e-ink, or TFT display, add arcade control to your emulation box, upgrade its audio output with a dedicated DAC, or give yourself a convenient platform for electronics tinkering, there’s something for you.

We wouldn’t call any HAT absolutely essential, but something that adds an actual hardware power switch to the Pi should be high on your list, particularly if you’re running headless, because powering down a Pi by yanking out the USB connector is a tremendously bad idea for your data. A SHIM (which, charmingly, stands for “shove hardware in the middle”) is a great choice for this, because it won’t interfere with any HATs you’ve placed on top of it. Pimoroni’s OnOff SHIM (around $8) is a great choice as long as your case gives room for you to reach its small momentary button—it does also offer breakout pins for a button of your own. All it takes is a little one-line software command to install the clean shutdown script and protect your Pi from data loss.

Of course, you don’t have to use a SHIM—those pins are yours to play with. If you want to write your own shutdown script, and wire the right pair of pins to a button or switch of your own, you can.