The Raspberry Pi is a very versatile tool for any tinkerer. Lately there has been several projects where I wanted to include a Raspberry Pi, but did not have access to the correct voltage power supply. This turned me onto the idea of constructing a "hat" for the Pi that would serve as a power supply with a wide input voltage range.
Before going to a local maker festival I brought my earlier keyboard project to a more usable state. The goal was a sort of interactive conversation piece.
This is an older reverse engineering project I did. I wrote about it for Rana Makerspace, and decided to make another post with more of the technical details.
When using a microcontroller to read something with lots of inputs, like a keyboard, there aren't enough IO pins to give one to every input. You have to turn to tricks like multiplexing.
