A minimal controller sporting a RP2040 chip with all the 30 GPIO pins broken out – designed by Technoblogy.
KBD.news Published June 10, 2022
Another RP2040-based controller, this time in a different form factor and with open source. (Attention! This one has no USB connector!)
So @techmech_'s tweet lead me to a new controller designed by David Johnson-Davies aka technoblogy.
This breakout board is referred to as both Minimal RP2040 and Technoblogy RP2040 Board – according to the silkscreen.
David has a detailed post on the design and construction process, and he published the Eagle files here.
The first thing you may notice is that it doesn't have an on-board USB connector. This may or may not be a problem depending on your keyboard design.
Many boards, especially those with one-piece classic layouts, have USB daughterboards and extension cables making it possible to position the connector further from the controller.
If you're about to build something like that, an on-board connector would be in the way, and you needed as much GPIO pins as possible, this controller board may come in handy. (It's also narrower than a Pi Pico: only 15.24mm.)