This Raspberry Pi Pico-Powered Compact Keyboard PCB Breaks Unused GPIO Out to 3.5mm Jacks
Reddit user "stewartd430" has designed a Raspberry Pi Pico-powered compact keyboard, complete with an expansion port for adding extra hardware to the microcontroller's general-purpose input/output (GPIO) pins.
"I designed a keyboard PCB for the Pico," Stewart explains of his project, which builds on earlier efforts including a simpler 20-key macro keypad driven by the same Raspberry Pi Pico board with RP2040 microcontroller. "65 percent layout, with 15 added macro keys and rotary encoder."
The PCB is designed for use with Cherry MX mechanical key switches, or pin-compatible equivalents, and includes the rotary encoder as an additional input for volume or other analog controls to the upper-right.
A key feature of the design is in its expandability: Two of the RP2040's general-purpose input/output (GPIO) pins are left free by the board, and rather than going to waste are broken out to a pair of 3.5mm jacks — alongside 5V and ground connections — for easy expansion.
"There are a few things i want to adjust (the space bar is just a hair to far to the left for the 1.25u Alt key to fit) before I release anything," Stewart says of his plans for the board. "Also Its an irregular size, so cases might have to be custom made. I haven't looked into cases much."
"I'm planning to 3d print a router template, so I can hollow out a piece of black walnut I've been sitting on for a while. Needing a custom case is probably the biggest problem with selling these boards, but it would definitely be cool to see what people come up with to really make it theirs. I think you could get real creative with the addressable LEDs above the top row of keys. I'm still not sure how i want to handle them."
More details are available in Stewart's Reddit thread.