Custom keypad

I’ve been wanting a small, custom keypad for shortcuts while working—something compact, programmable, and fun to build. After looking through different microcontrollers, I decided on the XIAO RP2040 because of its tiny size and good support for CircuitPython .

XIAO RP2040

Mechanical switches and keycaps

A small piece of protoboard

Diodes, wires, and a USB-C cable

Holding everything together, I felt excited—and a little nervous—because this is my first time building a keypad from scratch instead of using a kit. But I’m ready to give it a try.

Day 3 – Soldering the Hardware
I started soldering the mechanical switches onto the board. It took longer than expected because the layout was tight, and the wires kept getting in the way. I also soldered the diodes for each switch to avoid ghosting.
After that, I connected all the rows and columns to the XIAO. It wasn’t the cleanest solder job I’ve done, but it worked—and that felt like a win.

Day 4 – First Firmware Test
I flashed CircuitPython onto the XIAO RP2040 and wrote a simple test script to detect button presses.
The moment I saw the first key register in the serial monitor, I actually said “Yes!” out loud. Seeing hardware and software cooperate for the first time always feels magical.
A few keys didn’t register at first—turned out to be two bad solder joints, which I reflowed.

Day 5 – Adding Key Functions
I mapped each key to something useful: copy, paste, undo, and save. I also added a layer function so I could toggle between shortcuts for work and shortcuts for gaming.
It’s a small thing, but pressing a button I built and watching my PC respond instantly felt amazing. It's like the keypad has come to life.