Macro Pad

A custom wired 3x3 macro pad PCB with MX switches, an OLED display, and a rotary encoder running QMK firmware.

PCB Parts

Core electronics:

• 1x Adafruit KB2040 RP2040 Kee Boar Driver
• 1x 0.96 inch 128x64 SSD1306 I2C OLED display module
• 1x Bourns PEC11R-4220F-S0024 rotary encoder with push button
• 1x 6 mm D-shaft knob for the encoder
• 9x 1N4148 SOD-123 diodes

Keyboard parts:

• 9x Kailh Red Cherry MX-style switches
• 9x keycaps

Mounting:

• 5x M3 screws, 6 mm
• 5x M3 heat-set inserts

PCB:

• 2-layer custom PCB
• 1.6 mm thickness
• 1 oz copper
• Lead-free HASL finish
• No assembly

Firmware

QMK keyboard source lives in firmware/.

Prerequisites

Install the ARM toolchain and pipx:

brew install --cask gcc-arm-embedded
brew install pipx

Install QMK:

pipx install qmk
qmk setup

Configure the path to the firmware. Run from the repo root:

qmk config user.overlay_dir=$(pwd)/firmware

Compiling

qmk compile -kb macropad -km default --compiledb

This produces firmware/macropad_default.uf2.

Flashing

First time

To enter boot mode, hold the BOOT button, press and release RESET, then release BOOT. A drive named RPI-RP2 will mount. Drop firmware/macropad_default.uf2 onto it; the board flashes, unmounts, and restarts automatically.

Re-flashing

Switch to the BOOT layer with the rotary encoder, then press any key. The board enters boot mode and the RPI-RP2 drive mounts again — drop the updated firmware/macropad_default.uf2 onto it.

Credits

• Adafruit KB2040 PCB symbol and footprint: drewgates/kb2040-kicad