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Prototype
Multiplexed Macropad
Custom input device, PCB design, HID firmware
3x3 macropad built around a Pro Micro with multiplexed keys.
Designed a simple 3x3 macropad using Cherry MX switches and a multiplexed diode matrix. The PCB mounts to a plate with 3D-printed keycaps and uses an Arduino Pro Micro for control.
Firmware is minimal but functional: the device identifies as USB HID and sends key events over serial rather than running a full keyboard OS like QMK. Future revisions should integrate the MCU on-board, add encoders and analog inputs, improve mechanical robustness, and move to QMK or a wireless stack.
Highlights
- 3x3 Cherry MX matrix with diode multiplexing
- Arduino Pro Micro control with USB HID output
- 3D-printed keycaps and plate mounting
Tools and Methods
- PCB design
- Cherry MX switches
- Diode matrix
- Arduino Pro Micro
- 3D printing