A (much) better Pro Micro
The Bit-C is a microcontroller daughterboard featuring the Atmel ATmega32U4, designed for DIY keyboard enthusiasts. It features a sturdy through-hole USB-C connector that is more rugged than a standard USB micro B. It's only 1mm thick, so it sits slim and low. The Bit-C ships with the Atmel DFU bootloader, which is smaller and less finicky than the default Caterina bootloader. 100% of Bit-C units are exhaustively tested before shipping, ensuring you're spending your time building, not debugging. Best of all, it comes in white!
100% Pro Micro compatible
The Bit-C is a drop-in replacement for any Pro Micro MCU, including the Elite-C. With 1-1 GPIO pin parity, firmware builds don't need to be changed in order to swap in a Bit-C. The Bit-C is shipped with the lightweight Atmel DFU bootloader, making flashing with QMK a breeze. VBUS detection & backdrive protection are implemented for split keyboards, and a 500mA resettable fuse is included for protection.
Tri-mode LED
The built in white LED shows power status by default, and can be set to 3 different brightnesses using GPIO controls. Don't like the built-in LED? Turn it off. Use it to show layer or caps lock status. Bright, dim, and off modes allow for maximum flexibility.
Bit-C Comparison Table
| Bit-C PRO RP2040 | Bit-C AVR 32U4 | |
|---|---|---|
| CPU architecture | RP2040: ARM Cortex M0+ | ATmega 32U4: AVR |
| CPU clock | Dual core @ 133MHz | Single core @ 16MHz |
| GPIO Voltage Level | 3.3V | 5V |
| Flash size (program storage) | 4MB on-board | 16kB on-chip |
| RAM size (variable and data storage) | 264kB on-chip | 2.5kB on-chip |
| QMK firmware support | ✅ | ✅ |
| Arduino IDE support | ✅ | ❌1 |
| Micropython support | ✅ | ❌ |
| Circuitpython support | ✅ | ❌ |
| Electrically compatible with Bit-C PRO RP2040 | ✅ | ❌2 |
| Electrically compatible with Bit-C AVR 32U4 | ❌2 | ✅ |
1 The Bit-C AVR 32U4 can be used with Arduino IDE, but requires flashing a new bootloader.
2 The Bit-C PRO RP2040 and Bit-C AVR 32U4 cannot be "mixed and matched", as they use two different electrical voltage levels. For example, if building a split keyboard such as the SNAP, both Bit-Cs must be the same model. Boards connected over TRRS must also use the same MCU.
See it in the wild
Check out community-posted images sourced from the nullbits Discord server, Reddit, and more.
Included in the box
- Bit-C MCU
Resources & downloads
OS Compatibility
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