# Keybytes modular keyboard uses per-key RISC-V microcontrollers, open-sourced under MIT

> **Key takeaway:** Each 1U key module contains a CH32V003 RISC-V microcontroller and connects via magnetic pogo-pin I2C, allowing arbitrary keyboard layouts assembled like Lego blocks.

**Published:** 2026-10-27T13:34:43+00:00 
**Source:** Tom's Hardware 
**Category:** open-hardware 
**Canonical URL:** https://fosswire.org/news/keybytes-modular-keyboard-uses-per-key-risc-v-microcontrolle.html 

## Summary
MIT student Nathan Alspaugh (notaroomba) has released Keybytes, a fully modular mechanical keyboard project where every individual key is a self-contained unit with its own RISC-V microcontroller. The system centers on a 'Keyword' hub board with an Arm Cortex-M4, Bluetooth, and USB-C, to which users magnetically attach 'Keybit' modules measuring 19.05 x 19.05mm each. Every Keybit uses a CH32V003 RISC-V MCU and exposes pogo pins on all four sides for power and I2C communication, enabling keys to snap together in any configuration without a fixed PCB matrix.

The entire project is open-sourced on GitHub under the MIT license, including PCB designs, firmware, and mechanical files. Alspaugh estimates a full-size 110-key build with two Keywords would cost approximately $900 in components. The project reached a working state in October 2026 after beginning in March 2026, though current Keybits lack per-key RGB lighting and the GitHub repository only demonstrates two Keybits connected so far.

## Architecture and microcontroller design
- **Keyword hub:** Stacked dual-PCB design with an Arm Cortex-M4 microcontroller, Bluetooth antenna, flash memory on the top board; USB-C port, charging circuitry, and buck-boost converter on the lower board.
- **Per-key compute:** Each Keybit module runs a WCH CH32V003 RISC-V microcontroller, a low-cost 32-bit RV32EC core with embedded flash, handling individual key scanning and I2C communication independently.
- **Magnetic interconnect:** Pogo pins on all four sides of every 1U Keybit provide power distribution and I2C bus connectivity; magnetic cases allow mechanical attachment to the Keyword hub or adjacent Keybits in any orientation.
- **Switch compatibility:** Keybits accept standard Cherry MX mechanical switches; users can substitute preferred switch types following the MIT-licensed design files.
- **Form factor:** Both Keyword and Keybit modules conform to standard 1U keycap spacing at 19.05 x 19.05mm, preserving compatibility with existing keycap sets.

## Why it matters
Keybytes represents a rare fully open-hardware input device architecture that pushes per-key intelligence to inexpensive RISC-V microcontrollers rather than centralized matrix scanning. For the open-hardware community, the MIT-licensed release of PCB files, firmware, and mechanical designs provides a reference platform for rethinking human interface devices as composable, network-attached peripherals rather than fixed-layout PCBs. The project's use of commodity CH32V003 MCUs and standard Cherry MX switches lowers barriers for derivative works, though the $900 estimated cost for a full-size build and the soldering requirements will likely limit adoption to dedicated hobbyists and researchers exploring modular input paradigms.