The 60th Bitaxe Town Hall, hosted as always by WantClue, featured a special guest this week: Schnitzel, the creator of the Libre Board—a fully open-source control board for Bitcoin miners. Originally from Switzerland and now based in Virginia, USA, Schnitzel is a software engineer whose passion for heat reuse and open hardware has led to one of the most exciting developments in the Bitaxe ecosystem.
From S9s to the Libre Board
Schnitzel’s journey into Bitcoin mining began around 2020 with Antminer S9s. His primary motivation wasn’t just mining Bitcoin—it was heat reuse. He used miners to heat garages, an Airstream trailer, a hot tub, and eventually his house. But he quickly ran into a frustrating reality: controlling stock miners for custom setups was nearly impossible with closed-source control boards.
This frustration pushed him toward the 256 Foundation’s open-source ecosystem and ultimately inspired the Libre Board, funded by a grant from the foundation.
What Is the Libre Board?
The Libre Board is designed as a powerful, open-source replacement for the proprietary control boards found in miners like the Bitmain S19 or S21. Its design philosophy is refreshingly pragmatic:
- Reuse existing standards: USB-C for hashboard communication, Qwiic (I²C) for sensors and displays, and standard Raspberry Pi HATs for expandability.
- Modular compute: Built around the Raspberry Pi Compute Module 5 (CM5), using the standard 200-pin interface. Users can choose anything from a basic 1GB module to a 16GB multi-core—or even third-party RISC-V alternatives.
- All-in-one controller: Unlike stock boards that need an external Raspberry Pi for complex tasks, the Libre Board integrates everything. You can run mining firmware, a Bitcoin full node, home automation (like Home Assistant), and custom logic on a single board.
Hardware Highlights
The Libre Board is packed with features that make it incredibly versatile:
- 4x USB-C ports for hashboards, expandable via standard USB hubs. This means you can mix and match different hashboard models—S19, S21, even Bitaxe Raw—all on one controller.
- 12–24V DC input with onboard voltage regulators, making it compatible with car batteries or direct solar panel connections.
- M.2 slot for NVMe SSDs—perfect for running a full Bitcoin node.
- USB 3, Ethernet, Wi-Fi/Bluetooth (via CM5), HDMI, and MIPI display port.
- 4x 12V fan headers with full RPM control.
- Qwiic connector for daisy-chaining temperature sensors, pumps, displays, cameras, and more.
- Pi HAT compatibility, SD card slot, real-time clock battery, and an RGB status LED.
Machina: The “Linux Kernel” of Mining
Schnitzel also discussed Machina, the open-source firmware being developed by the 256 Foundation (led by Ryan). He described it as the “Linux kernel” of mining—universal, adaptable, and designed to support any hashboard, not just one manufacturer.
Support for the Bitaxe Raw already exists, and support for Bitmain S19 J Pro, S19 K Pro, and S21 is actively being added.
AI-Assisted Reverse Engineering
One of the most fascinating parts of the discussion was how the team is using AI to reverse-engineer proprietary firmware. By sniffing the I²C communication between stock firmware and hashboards, they can rapidly generate drivers for Machina—sometimes in as little as 30 minutes.
This approach opens the door to advanced features that current firmware simply doesn’t offer:
- Per-hashboard power tuning and voltage control
- Dynamically disabling boards to reduce power draw (ideal for solar or battery setups)
- Custom ramp-up/ramp-down curves managed by AI for specific use cases
The Doomaxe: Mining Meets Gaming
To demonstrate the Libre Board’s potential, Schnitzel built the Doomaxe—a fully portable, battery-powered, open-source Bitcoin miner. It made its debut at a Las Vegas mining conference and turned more than a few heads.
The build combines a Libre Board, Bitaxe Raw hashboard, battery pack, fan, SSD, and touchscreen. But the name came from something even cooler: Schnitzel successfully ran the classic video game Doom on a small OLED screen connected via Qwiic. Hence, Doomaxe—Doom meets Bitaxe.
It’s a fun demo, but it also represents something bigger: what Schnitzel believes is the first fully open-source, battery-powered Bitcoin miner (hardware and software), with the only closed component being the ASIC chip itself.
The Future: Heat Reuse as a Household Appliance
Schnitzel’s ultimate vision goes beyond hobbyist mining. He sees a future where Bitcoin mining is integrated into everyday appliances through heat reuse:
Imagine buying a water heater or home heater at a hardware store for a fraction of the normal price—because it contains a miner. The homeowner gets cheap heat, while the manufacturer recoups the cost through Bitcoin mining rewards. Because the Libre Board is open-source, any manufacturer can produce it, enabling variants like a “Libre Board Light” or a “Max” version from different producers around the world.
Current Status and How to Get Involved
The Libre Board is currently at the prototype stage. Only two Revision 2 boards exist, and the team discovered issues with the USB controller that are being addressed in Revision 3.
Schnitzel is actively soliciting feedback on use cases before Rev 3 is finalized to ensure all necessary ports and features are included. Once Rev 3 is tested, the goal is for any producer with a pick-and-place machine to begin manufacturing. Interested producers and community members are invited to reach out for a potential small test run.
If you’re interested in the future of open-source Bitcoin mining, the Libre Board is one of the most exciting projects to watch.
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