Kern explores what new hardware can do for Bitcoin self-custody. Bitcoin only, written in plain C: a maxCmalist signer, built to experiment, not to sell.
Kern is a research platform and intends to stay one. It is not on a path to becoming a product.
What a modern application processor like the ESP32-P4 can and cannot do for a signer: camera, display, storage, and the security hardware that comes with it.
Descriptors, miniscript, encrypted backups and signed firmware updates over SD card, implemented on real hardware, tested, and documented with their limits.
Findings, trade-offs and security limits are documented in detail in the repository, including the threat model and the risks it leaves open.
Security plan →Five off-the-shelf boards. Each one needs a MIPI CSI camera module.
| Board | Target | Display | Camera |
|---|---|---|---|
| Waveshare ESP32-P4 4B | wave_4b | 720×720 MIPI DSI | Sold separately |
| Waveshare ESP32-P4 3.5″ | wave_35 | 320×480 SPI | OV5647, included |
| Waveshare ESP32-P4 5″ | wave_5 | 720×1280 MIPI DSI | OV5647, included |
| Waveshare ESP32-P4 4.3″ | wave_43 | 480×800 MIPI DSI | OV5647, included |
| Waveshare ESP32-P4 7B | wave_7b | 1024×600 MIPI DSI | OV5647, sold separately |
| CrowPanel Advanced 7″ / 10.1″ | crowpanel | 1024×600 MIPI DSI | SC2336, included |
Kern drives both the OV5647 and the SC2336 and probes for whichever one is attached at boot, so either sensor works on any of the boards. The 4B is the one board sold without a camera: pair it with an OV5647 module carrying a DW9714 voice coil motor, which is the only combination that gets autofocus.
These boards carry an ESP32-C6 radio co-processor alongside the P4. Kern does not use it and holds it in reset mode. Users can remove or physically disable it if desired.
From an unflashed board to a working research device in a few minutes.
Any of the five boards above. All but the 4B come with a camera in the box; for the 4B, add an OV5647 module with autofocus.
The web flasher writes the latest build over USB using Web Serial, with no toolchain to install. Requires Chrome or Edge 89+.
Generate a mnemonic from dice rolls or the camera, or restore one you already have by typing it or scanning a QR code. Switch the network to testnet to experiment without risking funds.
Full user documentation is not written yet. For now, these live in the repository.
Questions, testing reports and development chat.