Yahboom sells an AI module for robots and classrooms: Kendryte K210 dual-core RISC-V at 400 MHz, 8 MB of SRAM, OV2640 or GC2145 camera, 2-inch 240×320 touchscreen, microSD, no battery, no Wi-Fi. Hardware AES and SHA-256 are compute accelerators, not a Secure Element. Nobody loads Recover onto it: there is no vendor OS to sign. The K210 boot ROM, like a Pi’s, stays closed.
Krux, free firmware, has supported it since March 2024. The box often includes a 32 GB card, a USB reader, and a PH2.0 adapter for an optional thermal printer. You flash with the Krux installer, check the hash, sign PSBTs via QR or microSD. Sparrow, Nunchuk, Liana, Bull Bitcoin speak that language. Miniscript and Taproot live in the firmware, not in the plastic. Ordering a vision module does not write “hardware wallet” on an invoice.
By default, power-off means no seed. You can persist an encrypted mnemonic in flash or on SD: then the Yahboom becomes a vault again, on an MCU with no authenticator, and stealing the device is no longer stealing empty plastic. Dice or the camera for entropy, firmware re-checked, no gaze while the words are on screen, remain the real ritual. A look, human or lens, bypasses the K210 the way it bypasses SeedSigner.
Fits if
Low-cost Bitcoin air-gap, a multisig leg, no soldering, no purchase that looks like a vault.
Keep in mind
Bare MCU: an equipped physical attacker is not the model. Firmware to verify at every flash. Encrypted stateful = the secret returns to the device. Availability of a vision module, not of a Bitcoin product.
Related incidents
- 2018– — Clones and marketplaces
The first security ritual is commercial: who sold you the object, and what does attestation say on first plug-in?