Sovol Zero#

The Sovol Zero ships a forked Klipper — host klippy/ plus MCU src/ — on Sovol’s all-in-one Zero control board: an Allwinner H616 Linux host plus an STM32H750 mainboard that doubles as the USB-CAN bridge, and a separate STM32F103 CAN toolhead. Everything else in the stack — Moonraker, Mainsail, Katapult, gs_usb, crowsnest, KlipperScreen — is already stock upstream. Only Klipper is forked, so that’s the only thing you have to move.

This section takes the machine fully onto upstream Klipper: host plus both MCUs on one pinned commit, app and bootloader, with no vendor bytes left in the firmware. The one vendor layer that stays afterward is the OS image, and replacing that is optional.

The machine, layer by layer#

Read the four-layer model once for the reasoning; then use these as the component library.

• Hardware — the system map (host + three CAN MCUs), the toolhead pinout and SWD header, and the board’s hardware facts: dead ports, absent-on-late-units sensors, camera limits.
• MCU firmware — building both apps and Katapult from one pinned commit, the one-time SWD flash of the toolhead, and the no-SWD mainboard route over USB-Katapult.
• OS — vanilla Armbian on the stock eMMC, offline preseed, the one device-tree property that separates this board from a real CB1, and recovery.
• Application — the KIAUH stack, translating the config to mainline eddy/tap, plugins, calibration, and proven add-ons.

Assemble your path#

The runbooks are the entry points. Pick the one that matches your situation and it forwards you through the layers above in the right order:

• Over stock firmware — the printer works and you migrate in place.
• With an eMMC reader — clean-slate build from a blank eMMC.
• Recovery — a machine that won’t boot, or a bad flash to roll back.

Key facts#

• Mainboard (STM32H750) — build it as an STM32H743. The app lives at 0x8020000, past the internal flash. Built as MACH_STM32H743 it reaches that offset from a stock target with no patch, and H743 defaults to the validated 400 MHz clock — the H750 target builds the same offset but defaults to 480 MHz, which this board isn’t validated at. Flash over USB-Katapult; the textbook 32 KiB offset bricks the stock bootloader.
• Toolhead (STM32F103) — Katapult at the standard 8 KiB offset, Klipper app at 0x8002000. The vendor Katapult is request-only and can’t be recovered over CAN, so the toolhead needs one SWD flash to install a CAN-capable mainline Katapult; after that it flashes over CAN — no probe, no opening the head.
• Mainboard Katapult, no SWD — replace it with mainline Katapult by building a Katapult deployer and flashing it through the stock bootloader over USB. A bootloader from an unknown prebuilt is exactly what you don’t want on the one MCU you can’t easily recover.
• Eddy probe (LDC1612) — use software I2C on mainline; the F103 hardware I2C2 throws START_NACK without the vendor’s STM32F1 errata workarounds. On master it does tap probing.

Status#

Verified end-to-end on one printer: host and both MCUs entirely on upstream Klipper, no vendor bytes left in the firmware. Corrections and additions — other probes, other board revisions, the H750-native build route — are welcome via a PR.

Credit#

The most complete Zero-specific mainline resource is asnajder/zero-config; cross-checking against it shaped several choices here. The sibling Rappetor/Sovol-SV08-Mainline project (same H616 + CAN family, different mainboard MCU) was the closest existing reference.

Disclaimer#

Reflashing MCU firmware can brick hardware. The mainboard is the USB-CAN bridge — a bad flash takes the whole CAN bus down. As long as Katapult survives you can re-flash over USB; only a corrupted bootloader forces SWD on the buried mainboard. Take your own SWD dump first — that is your rollback. Proceed at your own risk.