From 59cd29a5e1b9a8f13dbd3d23c04fcf25aca98081 Mon Sep 17 00:00:00 2001 From: xRuffKez Date: Wed, 11 Nov 2026 21:10:28 +0100 Subject: [PATCH] Document flashrom usage with CH341 on Linux Added detailed instructions for using flashrom with CH341 on Linux, including steps for probing, reading, and writing flash memory. --- hardware-recovery/PROGRAMMER_REFERENCE.md | 79 +++++++++++++++++++++++ 1 file changed, 79 insertions(+) diff --git a/hardware-recovery/PROGRAMMER_REFERENCE.md b/hardware-recovery/PROGRAMMER_REFERENCE.md index 67271f9..15848b1 100644 --- a/hardware-recovery/PROGRAMMER_REFERENCE.md +++ b/hardware-recovery/PROGRAMMER_REFERENCE.md @@ -72,6 +72,85 @@ Only after the tool reports a byte-for-byte match should you unplug the CH341 pr NeoProgrammer's labels can vary slightly by release, but the required operation order does not: **three stable reads → build → full-chip erase → blank check → program → internal verify → full readback → tool verify**. NeoProgrammer describes the same backup/erase/write/verify capabilities in its [software overview](https://neoprogrammer.org/). +### Linux with flashrom and CH341 + +The [Fedora hardware test record](TEST_RESULTS.md#fedora-44-ch341-recovery) documents +a successful recovery with this procedure. It is limited to the tested +`5E 40 17` / 8 MiB SFDP setup; other IDs or layouts require separate validation. + +Follow the electrical checks in this reference and the +[main recovery guide](../README.md#failed-camera-hardware-recovery). Install flashrom with +`sudo dnf install flashrom` and cc2camera through the +[Python installation instructions](../docs/INSTALLATION.md). The documented test used cc2camera v0.9.0 (commit +`28fae6d9a0ea5a703144ded4c4b241e52614cf01`). If using a virtual +environment, use its command prefix in place of `cc2camera` below. Keep all +commands in a new working directory and close other programmer applications. + +First probe without requesting a write: + +```sh +flashrom -p ch341a_spi -VV +``` + +In the tested setup, the `Generic unknown SPI chip (RDID)` probe returned +`id1 0x5e, id2 0x4017`. Although flashrom had no named profile for the part, +SFDP detected an `SFDP-capable chip` with a capacity of `8192 kB`. Continue only +if these values agree; do not force a similar chip definition. + +Read the complete flash three times without moving the clip: + +```sh +flashrom -p ch341a_spi -c "SFDP-capable chip" -r cc2-camera-1.bin && +flashrom -p ch341a_spi -c "SFDP-capable chip" -r cc2-camera-2.bin && +flashrom -p ch341a_spi -c "SFDP-capable chip" -r cc2-camera-3.bin +wc -c cc2-camera-1.bin cc2-camera-2.bin cc2-camera-3.bin +cmp cc2-camera-1.bin cc2-camera-2.bin && cmp cc2-camera-1.bin cc2-camera-3.bin +sha256sum cc2-camera-1.bin cc2-camera-2.bin cc2-camera-3.bin > original-SHA256SUMS.txt +``` + +Each file must contain exactly **8,388,608 bytes**. Both comparisons must succeed +and all three hashes must match. Copy the dumps and checksum file to a separate +drive, then run `sha256sum -c original-SHA256SUMS.txt` there. Every entry must +report `OK` before continuing. + +Build the camera-specific image using all three reads: + +```sh +cc2camera build-image cc2-camera-1.bin --confirm-read cc2-camera-2.bin --confirm-read cc2-camera-3.bin +(cd cc2-camera-1-cc2-recovery && sha256sum -c SHA256SUMS.txt) +``` + +Stop if the build or checksum verification fails. The generated `FLASHING.txt` +may contain a Bus Pirate/`COM11` template; do not use it unchanged with a CH341. +Before writing, make another full read and require it to match the original: + +```sh +flashrom -p ch341a_spi -c "SFDP-capable chip" -r cc2-camera-before-write.bin && +cmp cc2-camera-1.bin cc2-camera-before-write.bin +``` + +**The next command erases/programs flash.** Run it only after the comparison +succeeds and the external original backup has been checked: + +```sh +flashrom -p ch341a_spi -c "SFDP-capable chip" -w cc2-camera-1-cc2-recovery/cc2-camera-recovery.bin +``` + +flashrom erases/programs the required blocks and performs full-chip verification +by default. Do not disable verification, use force options or change protection +bits to bypass an error. After successful verification, read the whole chip +again and compare it with the recovery image: + +```sh +flashrom -p ch341a_spi -c "SFDP-capable chip" -r cc2-camera-readback.bin && +cmp cc2-camera-1-cc2-recovery/cc2-camera-recovery.bin cc2-camera-readback.bin +sha256sum cc2-camera-1-cc2-recovery/cc2-camera-recovery.bin cc2-camera-readback.bin +``` + +The byte comparison must succeed and both hashes must match. Only then unplug +the programmer, remove the clip and reconnect the camera to the powered-off +printer. After reassembly, power on the printer and check the video feed. + ### Alternative: flashrom with a Bus Pirate The generated `FLASHING.txt` also contains a `flashrom` command for the Bus Pirate. Unlike the NeoProgrammer workflow, it writes only the regions reported as changed and deliberately does not enable programmer-supplied target power.