SPI flash dumping (CH341a)

Required once: backs up the bootloader/app (IC300) and factory data (IC301) before any modding, and produced the dumps every finding here rests on. Dumps stay local — never commit or publish them (vendor IP; .gitignore blocks *.bin). Involved enough to deserve its own page; checklist version in RE-PROCESS.md §1.

0. What you need

Black CH341a Mini Programmer (v1612-class flow below; others similar), SOIC-8 clip, multimeter, a Linux host with flashrom.
Target: core module, IC300 (boot+app) + IC301 (data), both MX25L12833F.

1. Identify the chips

Factory stickers cover the markings — peel carefully, photograph first. Confirm SOIC-8 pin 1 (dot/dimple, lower-left on both packages below) and probe VCC/GND powered on (VCC = 3.3 V on this board). The exact part name matters for flashrom -c.

2. Fix the programmer voltage (do not skip)

The black board's 3.3/5 V jumper only switches ZIF VCC. The CH341A chip itself stays on 5 V USB, so CS/MOSI/CLK idle at ~5 V even in the 3.3 V position — out of spec for 2.7–3.6 V flash (degrades/kills). Verify: plug in empty, meter GND → CS/MOSI/CLK. If ~5 V, either do the 3.3 V mod (feed CH341 VCC pin 28 from the AMS1117 3.3 V output) or use a level-shifter adapter board. Re-meter: all signals ~3.3 V before touching the device.

3. Select SPI mode

Two personalities: 1a86:5523 + ttyUSB0 = UART mode (useless here), 1a86:5512 = SPI mode (flashrom needs this). Move the P/SPI jumper, replug, confirm with dmesg (New USB device found, idVendor=1a86, idProduct=5512).

4. Permissions and containers

Couldn't open device … errno=13 = permissions. Test with sudo; make it permanent with a udev rule for 1a86:5512 (MODE="0666") + udevadm control --reload-rules && udevadm trigger.
sudo inside distrobox/toolbox is not host root for USB. Run on the host: distrobox-host-exec sudo flashrom … (or flatpak-spawn --host …); podman / docker need --privileged -v /dev/bus/usb:/dev/bus/usb.

5. Dump (read-only)

Device fully unpowered. Hold the SoC in reset if clipping in-circuit (avoids bus contention with the C6748 driving SPI); WP/HOLD pulled high.
Seat the SOIC-8 clip on pin 1 → pin 1. A slipped clip shorts rails — reseat, don't force.
Per chip, read twice to scratch files, then keep the verified copy as the canonical dump: flashrom -p ch341a_spi -c <exact-chip-name> -r ic300_a.bin (then _b).
sha256sum ic300_*.bin; cmp ic300_a.bin ic300_b.bin — must be identical; expect exactly 16,777,216 B per MX25L12833F. Third read on any mismatch. Then save one verified copy as ic300.bin (ic301.bin for the other chip). Canonical names everywhere: ic300.bin / ic301.bin.
Never -w/-E (write/erase) during backup. Writing is only for recovery with a verified dump in hand.

6. Sanity-check the dumps

IC300 starts 54 49 50 41 (TIPA = AIS 0x41504954), entropy ~6.9.
IC301 starts AILS, pattern names in clear, RIFF/WAVEs from 0x8007E0.
onlySD == 0 string-set test vs the running firmware version (see RE-PROCESS.md §2) confirms which release is flashed.

Troubleshooting

Symptom	Cause → fix
`1a86:5523`, `ttyUSB0`	UART mode → move mode jumper, replug
`Couldn't open … errno=13` (even with sudo in container)	USB not passed through → run on host (§4)
`FF…`/`00…` reads, JEDEC ID unknown	Clip seating / wrong `-c` name / chip still powered by board → reseat, hold reset, re-probe `VCC`
Signals meter ~5 V	Unmodded black CH341a → §2 before retrying

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