Even with careful execution, issues can arise. Below are the most frequent problems and their solutions.
| Symptom | Likely Cause | Manual Fix |
|--------|-------------|-------------|
| Device not responding after patching | Incorrect offset applied (e.g., endianness mismatch) | Re-dump, compare checksums with a known-good xyw58cdt9av7_patched.sha |
| Patch appears successful but reboots every 10s | Watchdog not fully disabled | Manually verify location 0x3E10 contains three NOPs (0x90), not 0x00 |
| Serial output shows garbage | Baud rate patch failed | Re-apply the arithmetic correction at 0x7F2A: change 0x0A to 0x0C at 0x7F2C |
| Flash verification fails | Weak connection on SOIC8 clip | Clean pins, retry with lower speed (flashrom -p ft2232_spi:spispeed=512) | xyw58cdt9av7 manual patched
Using your programmer:
flashrom -p ft2232_spi -r original_dump.bin
Or via OpenOCD:
openocd -f interface/stlink.cfg -f target/stm32f1x.cfg -c "init; dump_image original_dump.bin 0x08000000 0x10000; shutdown"
Manual patching bypasses all safety checks. Incorrect writes can brick the device permanently. Always back up the original firmware before making changes. Even with careful execution, issues can arise
flashrom -p ft2232_spi -w patched_firmware.bin
Or via SWD:
openocd -f interface/stlink.cfg -f target/stm32f1x.cfg -c "flash write_image erase patched_firmware.bin 0x08000000"