re-hardware-io

Inspect the PCB silkscreen for TX/RX/GND labels and use a multimeter to find ground and measure voltage levels. UART TX pins show a square wave pulled high at power-on. A JTAGulator can automatically enumerate UART and JTAG pins on unknown boards.

Power off the board, clip a SOIC8 adapter onto the flash chip matching pin 1 orientation, then run flashrom -p ch341a_spi -r backup.bin with a ch341a programmer. Verify the read with -v and keep the original dump with its sha256 hash.

Garbled output usually means a wrong baud rate or swapped TX/RX wiring. Enumerate common rates starting with 115200 and 9600, ensure TX/RX are crossed and grounds are shared, and use a logic analyzer to measure the actual bit width on the TX line.

Connection failures with all-zero IDCODE typically indicate fused JTAG or enabled read protection on production boards. Try the SWD interface instead, use target-specific unlock sequences like stm32f1x unlock, or fall back to UART plus direct flash reading.

No, connecting 5V TTL signals to a 3.3V board can permanently damage the interface. Always measure the board's logic level with a multimeter first, use a 3.3V adapter, and add a bidirectional level shifter like TXS0108 for 1.8V or 2.5V targets.

Hardware extraction is the last resort after software methods are exhausted. If you already have a firmware file, unpack it directly; if you need to run it, try emulation first. Only attach to physical hardware when no firmware image is obtainable otherwise.