mcu-flashing-debug

# MCU Flashing Debug ## Overview Use this skill to debug MCU programming failures safely. Separate connection, erase, program, verify, and reset problems before recommending mass erase, option byte changes, security unlock, or boot configuration changes. ## When To Use Use this skill when: - Firmware cannot be downloaded or flashed to an MCU. - The programmer reports connect, erase, program, verify, timeout, locked, protected, or target voltage errors. - The user mentions ST-Link, J-Link, CMSIS-DAP, OpenOCD, pyOCD, STC-ISP, WCH-Link, Nu-Link, vendor programmers, boot pins, ISP, IAP, DFU, or UART bootloader. Do not use this skill for application-level bugs after a confirmed successful program/verify/run cycle. For probe-specific debugging (OpenOCD scripts, J-Link config, adapter speed), use `openocd-jlink-stlink-debug`. ## First Questions Ask for: - MCU part number and board. - Programmer/probe and connection method. - Tool name and exact error output. - Firmware artifact path/type: ELF, HEX, BIN, IHX, UF2, or vendor package. - Whether erase, program, verify, and reset are separate steps in the tool output. - Target voltage, reset wiring, boot pins, and whether the board is externally powered. ## Workflow 1. Classify the failing step. Do not treat "download failed" as one problem. Identify connect, erase, program, verify, reset, or run failure. 1. Confirm physical and electrical basics. Check power, ground, target voltage sense, reset line, boot pins, and sig...