STM32 Bootloader • Web Serial

STM32 Web Flash

Flash a custom firmware binary to a connected STM32 running the factory UART bootloader. Plug in, connect, and program.

Serial connection

Disconnected

Baud rate

Bootloader auto-baud detects the 0x7F init byte.

Start address

Must be 4-byte aligned for write operations.

Firmware binary

Select a file, typically firmware.bin

Mass erase before flashing

Jump to application after flash

Auto-open console after flash

Auto-enter bootloader (DTR/RTS)

Send GPIO sequence RTS high → pulse DTR → RTS low. Wire RTS to BOOT0 and DTR to NRST. (Some browsers expose these as RequestToSend/DataTerminalReady.)

Idle

Log

Serial console

Console closed

Console baud rate

Console uses 8-N-1 (typical app UART).

Bootloader checklist

[Optional for some boards] Set BOOT0 high (or use your board boot jumper) then reset.
Connect over USB-to-UART (CDC) and select the port.
Factory UART bootloader expects 8 data bits, even parity, 1 stop bit.
Use a browser that supports Web Serial (Chrome/Edge).