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UART DFU mode does not work after the board has been programmed

teddyw
Visitor

‎2025-11-17 5:25 AM - last edited on ‎2025-11-17 5:36 AM by

Dear Sir,

My board is equipped with STM32G431 MCU. 

I found that the UART DFU mode of my board does not work after the flash of the MCU has been programmed. The UART DFU mode can only work with a blank MCU that have not been programmed before. I have only used the default setting in the CubeProgrammer.

I appreciate if you can give me any suggestion.

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10 REPLIES 10
darenluie
Associate II

‎2025-11-17 7:22 AM

It sounds like your application code may be changing the boot configuration or blocking the bootloader from starting. Check your option bytes, especially BOOT0 and nBOOT_SEL, and make sure the user code isn’t disabling the system bootloader. Also confirm the UART pins are free at reset. If DFU only works when the MCU is blank, it usually means the boot mode settings are being overwritten once the firmware is flashed.

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