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RPowe.9.306
RPowe.9.306
Associate III
July 21, 2020
Question

No Response From Bootloader over USART

  • July 21, 2020
  • 3 replies
  • 888 views

My employers have made a custom board based on STM32WB55. I have developed some software but need to program this to flash. I have access to USART1 and BOOT0 pin. (I also have access to SWD, SWCLK, JTDI, JTDO). I thought that pulling BOOT0 high would enable me to talk to the bootloader over the USART but I get no response. I have tried the ST programmer and have also tried talking from my C# app by sending 0x7F at various baudrates to see if I at least get an ACK. Any help please.

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3 replies

HRadt.1
HRadt.1
Associate III
July 21, 2020

Maybe you fell for the same trap that I did: The Bootloader only works with Pins PA9/PA10 as TX/RX pins. Not with PB6/PB7.

RPowe.9.306
RPowe.9.306Author
Associate III
July 23, 2020

Thanks.

This is the sort of gotcha that should have a warning in big bold letters but never does!

Actually have Rx on PA9 and Tx on PB6

HRadt.1
HRadt.1
Associate III
July 23, 2020

It defininitely should ... especially since without bootloader access, a lot of the steps needed for production are way more complicated (depending on your usecase).

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