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bootloader on usart1 not working on stm32h747

PShad.2
Associate

hi,

i have a custom board with stm32h747xih6. i am trying to boot the device from usart1 on pins PA9/PA10 with no success. booting from usart1 on pins PB14/PB15 is working fine but requires new layout. jtag works fine too.

when trying boot from PA9/PA10, pin PB15 was tied high/floating (tried both ways), still no success.

i have recreated this problem on the stm32h474-disco kit with the same results.

is it possible to boot from pins PA9/PA10, or is there a problem with this IC?

ragards,

pavel

2 REPLIES 2
Imen.D
ST Employee

Hello @PShad.2​ ,

Thanks for reporting this issue.

It should worked as described in the AN2606:

0693W00000LwQwuQAF.jpgMay be you should check if there is a remap of those pins.

When your question is answered, please close this topic by choosing Select as Best. This will help other users find that answer faster.

Imen

When your question is answered, please close this topic by clicking "Accept as Solution".
Thanks
Imen

I have had a simliar problem with my own design, which is based on the STM32H747-disco connection of the SWD. I am almost inclined to believe that the problem is with the VCP of the MB1441B board (aka ST Link V3-Set) and neither the bootloader nor the MCU itself. The reason: when I use the integrated ST-LINKV3E_SWD connection then I am able to start the bootloader, which shows the protocol version 3.1. Note that this integrated debugger is connected to the same pins, (PA9 and PA10) via 22 Ohm resistors, so I do not believe that this is a pin remapping or pull up / pull down resistor issue. Despite that, how can you remap pins without even connecting to the chip via a bootloader in the first place?

So for my next design (this PCBA is now for the trash as the MCU is not recovearble) I may need to use a USB connection such as in the Arduino (DFU?) and/or an integrated ST-LINKV3E_SWD module.