bootloader on usart1 not working on stm32h747

[PShad.2]

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

[Imen.D]

Hello @PShad.2​ ,

Thanks for reporting this issue.

It should worked as described in the AN2606:

May 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

[Clem1]

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.