STM32MP15x USART/UART Default Pins

[Otavio Borges]

Is stated on STM32MP157 datasheet's boot mode table that the MPU can be booted through UART:

– USART2/3/6 and UART4/5/7/8 on default pins

Nevertheless, I wasn't able to find which are the default pins for the UART interfaces, on the datasheet or reference manual. Where can I find those? STM32MP15-DISCO schematics uses UART4 pins PG11 and PB2 routed back to the Serial/USB bridge, are those UART4 by default?

GPIOx_AFRH/L reset value is 0 for all ports, and no UART pin is selected on AF0.

[MWoło.2]

Hi Otavio,

I think You should rather check in the reference manual on which GPIO ports STM32MP1 can be booted, the source doesn't matters.

[Otavio Borges]

Hey @Michał Wołowik​ ,

Thanks, but didn't find mention of which GPIOs are usable on boot, on reference or datasheet. For some inputs is easy to assume, since there's only one pin option, e.g. FMC and USB.

But for UART/USART there are multiple mux possibilities, couldn't find on reference or datasheet where those are allocated on boot.

[MWoło.2 · Accepted solution]

On link

https://www.st.com/resource/en/application_note/dm00389996-getting-started-with-stm32mp151-stm32mp153-and-stm32mp157-line-hardware-development-stmicroelectronics.pdf

You will find on section 10.1.3 Boot mode

[Otavio Borges]

Missed that AN 🙂

Thanks @Michał Wołowik​ ​