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Graduate II
April 8, 2025
Solved

bootloader for STM32G474QET6 - usable UART pins?

  • April 8, 2025
  • 5 replies
  • 798 views

I am trying to use the bootloader of the STM32G474QET6 with USART to program my microcontroller. 

I have multiple questions regarding this but the first one is more about hardware. I have found in AN2606 that for the bootloader I can only use one of three USART, as listed under :

EliazLB_0-1744100551282.png

So after this info, I can use either USART1, 2 or 3 but when I look at the pins attached and at the datasheet of my microcontroller, pins for USART3 on the MCU are not PC11 and PC10. 

EliazLB_1-1744100662917.png

The thing is on my PCB I've decided to use PB10 and PB11, and according to the datasheet, they are the pins of USART3.

So my question is pretty simple, which document is right and which should I follow ? Am I going to need to change anything ? 

Thanks for the answers !

    This topic has been closed for replies.
    Best answer by Mike_ST

    Hello,

    >> pins for USART3 on the MCU are not PC11 and PC10

     

    Mike_ST_0-1744102086837.png

     

    >> So my question is pretty simple, which document is right and which should I follow ?

    Both are right,

    >> Am I going to need to change anything

    If you want to use the bootloader on USART3, probably you'll need to switch to PC10/PC11.

    5 replies

    Super User
    April 8, 2025

    @EliazLB wrote:

    EliazLB_0-1744100551282.png

    So after this info, I can use either USART1, 2 or 3 but when I look at the pins attached and at the datasheet of my microcontroller, pins for USART3 on the MCU are not PC11 and PC10.  !


    I think what it's telling you is that you can use USART1 on PA9,10; or USART2 on PA2,3; or USART3 on PC10,11.

    If your particular chip does not provide those specific pins, then you can't use it on that chip.

    Super User
    April 8, 2025

    Hang on!

     


    @EliazLB wrote:

    but when I look at the pins attached and at the datasheet of my microcontroller, pins for USART3 on the MCU are not PC11 and PC10.  !


    Yes, they are:

    AndrewNeil_0-1744102282872.png

     

    EliazLBAuthor
    Graduate II
    April 8, 2025

    Yes thank you apparently I can't really read...

    Mike_STAnswer
    Technical Moderator
    April 8, 2025

    Hello,

    >> pins for USART3 on the MCU are not PC11 and PC10

     

    Mike_ST_0-1744102086837.png

     

    >> So my question is pretty simple, which document is right and which should I follow ?

    Both are right,

    >> Am I going to need to change anything

    If you want to use the bootloader on USART3, probably you'll need to switch to PC10/PC11.

    EliazLBAuthor
    Graduate II
    April 8, 2025

    So the simple answer is I need to use pins indicated in AN2606 ?

     

    Super User
    April 8, 2025

    Correct - that's why it specifically states them.

    EliazLBAuthor
    Graduate II
    April 8, 2025

    Alright perfect then, thank you very much !