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Explorer II
June 16, 2025
Solved

STM32F407-Disc1: UART1 on PA10+PA9 does not work

  • June 16, 2025
  • 1 reply
  • 412 views

My company has purchased STM32F407G-Disc 1 board for evaluation in order to use STM32F407VE in our hardware.

UART6 (PC6 + PC7) works fine but UART 1 (PA10 + PA9) does not work.

I found in some old posts that in the discovery board there is a large capacitor connected to PA9 that prevents the uart from working.

Is this true? Does this mean that in my final hardware design there will be no such issue and UART 1 will work fine?

Thanks.

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

    Yes, I remember that much.
    The schematics are available on ST's website, check for yourself.

    By the way, this is what the user manual has to say about this topic :

    Ozone_0-1750062454009.png

    Always a recommended read.

    1 reply

    OzoneAnswer
    Explorer
    June 16, 2025

    Yes, I remember that much.
    The schematics are available on ST's website, check for yourself.

    By the way, this is what the user manual has to say about this topic :

    Ozone_0-1750062454009.png

    Always a recommended read.

    Super User
    June 16, 2025

    @chkolli also in the User Manual:

    AndrewNeil_0-1750063226448.png

    https://www.st.com/resource/en/user_manual/um1472-discovery-kit-with-stm32f407vg-mcu-stmicroelectronics.pdf#page=21

    via: https://www.st.com/en/evaluation-tools/stm32f4discovery.html#documentation

     

    The User Manual tells you that both PA9 and PA10 are occupied by USB:

    AndrewNeil_1-1750063429457.png

     


    @chkolli wrote:

    Does this mean that in my final hardware design there will be no such issue and UART 1 will work fine?


    Yes - but you then won't be able to use USB on those pins.

    Check the Datasheet to see if there are any other restrictions ...