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July 16, 2025
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Nucleo g431kb: What does "DNF" mean ?

  • July 16, 2025
  • 2 replies
  • 667 views

good morning, I am wondering what the DNF means in my datasheet:


Capture d’écran 2025-07-16 à 08.50.49.png

does it mean there is no connection between pb3 and the LED? then i am wondering if i can use PB3 for other instances, and i am also wondering why there is this DNF instead of just not connecting PB3 and the LED
Best regards

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

    > can i still use PB3 as GPIO input from the nucleo header for another use?

    In theory yes.

    UM2397 states:

    LD2 USER
    This green LED is connected to the following STM32G4 I/O:
    • PB8, if the configuration is SB7 ON, and SB6 OFF (default configuration)
    • PB3, if the configuration is SB7 OFF, and SB6 ON

     

    But according to the schematic PB3 is also connected to T_SWO via SB4, so it is connected to the onboard ST-Link.

    So if you want to use PB3 as GPIO it will be necessary to open SB4, and you will lose SWO.

    2 replies

    Graduate II
    July 16, 2025

    DNF = "do not fit"

     

    Keep it open usually (or think about before closing)...

     

    And yes, you can use PB3 for any other purpose, since it is not connected to LD2.

    JadAuthor
    Graduate
    July 16, 2025

    so it means that the solder bridge do not fit?
    can i still use PB3 as GPIO input from the nucleo header for another use?
    thank you for the quick awnser

    Super User
    July 16, 2025

    @Jad wrote:

    so it means that the solder bridge do not fit?


    Exactly.

    It means that it is not fitted during manufacturing - but left there as an option for the user fit, if required.

    It is pretty common throughout the industry - not specific to ST or STM32

    Sometimes you will see similar terms like DNP = Do Not Place, etc ...

     

    eg, https://fedevel.com/forum/beginners/423-dnf-do-not-fit-components

     

    #DNP #DNF #NotFitted

    mfgkwAnswer
    Graduate II
    July 16, 2025

    > can i still use PB3 as GPIO input from the nucleo header for another use?

    In theory yes.

    UM2397 states:

    LD2 USER
    This green LED is connected to the following STM32G4 I/O:
    • PB8, if the configuration is SB7 ON, and SB6 OFF (default configuration)
    • PB3, if the configuration is SB7 OFF, and SB6 ON

     

    But according to the schematic PB3 is also connected to T_SWO via SB4, so it is connected to the onboard ST-Link.

    So if you want to use PB3 as GPIO it will be necessary to open SB4, and you will lose SWO.