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Associate III
July 16, 2025
Solved

Nucleo g431kb: What does "DNF" mean ?

  • July 16, 2025
  • 2 replies
  • 669 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

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

Associate 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
Associate III
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

Andrew Neil
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

A complex system that works is invariably found to have evolved from a simple system that worked.A complex system designed from scratch never works and cannot be patched up to make it work.
mfgkwBest answer
Associate 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.