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DavidL_
Associate III
September 23, 2024
Solved

Program not running when powering from external source

  • September 23, 2024
  • 18 replies
  • 4002 views

I have an L432KC and to test it, I created a simple blinking program which I uploaded via USB, which works just fine. When connecting my MCU to my external 5V power supply though, my program does not run. Looking at some posts, I found people suggesting to pull down the Boot0 pin to ensure that it loads the user program, I am not able to find the Pin name on the board of the Boot0 pin of the L432KC though.

I'd appreciate it if someone could help me out.
Thanks in advance!

This topic has been closed for replies.
Best answer by Andrew Neil
@DavidL_ wrote:

How would I „break“ this link? What exactly does that mean?

It's here:

AndrewNeil_0-1727192204016.png

 

The photo in the UM shows a zero-ohm resistor fitted:

AndrewNeil_1-1727192253286.png

To break the link, you need to remove that zero-ohm link.

There's no need to be particularly careful with it - you don't need to keep it - so just heat it up with a soldering iron until it comes off.

 

@mƎALLEm @STTwo-32 I've noted before that this needs to be better documented:

https://community.st.com/t5/stm32-mcus-products/docmentation-of-solder-bridges/m-p/689362

 

#BreakSolderBridge #SolderBridge #SB

18 replies

TDK
TDK
September 23, 2024

You're connecting 5V to CN4 pin 4 and GND to GND somewhere?

Are you relying on the clock from the ST-Link chip? Use HSI instead.

Unlikely BOOT0 is the issue here as it is pulled down by default, unless you've modified solder bridges.

"If you feel a post has answered your question, please click ""Accept as Solution""."
    Andrew Neil
    Andrew Neil
    Super User
    September 24, 2024

    @DavidL_  You haven't said what board you're using!

     

    @TDK wrote:

    Are you relying on the clock from the ST-Link chip? Use HSI instead.

    Also, if the on-board ST-Link is not powered, it's likely to pull the Target's NRST pin down - which will hold the target in Reset ...

    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.
      Andrew Neil
      Andrew NeilBest answer
      Super User
      September 24, 2024
      @DavidL_ wrote:

      How would I „break“ this link? What exactly does that mean?

      It's here:

      AndrewNeil_0-1727192204016.png

       

      The photo in the UM shows a zero-ohm resistor fitted:

      AndrewNeil_1-1727192253286.png

      To break the link, you need to remove that zero-ohm link.

      There's no need to be particularly careful with it - you don't need to keep it - so just heat it up with a soldering iron until it comes off.

       

      @mƎALLEm @STTwo-32 I've noted before that this needs to be better documented:

      https://community.st.com/t5/stm32-mcus-products/docmentation-of-solder-bridges/m-p/689362

       

      #BreakSolderBridge #SolderBridge #SB

      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.
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