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Bryon08
Visitor II
April 9, 2025
Solved

Nucleo-303RE Not Starting Up

  • April 9, 2025
  • 2 replies
  • 735 views

I am using a Nuclro-303RE to develop a USB Virtual Com port, and I am running into an issue that I cannot seem to resolve.  Just to verify things, I did put some really simple code in the flash the green indicator on the Nucleo board.

  • I have it connected to a custom board that runs the USB lines out to a USB connector.
  • It is powered externally with 5V to VIN. Jumper set for E5V. The power indicator on the Nucleo is on, and the 3.3V is running.
  • I am able to run it with the debugger tool, however, it will not run with just the USB and the 5V in.
  • When I plug in to the USB on the ST-Link board, it starts to run, i.e. the green LED will blink, and the USB will enumerate for the USB virtual com port.
  • I did add an 8MHz oscillator @ X3 and associated parts.
  • I do have a pull up on the USB line.

Nucleo-F303RE-Clock.png

 

Nucleo-F303RE-USB.png

Nucleo-F303RE-VCOM.png

 

Bryon08_0-1744207627697.png

 

 

 

 

    This topic has been closed for replies.
    Best answer by Bryon08

    Hello @FBL 

    I found the problem. I happened to press the reset button on the Nucleo, and after that it started up. I did some looking around, and found a post of yours here.

    For the Nucleo-F303, I had to remove SB12, which connects NRST to the ST-Link and the target processor. After removing it, the simple application I was using to test it out started and was able to visually confirm the LED started blinking.

    Thanks for the help!

    2 replies

    F
    FBL
    Technical Moderator
    April 10, 2025

    Hello @Bryon08 

    • > I am able to run it with the debugger tool, however, it will not run with just the USB and the 5V in.

    If I understand correctly, USB Virtual COM port application is not running when powered externally, but works fine when connected to the ST-Link USB? 

    Ensure that the external 5V power supply is stable and capable of providing sufficient current. The Nucleo board should be able to run with an external power supply if the jumper settings, solder bridges are correct.

    B
    Bryon08Author
    Visitor II
    April 10, 2025

    Hello @FBL 

    Thanks for the response. Yes, that is correct, it will start up only when the USB is connected to the ST-LINK.

    I am using the 5V input, and have the jumpers set accordingly:

     

    Bryon08_1-1744297932801.png

    The 3.3V regulator started as well.

    Other than X2 and the supporting components, the board is unchanged from when it was received.

     

    Bryon08_3-1744298062093.png

     

     

    F
    FBL
    Technical Moderator
    April 10, 2025

    Hi @Bryon08 

    It may be necessary to provide additional power to the board, ideally using the Arduino connector on the bottom of the board. Would you attach your project to reproduce on my end?

    B
    Bryon08Author
    Visitor II
    April 10, 2025

    @FBL 

    Attached is the project. Just as a sanity check, I connected +5V to vin here with the application generated from the project.

     

    Bryon08_0-1744301844219.png

    Plugging in the ST-Link it will run.

    Bryon08_1-1744301977275.png

     

     

     

     

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