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Explorer II
August 6, 2025
Question

ST-Link V3 Not Detected, Only a Faint Red LED - Is it Dead?

  • August 6, 2025
  • 3 replies
  • 1104 views

Hi everyone, I'm having an issue with a brand new ST-Link V3 and would appreciate a quick sanity check before I return it.

Here's the situation:

* The device is not detected by my PC at all (it does not appear in Device Manager).

* I have already confirmed my USB-C data cable is working correctly.

* The red power LED on the ST-Link is extremely faint and dim.

* I also tested it on a second computer, and the result was exactly the same.

Since the LED is so dim and it fails on multiple PCs, I'm confident this is a hardware fault (DOA). Has anyone seen this specific issue before? I've attached a photo of the dim LED.

 

Thanks for any input!

 

IMG_5514 大.jpeg

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    3 replies

    Technical Moderator
    August 6, 2025
    ST Employee
    August 6, 2025

    Hello,

    If the problem occurs from out of the box, I agree it is most probably either an hardware issue, or a wrong programming of the board; so I suggest to ask for an exchange. Before this, may you please have a look in the device manager (if you are on Windows), in "Universal Serial Bus Devices", if you see "STM32 ST-LINK/V3", or any failing device ? (in this last case, it could be helpful the check, in the device details, the USB vendorId (ST=0x0483), and USB productId)

    May you please also precise the data on the sticker of the probe (something like LKV3SET$xxx and a serial number with 1 letter and 9 digits), so that I forward to the industrialization team for analysis.

    Thank you and sorry for this trouble

    Graduate II
    August 20, 2025

    I have this problem too with STLINK-V3MODS (all 5 of them). Win10Pro 22H2 x64. Installed latest STSW-LINK009 but device does not show up in device manager. After detecting STLINK in STM32CubeProg SLINK-V3MODS starts blinkind RED. This is strange because I updated dozens of other STLINKs on the same machine and all worked fine on exactly the same port.

    I am FreeBSD user, all works fine here, OpenOCD, etc, but I cannot firmware upgrade as STM32FirmwareUpgrade.jar refuses to work. I need to enable Bridge UART with control lines in addition to JTAG/SWD+VCP functionality.

    FIX: STLINK worked fine when attached to a different port of the same computer (no 3.1 hubs on the road), it showed up in the device manager, I was able to upgrade firmware ;)

    ST Employee
    August 21, 2025

    Hello,

    this problem is different from the initial one. In your case, it looks like the V3MODS are well programmed as they work on different port (if I well understood). So your issue seems rather related to the USB renumeration required for firmware upgrade. Have you attempted the firmware upgrade on all your USB ports ? Does STM32cubeProg (or any other tool) work (in nominal case, without firmware upgrade) on the USB port where STLinkUpgrade fails ?

    I also don't understand how STM32CubeProg could detect an STLINK if it does not show in the device manager, there is perhaps a delay between both observations ?

    May you please provide more details about the STLinkUpgrade.jar failure (displayed message at the bottom if any, after which action, ...), and possibly also try STLinkUpgrade.exe as you are on Windows (just in case of (unlikely) issue with java context) ?

    Thank you

    Graduate II
    August 21, 2025

    Thanks @S C I was finally able to enumerate STLINK when using different USB port and no USB HUB on the way (I updated my FIX description above sorry if it was unclear). Only then STLINK showed in the device manager, could be detected by upgrade tool, and I was able to upgrade firmware. Looks like there are enumeration problems when USB HUB is on the way (either internal or external).

    Btw, CubeProg is -1 version behind the standalone UpgradeTool even after update to latest version.

    Regarding the standalone upgrade utility for FreeBSD here is a dedicated thread [1] but it looks like ST may not be interested in porting to FreeBSD. I can help you with that. Whole FreeBSD community could then just use this tool on our main workstation :)

    [1] https://community.st.com/t5/stm32-mcus-boards-and-hardware/stsw-link007-on-freebsd/m-p/832680