STLINK V3 USB issue

phil_spobu · ‎2025-07-03

Hello all,

I've been using my STLINK V3 successfully for around half a year until it suddenly stopped working from one day to the next. When connecting it to the PC (no target) the green light is on and the red light if flashing forever. It does not turn orange like described in the manual, neither switch to constant red, as it was before. Windows it not recognizing it as an USB device at all (the first two times it showed something like unknown device, but never again since).

My setup works with another STLINK V3 so I would exclude cable, USB port issues or similar.

Any idea, what the issue here is, or how to fix it?

TDK · ‎2025-07-03

If red light is flashing, it indicates the chip is trying to connect but enumeration is failing. Typically this is due to a bad cable, perhaps a power-only cable. It could also be that your PC doesn't like that device for some USB stack reason. Rebooting can sometimes fix this.

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Andrew Neil · ‎2025-07-03

FAQ: Possible communication failure between STLINK-V3 and some recent computers

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.

phil_spobu · ‎2025-07-03

I tried already several cables ans USB ports, even another PC, but the behavior is the same. As mentioned above on the same PC, same USB port, same cable my ST Links used to work and another ST link is still working perfectly. That's why I concluded, that something with the actual STLink HW must be wrong.