No connection to PC possible

Hi all,

I have some trouble with my new Proffie (LGT core).

The saber functions work fine but I´m unable to get the board to connect to any of my computers. Tried two Win10 Desktop PCs, two Laptops (one is Win11, the other Win10),
multiple USB ports (directly into PC, no hubs) and various (15+) cables.

The board always enters a loop with the message "Unknown USB Device (Device descriptor Request Failed) appearing and disappearing until “Windows has stopped this device because it has reported problems (Code43)”

Manually forcing Bootloader via the buttons (hold boot, press reset, release boot) on the board does not change this behavour. Also not showing up as STM32BOOLOADER in device manager.

Beginning to think, that the board is broken… -.-

Any ideas? Help would be appreciated. :pray:

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Hey how are you doing?

Thanks just wondering is this the first time you plugged in a proffie board.

Fredrik has a great video on how to install and troubleshooting usb connectivity issues.

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First time, yes.

Thanks, already seen that video. Unfortunately did not help, as I can´t get it recognized at all in the device manger/devices (even with the bootloader mode via the button combo) to even mess around with zadig or arduino. Always stuck in the unknown USB Device loop mentioned above.

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Hmmm well this is hard to say

Have you tried connecting with SD removed? They may have set “Mass Storage”.

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Yes, makes no difference.

Then you’ll probably want yo reach out yo vendor, could certainly be a defective board.


I would agree with Fett263.
It sounds like this board has something wrong with the USB circuitry, and needs to be replaced.

Normally, the only real troubleshooting that can be done is to use the buttons to see if you can get it into STM32 BOOTLOADER mode. If that doesn’t work, then there is definitely something wrong somewhere, and once cables and computer issues has been ruled out, we must conclude that the board is at fault.

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Thought so. :cry:
Just wanted to make sure I´m not missing something obvious. :slightly_smiling_face:

Thanks for your help guys.

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