USB CDC Device application: PC does not recognize the USB Device (Device unknow error 43)

[Pmang.1]

Hello to all,

I am having problems with the CDC USB Device application. Does some one have a working USB example for STM32L1? .

 I am using latest version of CubeMx and STM32L1 firmware v1.9.0. The problem is that PC does not recognize the USB Device (Device unknow error 43).

I put together a very basic app, just to check if windows (W7 or W10) recognize the USB device but it fails.

I have been doing some HW and SW check and looks all fine but can't find the problem.

I would like to test a working USB example for STM32L1 or otherwise an older firware version just for testing.

Will be very grateful if I can get some help on this.

Thanks

[Imen.D]

Hello @Pmang.1​ ,

Have a look to this FAQ: USB device not recognized, it may help you.

You can refer to the CDC example in the STM32CubeL1 firmware package and get inspired from the available one:

STM32Cube_FW_L1_V1.9.0\Projects\STM32L152D-EVAL\Applications\USB_Device\

Best Regards,

Imen

[Imen.D]

Try to swith the USB_DP & USB_DM pins.

USB DP & DM pins swapped would result in this.