STM32 Nucleo h745zi-q: USB-Device not recognized

[carlo3]

Hey im currently trying to use the CubeIDE to create a simple USB COM Communication. 
I used the following settings

System Core

• RCC: HSE = Crystal\Ceramic Resonator

 

Connectivity

• USB_OTG_FS
  • Mode: Device_Only
  • VBUS: Disable
  • No Activate_SOF
  • Speed: Fullspeed 12Mbits

 

Middleware:

• USB_DEVICE_M7: Class for FS IP = Virtual Com Port

Clock Config

 

The NVIC1 USB on the go fs global interrupt also seems to be set. 
When i run the generated code however, windows gives me the warning, that the usb-device is not recognized. 
In the device manager it says Code 43, error requesting the USD_device descriptors. 

Does anyone have an Idea, why this error is occuring? I think my clock or general setup could be the problem, but I sadly haven't found the issue yet. 
Any help is greatly appreciated

 

[carlo3]

Literally 10 Minutes after this post, i got it working. 
I changed the usb clock from PPLL3Q to RC48. 

Now the new question: Why is it working now? Configuring clocks is quiet new to me and I don't realy get the difference between the to options i tried. 
The first one (which wasn't working) also seemed to provide 48Mhz, why is the second one working but not the first. 
Sorry if this seems obvious to you, but i dont get it. 

[TDK]

> I changed the usb clock from PPLL3Q to RC48. 

USB needs a 48 MHz clock. PLL3Q is 48.011364 MHz per your screenshot, which is not 48 MHz so it doesn't work.

 

 

HSE on that board is a 8 MHz bypass signals coming from the ST-Link chip by default. Did you modify solder bridges to use the 25 MHz crystal instead?