Using Nucleo-STM32F401RE, can I connect a USB to PA9, PA10, PA11, PA12 and be able to do USB Device CDC operations?

[TDK]

The Nucleo board doesn't have a USB connector attached to those pins. But if (1) you whitewired one and (2) it meets the USB timing requirements, and (3) you use an accurate clock source, and (4) write the code to do so, sure you can get it to act as a USB CDC device.

[warm38]

"(3) you use an accurate clock source"? When I set up the project including a USB_Decice it set the clock to 48MHz and everything else to 16MHz. Hopefully that is what you are referring to. So I'm half way there once I can get in a USB connector and see how my PC likes it. Thanks for the answer.

[TDK]

USB also has accuracy requirements on the clock which can typically only be met by using a crystal as a clock source. Good luck.