R21 and R22

[wocard2]

The STM32F303xC datasheet says:

No external termination series resistors are required on USB_DP (D+) and USB_DM (D-), the matching impedance is already included in the embedded driver.

In consequence, R21 and R22 should be populated with 0 Ω resistors.

[jankae]

Ah, thanks for the info :) I probably didn't read the datasheet that closely and simply replicated what I have used in other projects for USB. There were never any issues with the 22R resistors but of course the correct solution according to the datasheet would be using 0R resistors.