stm32f3 USB D+ pull up resistor

[CGaud.1]

I've designed a board with a stm32F302C8T6 but the MCU dosent show up on windows. I didn't have a pull up resistor on D+. Could it cause that problem or the pull up isint mandaatory?

[TDK]

An external pullup is required on the STM32F3 series. It is mandatory per the USB specification. See:

https://www.st.com/resource/en/application_note/dm00296349-usb-hardware-and-pcb-guidelines-using-stm32-mcus-stmicroelectronics.pdf