Is external crystal is needed for USB communication ?

[SSing.10]

Hi All,

I am working on the STM32F0 series for USB based application as Mass Storage Class and completed my initial testing on the NUCLEO-F767ZI board & POC's.

Further I have done & completed my custom hardware development, but I have didn't connect external crystal(DNP) on custom board.

Did I need to confirm that, external crystal is required in custom board developed to run the USB - Mass Storage Device ?

Looking forward for responses.

Thanks & Regards

Sachin

[Tesla DeLorean]

It is recommended to keep USB clock within specification. Without it you risk issues of connectivity related to temperature, or host system implementation. ie difference in clock offset between host and device exceed tolerances.

See if it is a check-box item for USB Certification

[TDK]

Some STM32F0 chips support crystal-less USB. Otherwise you need a crystal to adhere to timing requirements.

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

[SSing.10]

Ok I can see some STM32 MCU are having internal USB oscillator.

Please confirm and correct me if I am wrong in getting proper configurations & settings, I am currently using STM32F730V8T6 so does it require external oscillator for my usb related operations.

Please confirm me for the same.

[TDK]

The STM32F730V8T6 requires an external crystal to satisfy USB timing requirements per the datasheet.

[SSing.10]

Hi @TDK​ ,

Thanks for confirming the crystal requirement for STM32F730V8T6, I have assembled and it works.