build HID keyboard by STM32F072C8T6 without external oscillators?

Posted on October 24, 2015 at 16:08

I am building HID keyboard by STM32F072C8T6, 

can I just build without external 8M&32.768K oscillators to save the layout space? any technical risk?

I don't know if the Clock Recovery System (CRS) circuitry, which could

use the USB SOF signal, is good enough for HID keyboard application?

thanks! 

BR-fino