Cut and paste this URL to share the unmodified register and value:
https://regviz.com/r/Spansion/MB9BF51xS/USB0/UDCS#0x0
UDC Status Register
Configuration Detection bit
Setup Stage Detection bit
Wake-up Detection bit
Bus Reset Detection bit
SOF Detection bit
Suspend detection bit
https://github.com/cmsis-svd/cmsis-svd-data