Cut and paste this URL to share the unmodified register and value:
https://regviz.com/r/stm32/stm32f7/STM32F730/USART1/RQR#0x0
Request register
Auto baud rate request
Send break request
Mute mode request
Receive data flush request
Transmit data flush request
https://github.com/modm-io/cmsis-svd-stm32