Cut and paste this URL to share the unmodified register and value:
https://regviz.com/r/stm32/stm32f2/STM32F215/DBG/DBGMCU_CR#0x0
Control Register
DBG_SLEEP
DBG_STOP
DBG_STANDBY
TRACE_IOEN
TRACE_MODE
https://github.com/modm-io/cmsis-svd-stm32