Debug MCU APB1 freeze register1
| DBG_TIM2_STOP | TIM2 counter stopped when core is halted |
| DBG_TIM6_STOP | TIM6 counter stopped when core is halted |
| DBG_TIM7_STOP | TIM7 counter stopped when core is halted |
| DBG_RTC_STOP | RTC counter stopped when core is halted |
| DBG_WWDG_STOP | Window watchdog counter stopped when core is halted |
| DBG_IWDG_STOP | Independent watchdog counter stopped when core is halted |
| DBG_I2C1_STOP | I2C1 SMBUS timeout counter stopped when core is halted |
| DBG_I2C2_STOP | I2C2 SMBUS timeout counter stopped when core is halted |
| DBG_I2C3_STOP | I2C3 SMBUS timeout counter stopped when core is halted |
| DBG_CAN_STOP | bxCAN stopped when core is halted |
| DBG_LPTIM1_STOP | LPTIM1 counter stopped when core is halted |