Backup Domain ResetThe backup domain reset sets all RTC registers and the RCC_BDCR register to their resetvalues. A backup domain reset is generated when one of the following events occurs:1. Software reset, triggered by setting the BDRST bit in the RCC Backup domain controlregister (RCC_BDCR). You can use the RCC_BackupResetCmd().2. VDD or VBAT power on, if both supplies have previously been powered off.