Dear friends, I have a problem when reading counter register of RTC in STM32F103RB. After resetting the MCU, the value starts from zero. I have a 3V backup battery connected to VBAT pin. My code to config RTC is in below
void RTC_Config(void) { /* Enable PWR and BKP clocks */ RCC_APB1PeriphClockCmd(RCC_APB1Periph_PWR | RCC_APB1Periph_BKP, ENABLE); /* Allow access to BKP Domain */ PWR_BackupAccessCmd(ENABLE); /* Reset Backup Domain */ BKP_DeInit(); /* Enable LSE */ RCC_LSEConfig(RCC_LSE_ON); /* Wait till LSE is ready */ while (RCC_GetFlagStatus(RCC_FLAG_LSERDY) == RESET) {} /* Select LSE as RTC Clock Source */ RCC_RTCCLKConfig(RCC_RTCCLKSource_LSE); /* Enable RTC Clock */ RCC_RTCCLKCmd(ENABLE); /* Wait for RTC registers synchronization */ RTC_WaitForSynchro(); /* Wait until last write operation on RTC registers has finished */ RTC_WaitForLastTask(); /* Enable the RTC Second */ RTC_ITConfig(RTC_IT_SEC, ENABLE); /* Wait until last write operation on RTC registers has finished */ RTC_WaitForLastTask(); /* Set RTC prescaler: set RTC period to 1sec */ RTC_SetPrescaler(32767); /* RTC period = RTCCLK/RTC_PR = (32.768 KHz)/(32767+1) */ /* Wait until last write operation on RTC registers has finished */ RTC_WaitForLastTask(); //---------------------------------------------------- }
in main function:
rtc_val=RTC_GetCounter();