Real Time on STM32F103RDT6

Posted on November 22, 2011 at 20:35

You'll need different RTC initialization code paths based on the type of reset (power-on, standby, etc). For example there is clearly no point starting up and waiting for the LSE if it is already running. Take a look at some of the example code, it is really worth reviewing before coding randomly. Personally I find the STANDBY model to turn things off works significantly better than just killing the supply.

void RTC_Configuration(void)

{

  /* Check if the StandBy flag is set */

  if(PWR_GetFlagStatus(PWR_FLAG_SB) != RESET)

  {/* System resumed from STANDBY mode */

    /* Turn on led connected to GPIO_LED Pin7 */

    GPIO_SetBits(GPIO_LED, GPIO_Pin_7);

    /* Clear StandBy flag */

    PWR_ClearFlag(PWR_FLAG_SB);

    /* Wait for RTC APB registers synchronisation */

    RTC_WaitForSynchro();

    /* No need to configure the RTC as the RTC configuration(clock source, enable,

       prescaler,...) is kept after wake-up from STANDBY */

  }

  else

  {/* StandBy flag is not set */

    /* RTC clock source configuration ----------------------------------------*/

    /* Reset Backup Domain */

    BKP_DeInit();

    /* Enable LSE OSC */

    RCC_LSEConfig(RCC_LSE_ON);

    /* Wait till LSE is ready */

    while(RCC_GetFlagStatus(RCC_FLAG_LSERDY) == RESET)

    {

    }

    /* Select the RTC Clock Source */

    RCC_RTCCLKConfig(RCC_RTCCLKSource_LSE);

    /* Enable the RTC Clock */

    RCC_RTCCLKCmd(ENABLE);

    /* RTC configuration -----------------------------------------------------*/

    /* Wait for RTC APB registers synchronisation */

    RTC_WaitForSynchro();

    /* Set the RTC time base to 1s */

    RTC_SetPrescaler(32767);

    /* Wait until last write operation on RTC registers has finished */

    RTC_WaitForLastTask();

  }

}

  /* Enable PWR and BKP clock */

  RCC_APB1PeriphClockCmd(RCC_APB1Periph_PWR | RCC_APB1Periph_BKP, ENABLE);

  /* Enable WKUP pin */

  PWR_WakeUpPinCmd(ENABLE);

  /* Allow access to BKP Domain */

  PWR_BackupAccessCmd(ENABLE);

  /* Configure RTC clock source and prescaler */

  RTC_Configuration();

Posted on November 25, 2011 at 11:02

Thanks your reply. i tried to do variety of ways but my issue don't solved. :(

Posted on November 25, 2011 at 15:15

i tried to do variety of ways but my issue don't solved.

You'll have to break out the debugger and oscilloscope and chase down where that 4-6 seconds is going. It's not typical, but dealing with the RTC is a complex task, with a lot of interactions with how the system is shutdown, and restarted.