RTC initialization

Posted on January 10, 2012 at 12:13

Use code like this:

int main (void)

{

 SystemInit(); 

/* Enable the PWR clock */

  RCC_APB1PeriphClockCmd(RCC_APB1Periph_PWR, ENABLE);

  /* Allow access to RTC */

  PWR_BackupAccessCmd(ENABLE);

/***Configures the External Low Speed oscillator (LSE)****/

 

  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);

  /* Wait for RTC APB registers synchronisation */

  RTC_WaitForSynchro();

  /* Calendar Configuration with LSI supposed at 32KHz */

  RTC_InitStructure.RTC_AsynchPrediv = 0x7F;

  RTC_InitStructure.RTC_SynchPrediv =  0xFF; 

  RTC_InitStructure.RTC_HourFormat = RTC_HourFormat_24;

  RTC_Init(&RTC_InitStructure);

  .......

       while(1)

       {

        .....  //Read RTC Time Register

        ......

       }

           …

}

__task void _HORLOGE_Initialiser (void)

{

while (1)

 {          

 

     os_tsk_delete_self ();

    } ;

}

Posted on August 21, 2012 at 15:01

PWR/BKP domain needs to be clocked, and unlocked.

32KHz crystal needs to be 6pF or less.

Verify clock is running.

Show code.

Posted on August 21, 2012 at 16:03

I'm using a 6pF cristal with 12pF external capacitors.

LSE clock is running, I've checked it on MCO1 output and it's stable.

Here is code:

(I'm using stm32f2xx_stdperiph_lib)

int main(void)

{

SystemInit();

rcc_init();

RTC_init();

IO_init();

while(1){

}

}

static void rcc_init(void)

{

RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA | RCC_AHB1Periph_GPIOB | RCC_AHB1Periph_GPIOC | RCC_AHB1Periph_GPIOD |

RCC_AHB1Periph_GPIOE | RCC_AHB1Periph_DMA1 | RCC_AHB1Periph_DMA2 | RCC_AHB1Periph_BKPSRAM,ENABLE);

RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART1 | RCC_APB2Periph_SPI1 | RCC_APB2Periph_TIM1 | RCC_APB2Periph_SYSCFG,ENABLE);

RCC_APB1PeriphClockCmd(RCC_APB1Periph_USART2 | RCC_APB1Periph_USART3 | RCC_APB1Periph_TIM2 | RCC_APB1Periph_TIM3 |

RCC_APB1Periph_TIM4 | RCC_APB1Periph_TIM5 | RCC_APB1Periph_SPI3 | RCC_APB1Periph_PWR , ENABLE);

}

void RTC_init(void){

# Reset power domain

PWR_DeInit();

# Allow access to RTC

PWR_BackupAccessCmd(ENABLE);

# Write protection DISABLE

RTC_WriteProtectionCmd(DISABLE);

# Enable LSE clock

RCC_LSEConfig(RCC_LSE_ON);

# Wait till LSE is ready

while (RCC_GetFlagStatus(RCC_FLAG_LSERDY) == RESET);

# COnfig MCO1 output

RCC_MCO1Config(RCC_MCO1Source_LSE,RCC_MCO1Div_1);

# Select LSE as RTC Clock Source

RCC_RTCCLKConfig(RCC_RTCCLKSource_LSE);

# Enable RTC Clock

RCC_RTCCLKCmd(ENABLE);

# Wait for RTC registers synchronization

uint8_t odp = RTC_WaitForSynchro();

if(odp != 0){

#synchro OK

LED1_ON();LED2_OFF();

}else{

#synchro ERROR

LED2_ON();LED1_OFF();

}

}

Maybe i'm missing some thing obvious.

Posted on September 16, 2014 at 12:10

We had this problem with our system too.

If we couldn't get synchronization (INITF set true), then we issued

RCC_BackupResetCmd(

ENABLE

);

followed by

RCC_BackupResetCmd(DIS

ABLE

);

which made it work next time we tried.  We think it was caused by our battery backup voltage dropping too low.

Posted on October 14, 2014 at 15:35

I had a similar problem.

I found that I had to increase the timeout (SYNCHRO_TIMEOUT) for the RTC_WaitForSynchro() function from 0x008000 to 0x0F0000.  I tried 0x010000 & 0x040000, but they did not consistently solve the problem, though 0x040000 was better.

Vance

Posted on November 27, 2014 at 12:02

I has the same problem with RTC_ISR_INITF flag. 

I found error in usb_bsp.c file.

  /* enable the PWR clock */

  RCC_APB1PeriphResetCmd(RCC_APB1Periph_PWR, ENABLE); 

  ----->>>

  RCC_APB1PeriphClockCmd(RCC_APB1Periph_PWR, ENABLE);