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STM32F429 DISCO LSE wont work

Question asked by tyro on Aug 22, 2014
Latest reply on Aug 24, 2014 by tyro
Hi,
I'm compiling Demonstration on STM32F429I-Discovery_FW_V1.0.1 was work fine.
Now I fixd RTC_Configuration() on rtc.c for 32.768kHz LSE driven as below:

int8_t RTC_Configuration(void)
{

  RTC_Error = 0;
  /* Enable the PWR clock */
  RCC_APB1PeriphClockCmd(RCC_APB1Periph_PWR, ENABLE);

  /* Allow access to RTC */
  PWR_BackupAccessCmd(ENABLE);

/* LSI used as RTC source clock */
/* The RTC Clock may varies due to LSI frequency dispersion. */  
  /* Enable the LSI OSC */
  RCC_LSEConfig(RCC_LSE_ON);

  /* Wait till LSI 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; /* (32KHz / 128) - 1 = 0xFF*/
  RTC_InitStructure.RTC_HourFormat = RTC_HourFormat_24;
  RTC_Init(&RTC_InitStructure);  

  return RTC_Error;
}

But It won't count up when device running.
X2 crytal is mounted 32.768kHz/6pF, C23/C24 Capacitors are 6.8pF.
and also VBAT is powerd by 3V coin cell. R53/R54 are shorted.
Is this careless oversight?

Tyro

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