Question
STMH745 and RTC issue
Hello, I'm using a stm32h745 on my new board with an external 32768Hz quart and setup RTC at startup as follow (using LSE):
HalErr_tError HalRtc_Init(void)
{
HalErr_tError zError = HalErr_eNoError;
/* Configure RTC prescaler and RTC data registers */
/* RTC configured as follows:
- Hour Format = Format 24
- Asynch Prediv = Value according to source clock
- Synch Prediv = Value according to source clock
- OutPut = Output Disable
- OutPutPolarity = High Polarity
- OutPutType = Open Drain */
gRtcHandle.Instance = RTC;
gRtcHandle.Init.HourFormat = RTC_HOURFORMAT_24;
gRtcHandle.Init.AsynchPrediv = RTC_ASYNCH_PREDIV;
gRtcHandle.Init.SynchPrediv = RTC_SYNCH_PREDIV;
gRtcHandle.Init.OutPut = RTC_OUTPUT_DISABLE;
gRtcHandle.Init.OutPutPolarity = RTC_OUTPUT_POLARITY_HIGH;
gRtcHandle.Init.OutPutType = RTC_OUTPUT_TYPE_OPENDRAIN;
if (HAL_RTC_Init(&gRtcHandle) != HAL_OK)
{
/* Initialization Error */
zError = HalErr_eInternal;
}
/** Enable the reference Clock input */
if (HAL_RTCEx_SetRefClock(&gRtcHandle) != HAL_OK)
{
zError = HalErr_eInternal;
}
return zError;
}
void HAL_RTC_MspInit(RTC_HandleTypeDef *hrtc)
{
RCC_OscInitTypeDef RCC_OscInitStruct;
RCC_PeriphCLKInitTypeDef PeriphClkInitStruct;
/*##-1- Enables access to the backup domain ######*/
/* To enable access on RTC registers */
HAL_PWR_EnableBkUpAccess();
/*##-2- Configure LSE/LSI as RTC clock source ###############################*/
#ifdef RTC_CLOCK_SOURCE_LSE
RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_LSI | RCC_OSCILLATORTYPE_LSE;
RCC_OscInitStruct.PLL.PLLState = RCC_PLL_NONE;
RCC_OscInitStruct.LSEState = RCC_LSE_ON;
RCC_OscInitStruct.LSIState = RCC_LSI_OFF;
if(HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)
{
while(1){};
}
PeriphClkInitStruct.PeriphClockSelection = RCC_PERIPHCLK_RTC;
PeriphClkInitStruct.RTCClockSelection = RCC_RTCCLKSOURCE_LSE;
if(HAL_RCCEx_PeriphCLKConfig(&PeriphClkInitStruct) != HAL_OK)
{
while(1){};
}
/* Configures the External Low Speed oscillator (LSE) drive capability */
__HAL_RCC_LSEDRIVE_CONFIG(RCC_LSEDRIVE_HIGH);
#elif defined (RTC_CLOCK_SOURCE_LSI)
RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_LSI | RCC_OSCILLATORTYPE_LSE;
RCC_OscInitStruct.PLL.PLLState = RCC_PLL_NONE;
RCC_OscInitStruct.LSIState = RCC_LSI_ON;
RCC_OscInitStruct.LSEState = RCC_LSE_OFF;
if(HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)
{
while(1){};
}
PeriphClkInitStruct.PeriphClockSelection = RCC_PERIPHCLK_RTC;
PeriphClkInitStruct.RTCClockSelection = RCC_RTCCLKSOURCE_LSI;
if(HAL_RCCEx_PeriphCLKConfig(&PeriphClkInitStruct) != HAL_OK)
{
while(1){};
}
#else
#error Please select the RTC Clock source inside the main.h file
#endif /*RTC_CLOCK_SOURCE_LSE*/
/*##-3- Enable RTC peripheral Clocks #######################################*/
/* Enable RTC Clock */
__HAL_RCC_RTC_ENABLE();
/*##-4- Configure the NVIC for RTC Alarm ###################################*/
// HAL_NVIC_SetPriority(RTC_Alarm_IRQn, 0x0F, 0);
// HAL_NVIC_EnableIRQ(RTC_Alarm_IRQn);
UNUSED(hrtc);
}I’m experiencing some problems:
1) the clock is always slower (about 10%), no matter of the capacitor installed (even without the capacitors)
2) there is a jitter on the oscillator signal even if the RTC is powered by the Vbat and the uC is not powered
Thanks in advance for any suggestion.
Regards
