Hello,
I'm facing some issue regarding the RTC peripheral of the STM32F103.
In particular, apperently, the RTC seems to randomly loose the configuration given:
- The RTC device is always powered, and configuration is done ideally only once (except in case of reset)
- Both the RTC Vbat and VDD comes from the same power supply rail (when in standby it comes from a tadiran lithium battery backed up with a 100mF supercap)
- I'm setting the RTC with a prescaler value of 32 to have a tick of almost 1 ms
- Sometimes on some samples it happens that the RTC is not counting at 1 ms anymore but it in fact counts every seconds
By attaching with the debugger to a running target device with this problem I found out that the prescaler value seems to be set at the default value 0f 0x8000:
The initialization code is as follow:
/**
* @brief Configures RTC clock source and prescaler.
* @param None
* @retval None
*/
void RTC_Configuration(void)
{
uint8_t retVal;
RCC_PeriphCLKInitTypeDef PeriphClkInit = {0};
RCC_OscInitTypeDef RCC_OscInitStruct = {0};
/* Initialize RTC Only */
//MyRtc = 0; //20200909 controlla
RtcHandle.Instance = RTC;
RtcHandle.Init.AsynchPrediv = 32; /* Set the RTC time base to ~1ms */
RtcHandle.Init.OutPut = RTC_OUTPUTSOURCE_NONE;
if(READ_BIT(PWR->CSR, PWR_CSR_SBF) != RESET) /* Check if the StandBy flag is set */
{
/* System resumed from STANDBY mode */
//putstring("test2\r\n");
Flag_stby = TRUE;
/* Clear StandBy flag */
//PWR_ClearFlag(PWR_FLAG_SB);
SET_BIT(PWR->CR, PWR_CR_CSBF);
/* Wait for RTC APB registers synchronisation */
//RTC_WaitForSynchro();
retVal = HAL_RTC_WaitForSynchro(&RtcHandle);
if(HAL_TIMEOUT == retVal) /*reinit*/
{
RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_LSE;
RCC_OscInitStruct.LSEState = RCC_LSE_ON;
if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)
{
Error_Handler();
}
PeriphClkInit.PeriphClockSelection = RCC_PERIPHCLK_RTC;
PeriphClkInit.RTCClockSelection = RCC_RTCCLKSOURCE_LSE; /* 32768 Hz */
if (HAL_RCCEx_PeriphCLKConfig(&PeriphClkInit) != HAL_OK)
{
Error_Handler();
}
if (HAL_RTC_Init(&RtcHandle) != HAL_OK)
{
Error_Handler();
}
}
/* 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();
//putstring("reinit\r\n");
__HAL_RCC_BACKUPRESET_FORCE();
__HAL_RCC_BACKUPRESET_RELEASE();
//putstring("tout\r\n");
MyRtc = MY_RTC_RESET_CODE; //reset error
/* Clear StandBy flag */
SET_BIT(PWR->CR, PWR_CR_CSBF);
/* Enable LSE OSC */
//RCC_LSEConfig(RCC_LSE_ON);
/* Wait till LSE is ready */
//while(RCC_GetFlagStatus(RCC_FLAG_LSERDY) == RESET)
//{
//}
RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_LSE;
RCC_OscInitStruct.LSEState = RCC_LSE_ON;
if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)
{
Error_Handler();
}
/* 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 ~1ms (1.007)*/
//RTC_SetPrescaler(32);
/* Wait until last write operation on RTC registers has finished */
//RTC_WaitForLastTask();
PeriphClkInit.PeriphClockSelection = RCC_PERIPHCLK_RTC;
PeriphClkInit.RTCClockSelection = RCC_RTCCLKSOURCE_LSE; /* 32768 Hz */
if (HAL_RCCEx_PeriphCLKConfig(&PeriphClkInit) != HAL_OK)
{
Error_Handler();
}
if (HAL_RTC_Init(&RtcHandle) != HAL_OK)
{
Error_Handler();
}
}
HAL_PWR_EnableBkUpAccess();
}May you provide some insight of this problem?
Best regards,
Matteo Cardani
