Question
STM32WB55: Trying to get the RTC running based on HSE_DIV32
Hi,
I have been trying to use the HSE_DIV32 clock as input for the RTC but without success.
I cannot find any example where this is done even though it's available in the datasheet and the register map.
I have been doing this after enabling the HSE clock to 32MHz:
void RTC_Init(void)
{
RTC_TimeTypeDef sTime = {0};
RTC_DateTypeDef sDate = {0};
hrtc.Instance = RTC;
hrtc.Init.HourFormat = RTC_HOURFORMAT_24;
hrtc.Init.AsynchPrediv = 124;
hrtc.Init.SynchPrediv = 7999;
hrtc.Init.OutPut = RTC_OUTPUT_DISABLE;
hrtc.Init.OutPutPolarity = RTC_OUTPUT_POLARITY_HIGH;
hrtc.Init.OutPutType = RTC_OUTPUT_TYPE_OPENDRAIN;
hrtc.Init.OutPutRemap = RTC_OUTPUT_REMAP_NONE;
if (HAL_RTC_Init(&hrtc) != HAL_OK) {
Error_Handler();
}
if (HAL_RTCEx_BKUPRead(&hrtc, RTC_BKP_DR0) != 0x32F2) {
sTime.Hours = 0x6;
sTime.Minutes = 0xa;
sTime.Seconds = 0x0;
sTime.SubSeconds = 0x0;
sTime.DayLightSaving = RTC_DAYLIGHTSAVING_NONE;
sTime.StoreOperation = RTC_STOREOPERATION_RESET;
if (HAL_RTC_SetTime(&hrtc, &sTime, RTC_FORMAT_BCD) != HAL_OK) {
Error_Handler();
}
sDate.WeekDay = RTC_WEEKDAY_MONDAY;
sDate.Month = RTC_MONTH_APRIL;
sDate.Date = 0x16;
sDate.Year = 0x18;
if (HAL_RTC_SetDate(&hrtc, &sDate, RTC_FORMAT_BCD) != HAL_OK) {
Error_Handler();
}
HAL_RTCEx_BKUPWrite(&hrtc, RTC_BKP_DR0, 0x32F2);
}
__HAL_RCC_CLEAR_RESET_FLAGS();
}and
void HAL_RTC_MspInit(RTC_HandleTypeDef* hrtc)
{
if(hrtc->Instance==RTC)
{
RCC_OscInitTypeDef RCC_OscInitStruct;
RCC_PeriphCLKInitTypeDef PeriphClkInitStruct;
/* Enables the PWR Clock and Enables access to the backup domain */
/* To change the source clock of the RTC feature (LSE, LSI), You have to:
- Enable the power clock using __HAL_RCC_PWR_CLK_ENABLE()
- Enable write access using HAL_PWR_EnableBkUpAccess() function before to
configure the RTC clock source (to be done once after reset).
- Reset the Back up Domain using __HAL_RCC_BACKUPRESET_FORCE() and
__HAL_RCC_BACKUPRESET_RELEASE().
- Configure the needed RTc clock source */
HAL_PWR_EnableBkUpAccess();
PeriphClkInitStruct.PeriphClockSelection = RCC_PERIPHCLK_RTC;
PeriphClkInitStruct.RTCClockSelection = RCC_RTCCLKSOURCE_HSE_DIV32;
if (HAL_RCCEx_PeriphCLKConfig(&PeriphClkInitStruct) != HAL_OK) {
Error_Handler();
}
__HAL_RCC_RTCAPB_CLK_ENABLE();
__HAL_RCC_RTC_ENABLE();
__HAL_RCC_RTCAPB_CLK_ENABLE();
}
}I expect the RTC to be a 1Hz clock based on HSE after that.
What I see is that the RTC counters are not changing.
The whole system runs directly on HSE so the clock is running fine.
Kind regards,