Hello,
I use STM32F100RBT. I want to enter STANDBY mode and exit every second.
It works well, except for one issue: it always wakes up 1 second later.
I run the following code, where I get the current time, print it and set an alarm for the next second (this is only a test, I start from 0 seconds and check what happens in the next several prints), then I enter STANDBY.
The RTC given seconds are always incremented by 2 instead of one, as does the timestamp in the serial monitor (the RTC second progression corresponds to real time).
I tried it with other delays, like 2, 3, 4, and 5, and the RTC is always 1 second late.
Why does RTC wake the system 1 second late?
How can this be fixed?
Thanks!
void test_code()
{
RTC_DateTypeDef sdatestructure = {0};
RTC_TimeTypeDef stimestructure = {0};
hrtc.Instance = RTC;
HAL_RTC_GetTime(&hrtc, &stimestructure, RTC_FORMAT_BCD);
HAL_RTC_GetDate(&hrtc, &sdatestructure, RTC_FORMAT_BCD);
printf("wake up time: %u\n", stimestructure.Seconds);
__HAL_PWR_CLEAR_FLAG(PWR_FLAG_WU);
if(__HAL_PWR_GET_FLAG(PWR_FLAG_SB) != RESET)
{
printf("wake\n");
/* Clear Standby flag */
__HAL_PWR_CLEAR_FLAG(PWR_FLAG_SB);
}
else
{
printf("reset\n");
MX_RTC_Init();
}
RTC_AlarmTypeDef salarmstructure = {{0}, 0};
HAL_RTC_GetTime(&hrtc, &stimestructure, RTC_FORMAT_BCD);
stimestructure.Seconds += 1;
salarmstructure.Alarm = RTC_ALARM_A;
salarmstructure.AlarmTime.Hours = stimestructure.Hours;
salarmstructure.AlarmTime.Minutes = stimestructure.Minutes;
salarmstructure.AlarmTime.Seconds = stimestructure.Seconds;
if(HAL_RTC_SetAlarm_IT(&hrtc,&salarmstructure,RTC_FORMAT_BCD) != HAL_OK)
{
/* Initialization Error */
SET_CRITCAL_ERROR()
}
HAL_PWR_EnterSTANDBYMode();
}
static void MX_RTC_Init(void)
{
/* USER CODE BEGIN RTC_Init 0 */
/* USER CODE END RTC_Init 0 */
RTC_TimeTypeDef sTime = {0};
RTC_DateTypeDef DateToUpdate = {0};
/* USER CODE BEGIN RTC_Init 1 */
/* USER CODE END RTC_Init 1 */
/** Initialize RTC Only
*/
hrtc.Instance = RTC;
hrtc.Init.AsynchPrediv = RTC_AUTO_1_SECOND;
hrtc.Init.OutPut = RTC_OUTPUTSOURCE_ALARM;
if (HAL_RTC_Init(&hrtc) != HAL_OK)
{
SET_CRITCAL_ERROR()
}
sTime.Hours = 0x0;
sTime.Minutes = 0x0;
sTime.Seconds = 0x0;
if (HAL_RTC_SetTime(&hrtc, &sTime, RTC_FORMAT_BCD) != HAL_OK)
{
SET_CRITCAL_ERROR()
}
DateToUpdate.WeekDay = RTC_WEEKDAY_MONDAY;
DateToUpdate.Month = RTC_MONTH_JANUARY;
DateToUpdate.Date = 0x1;
DateToUpdate.Year = 0x0;
if (HAL_RTC_SetDate(&hrtc, &DateToUpdate, RTC_FORMAT_BCD) != HAL_OK)
{
SET_CRITCAL_ERROR()
}
}
int main(void)
{
HAL_Init();
SystemClock_Config();
MX_GPIO_Init();
MX_USART1_UART_Init();
MX_USART2_UART_Init();
test_code();
}
