MCU wakes-up from standby mode by external signal on the wake-up pin (PA0). Also, the RTC alarm does produce an interrupt when NOT in standby mode (callback function does send some characters to UART). BUT, if the MCU is in standby it cannot wake-up by the RTC alarm. Below are all relevant routines. Initialization code by CubeMX version 4.27.0. If anyone can see any problem with the code please let me know! THANKS!!!
void HAL_RTC_MspInit(RTC_HandleTypeDef* hrtc)
{
if(hrtc->Instance==RTC)
{
/* USER CODE BEGIN RTC_MspInit 0 */
/* USER CODE END RTC_MspInit 0 */
HAL_PWR_EnableBkUpAccess();
/* Enable BKP CLK enable for backup registers */
__HAL_RCC_BKP_CLK_ENABLE();
/* Peripheral clock enable */
__HAL_RCC_RTC_ENABLE();
/* RTC interrupt Init */
HAL_NVIC_SetPriority(RTC_IRQn, 0, 0);
HAL_NVIC_EnableIRQ(RTC_IRQn);
/* USER CODE BEGIN RTC_MspInit 1 */
/* USER CODE END RTC_MspInit 1 */
}
}
void RTC_IRQHandler(void)
{
/* USER CODE BEGIN RTC_IRQn 0 */
/* USER CODE END RTC_IRQn 0 */
HAL_RTC_AlarmIRQHandler(&hrtc);
/* USER CODE BEGIN RTC_IRQn 1 */
/* USER CODE END RTC_IRQn 1 */
/* RTC init function */
static void MX_RTC_Init(void)
{
/**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)
{
_Error_Handler(__FILE__, __LINE__);
}
/**Initialize RTC and set the Time and Date
*/
if(HAL_RTCEx_BKUPRead(&hrtc, RTC_BKP_DR1) != 0x32F2)
{
sTime.Hours = 0x00;
sTime.Minutes = 0x00;
sTime.Seconds = 0x00;
if (HAL_RTC_SetTime(&hrtc, &sTime, RTC_FORMAT_BCD) != HAL_OK)
{
_Error_Handler(__FILE__, __LINE__);
}
DateToUpdate.WeekDay = RTC_WEEKDAY_MONDAY;
DateToUpdate.Month = RTC_MONTH_NOVEMBER;
DateToUpdate.Date = 0x01;
DateToUpdate.Year = 0x12;
if (HAL_RTC_SetDate(&hrtc, &DateToUpdate, RTC_FORMAT_BCD) != HAL_OK)
{
_Error_Handler(__FILE__, __LINE__);
}
HAL_RTCEx_BKUPWrite(&hrtc,RTC_BKP_DR1,0x32F2);
}
}
void HAL_RTC_AlarmAEventCallback(RTC_HandleTypeDef *hrtc)
{
while (HAL_UART_Transmit(&huart1, (uint8_t*) "Hello!!\r\n", 9, UART_Timeout)==HAL_BUSY) {HAL_Delay(1);} // transmit data
}
void RTC_Alarm(void) // Alarm setup routine
{
/*################# Configure the RTC Alarm peripheral #################*/
sAlarm.Alarm = RTC_ALARM_A;
sAlarm.AlarmTime.Hours = 0x0;
sAlarm.AlarmTime.Minutes = 0x00;
sAlarm.AlarmTime.Seconds = 0x10;
HAL_RTC_SetAlarm_IT(&hrtc,&sAlarm,RTC_FORMAT_BCD);
}
void Enter_StandbyMode(void)
{
/* Enable Power Clock*/
__HAL_RCC_PWR_CLK_ENABLE();
/* Allow access to Backup */
HAL_PWR_EnableBkUpAccess();
/* Reset RTC Domain */
__HAL_RCC_BACKUPRESET_FORCE();
__HAL_RCC_BACKUPRESET_RELEASE();
/* Disable all used wake-up sources: Pin1(PA.0) */
HAL_PWR_DisableWakeUpPin(PWR_WAKEUP_PIN1);
/* Clear all related wake-up flags */
__HAL_PWR_CLEAR_FLAG(PWR_FLAG_WU);
/* Re-enable all used wake-up sources: Pin1(PA.0) */
HAL_PWR_EnableWakeUpPin(PWR_WAKEUP_PIN1);
/* Request to enter STANDBY mode */
HAL_PWR_EnterSTANDBYMode();
}
