Dear community,
I have some issues with implementing an automatic wakeup with the RTC timer on my STM32L476RG (currently on the Nucleo-Board, will be later replaced with proprietary hardware).
I generally have two wakeup sources: either the L476 is woken up by the external wake up pin 1 on PA0 (which works fine) or it is woken up on the RTC regularly. However, the RTC doesn't seem to wake up the controller, even though I (think I) implemented it as suggested in other forum entries.
I use the HAL in my code (with some sprinklers of Arduino code), below you'll find the relevant parts of it.
The timer initialization:
void rtc_init(void)
{
// Initialize RTC Only
hrtc.Instance = RTC;
hrtc.Init.HourFormat = RTC_HOURFORMAT_24;
hrtc.Init.AsynchPrediv = 127;
hrtc.Init.SynchPrediv = 255;
hrtc.Init.OutPut = RTC_OUTPUT_DISABLE;
hrtc.Init.OutPutRemap = RTC_OUTPUT_REMAP_NONE;
hrtc.Init.OutPutPolarity = RTC_OUTPUT_POLARITY_HIGH;
hrtc.Init.OutPutType = RTC_OUTPUT_TYPE_OPENDRAIN;
HAL_RTC_Init(&hrtc);
enable_wakeup_timer();
}
void enable_wakeup_timer(void)
{
HAL_RTCEx_SetWakeUpTimer_IT(&hrtc, WAKE_UP_COUNTER, RTC_WAKEUPCLOCK_RTCCLK_DIV16);
}
void disable_wakeup_timer(void)
{
HAL_RTCEx_DeactivateWakeUpTimer(&hrtc);
}
I also configure the system clock as follows, of course before initializing the RTC:
void SystemClock_config(void)
{
//RCC_OscInitTypeDef RCC_OscInitStruct = {0};
RCC_ClkInitTypeDef RCC_ClkInitStruct = {0};
RCC_PeriphCLKInitTypeDef PeriphClkInit = {0};
HAL_PWR_EnableBkUpAccess();
__HAL_RCC_LSEDRIVE_CONFIG(RCC_LSEDRIVE_LOW);
PeriphClkInit.PeriphClockSelection = RCC_PERIPHCLK_RTC|RCC_PERIPHCLK_USART1
|RCC_PERIPHCLK_USART2|RCC_PERIPHCLK_USART3
|RCC_PERIPHCLK_I2C1|RCC_PERIPHCLK_ADC;
PeriphClkInit.RTCClockSelection = RCC_RTCCLKSOURCE_LSE;
HAL_RCCEx_PeriphCLKConfig(&PeriphClkInit);
RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_HCLK|RCC_CLOCKTYPE_SYSCLK
|RCC_CLOCKTYPE_PCLK1|RCC_CLOCKTYPE_PCLK2;
RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_HSI;
RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV2;
RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV16;
RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV1;
RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV16;
HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_0);
}
I also disable the wakeup timer on start up with the above mentioned disable_wakeup_timer function. Then, I enter the standby mode with the function below, where neccessary (where I also reset the standby and wakeup flags).
void sleep_mode_enter(void)
{
delay(LED_ON_TIME);
led_off();
timer_stop();
__HAL_PWR_CLEAR_FLAG(PWR_FLAG_WU);
__HAL_PWR_CLEAR_FLAG(PWR_FLAG_SB);
enable_wakeup_timer();
HAL_PWR_EnableWakeUpPin(WAKE_UP_PIN);
HAL_PWR_EnterSTANDBYMode();
}
Any help and hints are appreciated. Thank you in advance!
