RTC internal wake-up doesn't wake-up STM32U5

[Freiherrundbaron]

Hello,

I have my STM32U575 set to wake-up from standby-mode by the reset button of the Nucleo-U575ZI-Q. Furthermore I want the MCU to wake-up periodically triggered by the RTC. The sample code below just makes the reset button work but the RTC doesn't wake the MCU. I really can't figure out why that is the case and it seems I'm missing something obvious. Checking the relevant registers in debug mode also hasn't brought me any enlightenment.

Thanks in advance!

/* Includes ------------------------------------------------------------------*/
#include "main.h"
 
/* Private variables ---------------------------------------------------------*/
 
RTC_HandleTypeDef hrtc;
 
/* Private function prototypes -----------------------------------------------*/
void SystemClock_Config(void);
static void SystemPower_Config(void);
static void MX_GPIO_Init(void);
static void MX_RTC_Init(void);
int main(void)
{
 /* MCU Configuration--------------------------------------------------------*/
 
 /* Reset of all peripherals, Initializes the Flash interface and the Systick. */
 HAL_Init();
 
 /* Configure the system clock */
 SystemClock_Config();
 
 /* Configure the System Power */
 SystemPower_Config();
 
 /* Initialize all configured peripherals */
 MX_GPIO_Init();
 MX_RTC_Init();
 
 /* USER CODE BEGIN 2 */
 
 HAL_DBGMCU_EnableDBGStandbyMode();
 if(__HAL_PWR_GET_FLAG(PWR_FLAG_SBF)){
	 // Clear flags
	 __HAL_PWR_CLEAR_FLAG(PWR_WAKEUP_FLAG2|PWR_FLAG_SBF);
 
	 //Blink
	 HAL_GPIO_WritePin(LED_GREEN_GPIO_Port, LED_GREEN_Pin, GPIO_PIN_SET);
	 HAL_Delay(1000);
	 HAL_GPIO_WritePin(LED_GREEN_GPIO_Port, LED_GREEN_Pin, GPIO_PIN_RESET);
 }
 
 // Blink
 HAL_GPIO_WritePin(LED_BLUE_GPIO_Port, LED_BLUE_Pin, GPIO_PIN_SET);
 HAL_Delay(1000);
 
 // RTC
 HAL_RTCEx_DeactivateWakeUpTimer(&hrtc);
 __HAL_RTC_WAKEUPTIMER_CLEAR_FLAG(&hrtc, RTC_FLAG_WUTF);
 if (HAL_RTCEx_SetWakeUpTimer_IT(&hrtc, 0x1388, RTC_WAKEUPCLOCK_RTCCLK_DIV16, 0) != HAL_OK)
 {
 Error_Handler();
 }
 
 // Wake-up pin
 HAL_PWR_DisableWakeUpPin(PWR_WAKEUP_PIN2_LOW_1);
 __HAL_PWR_CLEAR_FLAG(PWR_WAKEUP_FLAG2);
 HAL_PWR_EnableWakeUpPin(PWR_WAKEUP_PIN2_LOW_1);
 
// Enter standby
 HAL_PWR_EnterSTANDBYMode();
 
 /* USER CODE END 2 */
 
 /* Infinite loop */
 /* USER CODE BEGIN WHILE */
 while (1)
 {
 /* USER CODE END WHILE */
 
 /* USER CODE BEGIN 3 */
 }
 /* USER CODE END 3 */
}
 
/**
 * @brief System Clock Configuration
 * @retval None
 */
void SystemClock_Config(void)
{
 RCC_OscInitTypeDef RCC_OscInitStruct = {0};
 RCC_ClkInitTypeDef RCC_ClkInitStruct = {0};
 
 /** Configure the main internal regulator output voltage
 */
 if (HAL_PWREx_ControlVoltageScaling(PWR_REGULATOR_VOLTAGE_SCALE4) != HAL_OK)
 {
 Error_Handler();
 }
 
 /** Initializes the CPU, AHB and APB buses clocks
 */
 RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_LSI|RCC_OSCILLATORTYPE_MSI;
 RCC_OscInitStruct.LSIState = RCC_LSI_ON;
 RCC_OscInitStruct.MSIState = RCC_MSI_ON;
 RCC_OscInitStruct.MSICalibrationValue = RCC_MSICALIBRATION_DEFAULT;
 RCC_OscInitStruct.MSIClockRange = RCC_MSIRANGE_4;
 RCC_OscInitStruct.LSIDiv = RCC_LSI_DIV1;
 RCC_OscInitStruct.PLL.PLLState = RCC_PLL_NONE;
 if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)
 {
 Error_Handler();
 }
 
 /** Initializes the CPU, AHB and APB buses clocks
 */
 RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_HCLK|RCC_CLOCKTYPE_SYSCLK
 |RCC_CLOCKTYPE_PCLK1|RCC_CLOCKTYPE_PCLK2
 |RCC_CLOCKTYPE_PCLK3;
 RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_MSI;
 RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
 RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV1;
 RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV1;
 RCC_ClkInitStruct.APB3CLKDivider = RCC_HCLK_DIV1;
 
 if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_0) != HAL_OK)
 {
 Error_Handler();
 }
}
 
/**
 * @brief Power Configuration
 * @retval None
 */
static void SystemPower_Config(void)
{
 HAL_PWREx_EnableVddIO2();
 
 /*
 * Disable the internal Pull-Up in Dead Battery pins of UCPD peripheral
 */
 HAL_PWREx_DisableUCPDDeadBattery();
 
 /*
 * Switch to SMPS regulator instead of LDO
 */
 if (HAL_PWREx_ConfigSupply(PWR_SMPS_SUPPLY) != HAL_OK)
 {
 Error_Handler();
 }
 /* PWR_S3WU_IRQn interrupt configuration */
 HAL_NVIC_SetPriority(PWR_S3WU_IRQn, 0, 0);
 HAL_NVIC_EnableIRQ(PWR_S3WU_IRQn);
}
 
/**
 * @brief RTC Initialization Function
 * @param None
 * @retval None
 */
static void MX_RTC_Init(void)
{
 
 /* USER CODE BEGIN RTC_Init 0 */
 
 /* USER CODE END RTC_Init 0 */
 
 RTC_PrivilegeStateTypeDef privilegeState = {0};
 
 /* USER CODE BEGIN RTC_Init 1 */
 
 /* USER CODE END RTC_Init 1 */
 
 /** 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;
 hrtc.Init.OutPutPullUp = RTC_OUTPUT_PULLUP_NONE;
 hrtc.Init.BinMode = RTC_BINARY_NONE;
 if (HAL_RTC_Init(&hrtc) != HAL_OK)
 {
 Error_Handler();
 }
 privilegeState.rtcPrivilegeFull = RTC_PRIVILEGE_FULL_NO;
 privilegeState.backupRegisterPrivZone = RTC_PRIVILEGE_BKUP_ZONE_NONE;
 privilegeState.backupRegisterStartZone2 = RTC_BKP_DR0;
 privilegeState.backupRegisterStartZone3 = RTC_BKP_DR0;
 if (HAL_RTCEx_PrivilegeModeSet(&hrtc, &privilegeState) != HAL_OK)
 {
 Error_Handler();
 }
 
 /** Enable the WakeUp
 */
 if (HAL_RTCEx_SetWakeUpTimer_IT(&hrtc, 0, RTC_WAKEUPCLOCK_RTCCLK_DIV16, 0) != HAL_OK)
 {
 Error_Handler();
 }
 /* USER CODE BEGIN RTC_Init 2 */
 
 /* USER CODE END RTC_Init 2 */
 
}
 
/**
 * @brief GPIO Initialization Function
 * @param None
 * @retval None
 */
static void MX_GPIO_Init(void)
{
 GPIO_InitTypeDef GPIO_InitStruct = {0};
 
 /* GPIO Ports Clock Enable */
 __HAL_RCC_GPIOC_CLK_ENABLE();
 __HAL_RCC_GPIOB_CLK_ENABLE();
 __HAL_RCC_GPIOG_CLK_ENABLE();
 __HAL_RCC_GPIOA_CLK_ENABLE();
 
 /*Configure GPIO pin Output Level */
 HAL_GPIO_WritePin(LED_RED_GPIO_Port, LED_RED_Pin, GPIO_PIN_RESET);
 
 /*Configure GPIO pin Output Level */
 HAL_GPIO_WritePin(LED_GREEN_GPIO_Port, LED_GREEN_Pin, GPIO_PIN_RESET);
 
 /*Configure GPIO pin Output Level */
 HAL_GPIO_WritePin(GPIOB, UCPD_DBn_Pin|LED_BLUE_Pin, GPIO_PIN_RESET);
 
 /*Configure GPIO pin : VBUS_SENSE_Pin */
 GPIO_InitStruct.Pin = VBUS_SENSE_Pin;
 GPIO_InitStruct.Mode = GPIO_MODE_ANALOG;
 GPIO_InitStruct.Pull = GPIO_NOPULL;
 HAL_GPIO_Init(VBUS_SENSE_GPIO_Port, &GPIO_InitStruct);
 
 /*Configure GPIO pin : UCPD_FLT_Pin */
 GPIO_InitStruct.Pin = UCPD_FLT_Pin;
 GPIO_InitStruct.Mode = GPIO_MODE_INPUT;
 GPIO_InitStruct.Pull = GPIO_NOPULL;
 HAL_GPIO_Init(UCPD_FLT_GPIO_Port, &GPIO_InitStruct);
 
 /*Configure GPIO pin : PB15 */
 GPIO_InitStruct.Pin = GPIO_PIN_15;
 GPIO_InitStruct.Mode = GPIO_MODE_ANALOG;
 GPIO_InitStruct.Pull = GPIO_NOPULL;
 HAL_GPIO_Init(GPIOB, &GPIO_InitStruct);
 
 /*Configure GPIO pin : LED_RED_Pin */
 GPIO_InitStruct.Pin = LED_RED_Pin;
 GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
 GPIO_InitStruct.Pull = GPIO_NOPULL;
 GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
 HAL_GPIO_Init(LED_RED_GPIO_Port, &GPIO_InitStruct);
 
 /*Configure GPIO pin : LED_GREEN_Pin */
 GPIO_InitStruct.Pin = LED_GREEN_Pin;
 GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
 GPIO_InitStruct.Pull = GPIO_NOPULL;
 GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
 HAL_GPIO_Init(LED_GREEN_GPIO_Port, &GPIO_InitStruct);
 
 /*Configure GPIO pins : PA9 PA10 */
 GPIO_InitStruct.Pin = GPIO_PIN_9|GPIO_PIN_10;
 GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
 GPIO_InitStruct.Pull = GPIO_NOPULL;
 GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
 GPIO_InitStruct.Alternate = GPIO_AF7_USART1;
 HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);
 
 /*Configure GPIO pins : PA11 PA12 */
 GPIO_InitStruct.Pin = GPIO_PIN_11|GPIO_PIN_12;
 GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
 GPIO_InitStruct.Pull = GPIO_NOPULL;
 GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
 GPIO_InitStruct.Alternate = GPIO_AF10_USB;
 HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);
 
 /*Configure GPIO pin : PA15 */
 GPIO_InitStruct.Pin = GPIO_PIN_15;
 GPIO_InitStruct.Mode = GPIO_MODE_ANALOG;
 GPIO_InitStruct.Pull = GPIO_NOPULL;
 HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);
 
 /*Configure GPIO pins : UCPD_DBn_Pin LED_BLUE_Pin */
 GPIO_InitStruct.Pin = UCPD_DBn_Pin|LED_BLUE_Pin;
 GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
 GPIO_InitStruct.Pull = GPIO_NOPULL;
 GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
 HAL_GPIO_Init(GPIOB, &GPIO_InitStruct);
 
}
 
/* USER CODE BEGIN 4 */
 
/* USER CODE END 4 */
 
/**
 * @brief This function is executed in case of error occurrence.
 * @retval None
 */
void Error_Handler(void)
{
 /* USER CODE BEGIN Error_Handler_Debug */
 /* User can add his own implementation to report the HAL error return state */
 __disable_irq();
 while (1)
 {
 }
 /* USER CODE END Error_Handler_Debug */
}
 
#ifdef USE_FULL_ASSERT
/**
 * @brief Reports the name of the source file and the source line number
 * where the assert_param error has occurred.
 * @param file: pointer to the source file name
 * @param line: assert_param error line source number
 * @retval None
 */
void assert_failed(uint8_t *file, uint32_t line)
{
 /* USER CODE BEGIN 6 */
 /* User can add his own implementation to report the file name and line number,
 ex: printf("Wrong parameters value: file %s on line %d\r\n", file, line) */
 /* USER CODE END 6 */
}
#endif /* USE_FULL_ASSERT */

[Piranha]

https://community.st.com/s/question/0D53W00001bnh8dSAA/how-to-enter-standby-or-shutdown-mode-on-stm32

https://community.st.com/s/question/0D53W00000NY28FSAT/clearing-the-rtc-wutf-saving-your-sanity-by-sharing-my-hard-lesson-learned-

[FBESS.1]

Did you manage to get it work ? I am facing the same problem.

[FBESS.1]

OK, after investigation I have probably found the solution to your problem (at least it worked for me).

Try to insert this line of code, before entering standby mode :

HAL_PWR_EnableWakeUpPin(PWR_WAKEUP_PIN7_HIGH_3);

I did not see any tutorial telling about that but it makes sense when you read the stm32u5xx_hal_pwr.h file or in the datasheet (Table 86. PWR wakeup source selection in RM0456).

[Freiherrundbaron]

Thank you for sharing your solution. I currently don't have a board, but I will try to test it as soon as I get one.

[fabioc]

In my case, I was missing the call to:

HAL_DBGMCU_EnableDBGStandbyMode();

By adding that, the RTC internal wake-up started to work.

Any idea as to why though? I don't think that should be enabled during sleep, because according to the Reference Manual:

"All active clocks and oscillators continue to run during Stop mode, allowing full debug capability."

so this is also increasing the power consumption during sleep.

[Piranha]

Can you see a difference in names Sleep, Stop and Standby?

Also, as can be seen from the comments, nobody of the posters did read the links I gave. Until you do that, there is no point in wondering why these features don't work...

[fabioc]

Thanks Piranha, apologies I took some shortcuts in my message.
The OP is using Sleep mode, I'm having the same problem (RTC internal wake-up doesn't wake-up STM32U5) in Stop mode. In my case what solved the issue was to add a call to HAL_DBGMCU_EnableDBGStopMode() before entering Stop mode (similarly to what the OP had in their post). Although that solves the problem, it's causing an increased current consumption during Stop mode that is not ideal.
I had read both of the link you posted (even before coming across this post) but those didn't help me.