STM32L4 exit from Sleep/Low power sleep by UART RX ISR does not work

[SAkhi.951]

Hello, I'm trying to set up sleep mode and wake up from it by sending UART message to MCU.

However, MCU does not wake up.

Details:

UART baudrate - 115200

UArt set up in DMA mode, however, before going to sleep I activate RX in IT mode.

clocks setup:

void SystemClock_Config(void)
{
  RCC_OscInitTypeDef RCC_OscInitStruct = {0};
  RCC_ClkInitTypeDef RCC_ClkInitStruct = {0};
  RCC_PeriphCLKInitTypeDef PeriphClkInit = {0};
 
  /** Initializes the CPU, AHB and APB busses clocks 
  */
  RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSI|RCC_OSCILLATORTYPE_LSI
                              |RCC_OSCILLATORTYPE_MSI;
  RCC_OscInitStruct.HSIState = RCC_HSI_ON;
  RCC_OscInitStruct.HSICalibrationValue = RCC_HSICALIBRATION_DEFAULT;
  RCC_OscInitStruct.LSIState = RCC_LSI_ON;
  RCC_OscInitStruct.MSIState = RCC_MSI_ON;
  RCC_OscInitStruct.MSICalibrationValue = 0;
  RCC_OscInitStruct.MSIClockRange = RCC_MSIRANGE_8;
  RCC_OscInitStruct.PLL.PLLState = RCC_PLL_NONE;
  if (HAL_RCC_OscConfig (&RCC_OscInitStruct) != HAL_OK)
  {
    Error_Handler();
  }
  /** Initializes the CPU, AHB and APB busses clocks 
  */
  RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_HCLK|RCC_CLOCKTYPE_SYSCLK
                              |RCC_CLOCKTYPE_PCLK1|RCC_CLOCKTYPE_PCLK2;
  RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_MSI;
  RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
  RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV1;
  RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV1;
 
  if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_0) != HAL_OK)
  {
    Error_Handler();
  }
  PeriphClkInit.PeriphClockSelection = RCC_PERIPHCLK_USART1|RCC_PERIPHCLK_USART2
                              |RCC_PERIPHCLK_ADC;
  PeriphClkInit.Usart1ClockSelection = RCC_USART1CLKSOURCE_HSI;
  PeriphClkInit.Usart2ClockSelection = RCC_USART2CLKSOURCE_PCLK1;
  PeriphClkInit.AdcClockSelection = RCC_ADCCLKSOURCE_PLLSAI1;
  PeriphClkInit.PLLSAI1.PLLSAI1Source = RCC_PLLSOURCE_HSI;
  PeriphClkInit.PLLSAI1.PLLSAI1M = 1;
  PeriphClkInit.PLLSAI1.PLLSAI1N = 8;
  PeriphClkInit.PLLSAI1.PLLSAI1P = RCC_PLLP_DIV7;
  PeriphClkInit.PLLSAI1.PLLSAI1Q = RCC_PLLQ_DIV2;
  PeriphClkInit.PLLSAI1.PLLSAI1R = RCC_PLLR_DIV2;
  PeriphClkInit.PLLSAI1.PLLSAI1ClockOut = RCC_PLLSAI1_ADC1CLK;
  if (HAL_RCCEx_PeriphCLKConfig(&PeriphClkInit) != HAL_OK)
  {
    Error_Handler();
  }
  /** Configure the main internal regulator output voltage 
  */
  if (HAL_PWREx_ControlVoltageScaling(PWR_REGULATOR_VOLTAGE_SCALE1) != HAL_OK)
  {
    Error_Handler();
  }
}

sleep procedure:

/* Ensure that MSI is wake-up system clock */ 
  __HAL_RCC_WAKEUPSTOP_CLK_CONFIG(RCC_STOP_WAKEUPCLOCK_MSI);
 
  /* Enable Power Clock */
  __HAL_RCC_PWR_CLK_ENABLE();
 
  /* Enable Flash power down mode during Sleep mode     */
  /* (uncomment this line if power consumption figures  */
  /*  must be measured with Flash still on in Low Power */
  /*  Sleep mode)                                       */
   __HAL_FLASH_SLEEP_POWERDOWN_ENABLE();  
/* Reset all RCC Sleep and Stop modes register to */
  /* improve power consumption                      */
  RCC->AHB1SMENR  = 0x0;
  RCC->AHB2SMENR  = 0x0;
  RCC->AHB3SMENR  = 0x0;
  
  RCC->APB1SMENR1 = 0x0;
  RCC->APB1SMENR2 = 0x0;
  RCC->APB2SMENR  = 0x0;
  
  while (1)
  {                   
    /* USER CODE END WHILE */
 
      print_debug_msg("Enter sleep mode", DEBUG_MSG);
      
      HAL_Delay(4);
      HAL_UART_Abort(&huart1);
     /* Activate UART RX in IT mode */
      HAL_UART_Receive_IT(&huart1, (uint8_t *)uart1_rx_buf, UART_BUF_SIZE);
       /* Reduce the System clock to below 2 MHz */
       __HAL_RCC_MSI_RANGE_CONFIG(RCC_MSIRANGE_0);
      
      /* Suspend Tick increment to prevent wakeup by Systick interrupt.         */
      /* Otherwise the Systick interrupt will wake up the device within 1ms     */
      /* (HAL time base).                                                       */
      HAL_SuspendTick();
 
      HAL_PWR_EnterSLEEPMode(PWR_LOWPOWERREGULATOR_ON, PWR_SLEEPENTRY_WFI);
      
      /* ... Low-power SLEEP mode ... */
 
      /* System is Low Power Run mode when exiting Low Power Sleep mode,
         disable low power run mode and reset the clock to initialization configuration */ 
      HAL_PWREx_DisableLowPowerRunMode();
      
      SystemClock_Config();
      
      /* Resume Tick interrupt if disabled prior to Low Power Sleep mode entry */
      HAL_ResumeTick();
      
      print_debug_msg("Exit sleep mode", DEBUG_MSG);
}

When MCU goes into sleep mode I send a message over UART and expect it to wake from UART RX ISR, which was activate in UART init fct:

HAL_NVIC_SetPriority(USART1_IRQn, 0, 0);
 
  HAL_NVIC_EnableIRQ(USART1_IRQn);

Any suggestions?

[Tesla DeLorean · Accepted solution]

Enable the sleep clocks for the resources you want to function.​

[SAkhi.951]

Hei, did not get it. If you mean peripheral clock then UART1 is clocked with HSI and it is enabled in SystemClock_Config (added code snippet for Clocks init).