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STM32L0 wake up pin 1 (PA0) not working?

chai2145
Associate III

Hi, 

I would like to use system wake-up pin 1 (PA0) as an external interrupt to wake up my MCU from standby mode. Understand that a rising edge on PA0 (wake-up pin 1) should trigger the MCU to exit standby mode. However, I am encountering difficulties in waking up the MCU using this pin. The pin configuration is shown in the attached picture.

chai2145_0-1732069413356.png

Circuit: Supply high voltage to VIN (5V)to wakeup MCU.

chai2145_1-1732073239975.png

 

Code: 

 

 

 

/* USER CODE BEGIN Header */
/**
  ******************************************************************************
  * @file           : main.c
  * @brief          : Main program body
  ******************************************************************************
  * @attention
  *
  * Copyright (c) 2024 STMicroelectronics.
  * All rights reserved.
  *
  * This software is licensed under terms that can be found in the LICENSE file
  * in the root directory of this software component.
  * If no LICENSE file comes with this software, it is provided AS-IS.
  *
  ******************************************************************************
  */
/* USER CODE END Header */
/* Includes ------------------------------------------------------------------*/
#include "main.h"

/* Private includes ----------------------------------------------------------*/
/* USER CODE BEGIN Includes */

/* USER CODE END Includes */

/* Private typedef -----------------------------------------------------------*/
/* USER CODE BEGIN PTD */

/* USER CODE END PTD */

/* Private define ------------------------------------------------------------*/
/* USER CODE BEGIN PD */

/* USER CODE END PD */

/* Private macro -------------------------------------------------------------*/
/* USER CODE BEGIN PM */

/* USER CODE END PM */

/* Private variables ---------------------------------------------------------*/

/* USER CODE BEGIN PV */

/* USER CODE END PV */

/* Private function prototypes -----------------------------------------------*/
void SystemClock_Config(void);
static void MX_GPIO_Init(void);
/* USER CODE BEGIN PFP */

/* USER CODE END PFP */

/* Private user code ---------------------------------------------------------*/
/* USER CODE BEGIN 0 */

/* USER CODE END 0 */

/**
  * @brief  The application entry point.
  * @retval int
  */
int main(void)
{

  /* USER CODE BEGIN 1 */

  /* USER CODE END 1 */

  /* MCU Configuration--------------------------------------------------------*/

  /* Reset of all peripherals, Initializes the Flash interface and the Systick. */
  HAL_Init();

  /* USER CODE BEGIN Init */

  /* USER CODE END Init */

  /* Configure the system clock */
  SystemClock_Config();

  /* USER CODE BEGIN SysInit */

  /* USER CODE END SysInit */

  /* Initialize all configured peripherals */
  MX_GPIO_Init();
  /* USER CODE BEGIN 2 */
  HAL_GPIO_WritePin(GPIOB, GPIO_PIN_13, GPIO_PIN_SET); //turn ON led
  /* Check and handle if the system was resumed from Standby mode */
  if (__HAL_PWR_GET_FLAG(PWR_FLAG_SB) != RESET)
  {
	/* Clear Standby flag */
	__HAL_PWR_CLEAR_FLAG(PWR_FLAG_SB);
  }

  	/* Insert 5 seconds delay */
  	HAL_Delay(5000);

  	/* The Following Wakeup sequence is highly recommended prior to each Standby mode entry
  	mainly when using more than one wakeup source this is to not miss any wakeup event.
  	- Disable all used wakeup sources,
  	- Clear all related wakeup flags,
  	- Re-enable all used wakeup sources,
  	- Enter the Standby mode.
  	*/

  	/* Disable all used wakeup sources: PWR_WAKEUP_PIN1 */
  	HAL_PWR_DisableWakeUpPin(PWR_WAKEUP_PIN1);

  	/* Clear all related wakeup flags*/
  	__HAL_PWR_CLEAR_FLAG(PWR_FLAG_WU);

  	/* Enable WakeUp Pin PWR_WAKEUP_PIN1 connected to PA.00 */
  	HAL_PWR_EnableWakeUpPin(PWR_WAKEUP_PIN1);

  	/* Enter the Standby mode */
  	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
  */
  __HAL_PWR_VOLTAGESCALING_CONFIG(PWR_REGULATOR_VOLTAGE_SCALE1);

  /** Initializes the RCC Oscillators according to the specified parameters
  * in the RCC_OscInitTypeDef structure.
  */
  RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_MSI;
  RCC_OscInitStruct.MSIState = RCC_MSI_ON;
  RCC_OscInitStruct.MSICalibrationValue = 0;
  RCC_OscInitStruct.MSIClockRange = RCC_MSIRANGE_5;
  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_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();
  }
}

/**
  * @brief GPIO Initialization Function
  * @PAram None
  * @retval None
  */
static void MX_GPIO_Init(void)
{
  GPIO_InitTypeDef GPIO_InitStruct = {0};
/* USER CODE BEGIN MX_GPIO_Init_1 */
/* USER CODE END MX_GPIO_Init_1 */

  /* GPIO Ports Clock Enable */
  __HAL_RCC_GPIOA_CLK_ENABLE();
  __HAL_RCC_GPIOB_CLK_ENABLE();

  /*Configure GPIO pin Output Level */
  HAL_GPIO_WritePin(GPIOB, GPIO_PIN_13, GPIO_PIN_RESET);

  /*Configure GPIO pin : PB13 */
  GPIO_InitStruct.Pin = GPIO_PIN_13;
  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 MX_GPIO_Init_2 */
/* USER CODE END MX_GPIO_Init_2 */
}

/* 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 */
}

 

 

 

 

13 REPLIES 13

@PGump.1 wrote:

Hi @Karl Yamashita ,

Are you saying that the compiler puts the __enable_irq() instruction behind the /* USER CODE BEGIN 2 */ line?

If not, where do you think the __enable_irq() occurs?

Kind regards
Pedro

 


So you're saying interrupts are not enabled before the while loop?

So by using a for loop before the while loop, so the while loop is never reached, then the LED that is blinking on my Nucleo board using HAL_Delay() is a hallucination? 

int main(void)
{

  /* USER CODE BEGIN 1 */

  /* USER CODE END 1 */

  /* MCU Configuration--------------------------------------------------------*/

  /* Reset of all peripherals, Initializes the Flash interface and the Systick. */
  HAL_Init();

  /* USER CODE BEGIN Init */

  /* USER CODE END Init */

  /* Configure the system clock */
  SystemClock_Config();

  /* USER CODE BEGIN SysInit */

  /* USER CODE END SysInit */

  /* Initialize all configured peripherals */
  MX_GPIO_Init();
  MX_USART2_UART_Init();
  /* USER CODE BEGIN 2 */

  for(;;)
  {
	  HAL_Delay(500);
	  HAL_GPIO_TogglePin(LD2_GPIO_Port, LD2_Pin);
  }
  /* USER CODE END 2 */

  /* Infinite loop */
  /* USER CODE BEGIN WHILE */
  while (1)
  {
    /* USER CODE END WHILE */

    /* USER CODE BEGIN 3 */
  }
  /* USER CODE END 3 */
}

 

 

Tips and Tricks with TimerCallback https://www.youtube.com/@eebykarl
If you find my solution useful, please click the Accept as Solution so others see the solution.

If your MCU is powered with VDD = 1.8V, the resistor divider generates 1.8V which is OK.

The issue is that the resistor may be too large. Try a WKUP0 wakeup action after the MCU goes to standby mode for a long time, let's say 10 minutes or even longer. If this time it works, then reduce the resistor value may be a solution.

I know that you might working on a low power application because you are using large resistor for a voltage divider to minimum the power consuming. But using large resistor means that the capacitor discharge time is longer when VIN is off. Try a Schottky parallel with 976k and cathode connected to VIN to enable the discharging of the capacitor faster after VIN goes off.


@chai2145 wrote:

Hi SofLit

The only thing I can do is reduce the values of the resistors. 


Hello,

Did you decrease the resistors values as I suggested? what was the result?

To give better visibility on the answered topics, please click on "Accept as Solution" on the reply which solved your issue or answered your question.

Hi, 

The new PCB design is currently under fabrication. I will update you once I receive it and complete the testing.