FreeRTOS篇12：任务通知

最新推荐文章于 2025-04-25 20:16:44 发布

努力学习de小王

最新推荐文章于 2025-04-25 20:16:44 发布

阅读量1k

点赞数 11

文章标签： java 前端服务器

本文链接：https://blog.youkuaiyun.com/2401_83811921/article/details/142690672

版权

一.什么是任务通知？

FreeRTOS 从版本 V8.2.0 开始提供任务通知这个功能，每个任务都有一个 32 位的通知值。按照FreeRTOS 官方的说法，使用消息通知比通过二进制信号量方式解除阻塞任务快 45%，并且更加省内存（无需创建队列）。

在大多数情况下，任务通知可以替代二值信号量、计数信号量、事件标志组，可以替代长度为 1的队列（可以保存一个 32 位整数或指针值），并且任务通知速度更快、使用的RAM更少！

二.任务通知值的更新方式

FreeRTOS 提供以下几种方式发送通知给任务：

发送消息给任务，如果有通知未读，不覆盖通知值
发送消息给任务，直接覆盖通知值
发送消息给任务，设置通知值的一个或者多个位
发送消息给任务，递增通知值

通过对以上方式的合理使用，可以在一定场合下替代原本的队列、信号量、事件标志组等。

三.任务通知的优势和劣势

1.任务通知的优势

使用任务通知向任务发送事件或数据，比使用队列、事件标志组或信号量快得多。
使用其他方法时都要先创建对应的结构体，使用任务通知时无需额外创建结构体。

2.任务通知的劣势

只有任务可以等待通知，中断服务函数中不可以，因为中断没有 TCB 。
通知只能一对一，因为通知必须指定任务。
等待通知的任务可以被阻塞，但是发送消息的任务，任何情况下都不会被阻塞等待。
任务通知是通过更新任务通知值来发送数据的，任务结构体中只有一个任务通知值，只能保持一个数据。

四.任务通知相关 API 函数

1. 发送通知

参数：

xTaskToNotify：需要接收通知的任务句柄；

ulValue：用于更新接收任务通知值，具体如何更新由形参 eAction 决定；

eAction：一个枚举，代表如何使用任务通知的值；

返回值：

如果被通知任务还没取走上一个通知，又接收了一个通知，则这次通知值未能更新并返回

pdFALSE，而其他情况均返回pdPASS。

参数：

xTaskToNotify：需要接收通知的任务句柄； ulValue：用于更新接收任务通知值，具体如何更新由形参 eAction 决定； eAction：一个枚举，代表如何使用任务通知的值；

pulPreviousNotifyValue：对象任务的上一个任务通知值，如果为 NULL，则不需要回传，这个时候就等价于函数 xTaskNotify()。

返回值：

如果被通知任务还没取走上一个通知，又接收了一个通知，则这次通知值未能更新并返回

pdFALSE，而其他情况均返回pdPASS。

参数：

xTaskToNotify：接收通知的任务句柄，并让其自身的任务通知值加 1。

返回值：

总是返回 pdPASS。

2. 等待通知

等待通知API函数只能用在任务，不可应用于中断中！

参数：

xClearCountOnExit：指定在成功接收通知后，将通知值清零或减 1，pdTRUE：把通知值清零（二值信号量）；pdFALSE：把通知值减一（计数型信号量）； xTicksToWait：阻塞等待任务通知值的最大时间；

返回值：

0：接收失败非0：接收成功，返回任务通知的通知值

ulBitsToClearOnEntry：函数执行前清零任务通知值那些位。 ulBitsToClearOnExit：表示在函数退出前，清零任务通知值那些位，在清 0 前，接收到的任务通知值会先被保存到形参*pulNotificationValue 中。 pulNotificationValue：用于保存接收到的任务通知值。如果不需要使用，则设置为 NULL 即可。 xTicksToWait：等待消息通知的最大等待时间。

五.实操

1.需求

1）模拟二值信号量

2）模拟计数型信号量

3）模拟事件标志组

4）模拟邮箱

2.CubeMX配置

1）模拟二值信号量配置

3.代码实现

1）模拟二值信号量代码

/* USER CODE BEGIN Header */
/**
  ******************************************************************************
  * File Name          : freertos.c
  * Description        : Code for freertos applications
  ******************************************************************************
  * @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 "FreeRTOS.h"
#include "task.h"
#include "main.h"
#include "cmsis_os.h"

/* Private includes ----------------------------------------------------------*/
/* USER CODE BEGIN Includes */
#include <stdio.h>
/* 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 Variables */

/* USER CODE END Variables */
osThreadId TaskSendHandle;
osThreadId TaskReceiveHandle;

/* Private function prototypes -----------------------------------------------*/
/* USER CODE BEGIN FunctionPrototypes */

/* USER CODE END FunctionPrototypes */

void StartTaskSend(void const * argument);
void StartTaskReceive(void const * argument);

void MX_FREERTOS_Init(void); /* (MISRA C 2004 rule 8.1) */

/* GetIdleTaskMemory prototype (linked to static allocation support) */
void vApplicationGetIdleTaskMemory( StaticTask_t **ppxIdleTaskTCBBuffer, StackType_t **ppxIdleTaskStackBuffer, uint32_t *pulIdleTaskStackSize );

/* USER CODE BEGIN GET_IDLE_TASK_MEMORY */
static StaticTask_t xIdleTaskTCBBuffer;
static StackType_t xIdleStack[configMINIMAL_STACK_SIZE];

void vApplicationGetIdleTaskMemory( StaticTask_t **ppxIdleTaskTCBBuffer, StackType_t **ppxIdleTaskStackBuffer, uint32_t *pulIdleTaskStackSize )
{
  *ppxIdleTaskTCBBuffer = &xIdleTaskTCBBuffer;
  *ppxIdleTaskStackBuffer = &xIdleStack[0];
  *pulIdleTaskStackSize = configMINIMAL_STACK_SIZE;
  /* place for user code */
}
/* USER CODE END GET_IDLE_TASK_MEMORY */

/**
  * @brief  FreeRTOS initialization
  * @param  None
  * @retval None
  */
void MX_FREERTOS_Init(void) {
  /* USER CODE BEGIN Init */

  /* USER CODE END Init */

  /* USER CODE BEGIN RTOS_MUTEX */
  /* add mutexes, ... */
  /* USER CODE END RTOS_MUTEX */

  /* USER CODE BEGIN RTOS_SEMAPHORES */
  /* add semaphores, ... */
  /* USER CODE END RTOS_SEMAPHORES */

  /* USER CODE BEGIN RTOS_TIMERS */
  /* start timers, add new ones, ... */
  /* USER CODE END RTOS_TIMERS */

  /* USER CODE BEGIN RTOS_QUEUES */
  /* add queues, ... */
  /* USER CODE END RTOS_QUEUES */

  /* Create the thread(s) */
  /* definition and creation of TaskSend */
  osThreadDef(TaskSend, StartTaskSend, osPriorityNormal, 0, 128);
  TaskSendHandle = osThreadCreate(osThread(TaskSend), NULL);

  /* definition and creation of TaskReceive */
  osThreadDef(TaskReceive, StartTaskReceive, osPriorityNormal, 0, 128);
  TaskReceiveHandle = osThreadCreate(osThread(TaskReceive), NULL);

  /* USER CODE BEGIN RTOS_THREADS */
  /* add threads, ... */
  /* USER CODE END RTOS_THREADS */

}

/* USER CODE BEGIN Header_StartTaskSend */
/**
  * @brief  Function implementing the TaskSend thread.
  * @param  argument: Not used
  * @retval None
  */
/* USER CODE END Header_StartTaskSend */
void StartTaskSend(void const * argument)
{
  /* USER CODE BEGIN StartTaskSend */
  /* Infinite loop */
  for(;;)
  {
		if(HAL_GPIO_ReadPin(GPIOA,GPIO_PIN_0)==GPIO_PIN_RESET)
		{
		osDelay(20);
			if(HAL_GPIO_ReadPin(GPIOA,GPIO_PIN_0)==GPIO_PIN_RESET)
			{
			xTaskNotifyGive(TaskReceiveHandle);
				printf("任务通知：模拟二值信号量发送成功\r\n");
			}
			while(HAL_GPIO_ReadPin(GPIOA,GPIO_PIN_0)==GPIO_PIN_RESET);
		}
    osDelay(10);
  }
  /* USER CODE END StartTaskSend */
}

/* USER CODE BEGIN Header_StartTaskReceive */
/**
* @brief Function implementing the TaskReceive thread.
* @param argument: Not used
* @retval None
*/
/* USER CODE END Header_StartTaskReceive */
void StartTaskReceive(void const * argument)
{
  /* USER CODE BEGIN StartTaskReceive */
	uint32_t rev=0;
  /* Infinite loop */
  for(;;)
  {
		if(HAL_GPIO_ReadPin(GPIOA,GPIO_PIN_1)==GPIO_PIN_RESET)
		{
		osDelay(20);
			if(HAL_GPIO_ReadPin(GPIOA,GPIO_PIN_1)==GPIO_PIN_RESET)
			{
			rev=ulTaskNotifyTake(pdTRUE,portMAX_DELAY);
				if(rev!=0)
				printf("任务通知：模拟二值信号量接收成功\r\n");
			}
			while(HAL_GPIO_ReadPin(GPIOA,GPIO_PIN_1)==GPIO_PIN_RESET);
		}
    osDelay(1);
  }
  /* USER CODE END StartTaskReceive */
}

/* Private application code --------------------------------------------------*/
/* USER CODE BEGIN Application */

/* USER CODE END Application */

2）修改这个

3）模拟事件标志组代码

/* USER CODE BEGIN Header */
/**
  ******************************************************************************
  * File Name          : freertos.c
  * Description        : Code for freertos applications
  ******************************************************************************
  * @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 "FreeRTOS.h"
#include "task.h"
#include "main.h"
#include "cmsis_os.h"

/* Private includes ----------------------------------------------------------*/
/* USER CODE BEGIN Includes */
#include <stdio.h>
/* 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 Variables */

/* USER CODE END Variables */
osThreadId TaskSendHandle;
osThreadId TaskReceiveHandle;

/* Private function prototypes -----------------------------------------------*/
/* USER CODE BEGIN FunctionPrototypes */

/* USER CODE END FunctionPrototypes */

void StartTaskSend(void const * argument);
void StartTaskReceive(void const * argument);

void MX_FREERTOS_Init(void); /* (MISRA C 2004 rule 8.1) */

/* GetIdleTaskMemory prototype (linked to static allocation support) */
void vApplicationGetIdleTaskMemory( StaticTask_t **ppxIdleTaskTCBBuffer, StackType_t **ppxIdleTaskStackBuffer, uint32_t *pulIdleTaskStackSize );

/* USER CODE BEGIN GET_IDLE_TASK_MEMORY */
static StaticTask_t xIdleTaskTCBBuffer;
static StackType_t xIdleStack[configMINIMAL_STACK_SIZE];

void vApplicationGetIdleTaskMemory( StaticTask_t **ppxIdleTaskTCBBuffer, StackType_t **ppxIdleTaskStackBuffer, uint32_t *pulIdleTaskStackSize )
{
  *ppxIdleTaskTCBBuffer = &xIdleTaskTCBBuffer;
  *ppxIdleTaskStackBuffer = &xIdleStack[0];
  *pulIdleTaskStackSize = configMINIMAL_STACK_SIZE;
  /* place for user code */
}
/* USER CODE END GET_IDLE_TASK_MEMORY */

/**
  * @brief  FreeRTOS initialization
  * @param  None
  * @retval None
  */
void MX_FREERTOS_Init(void) {
  /* USER CODE BEGIN Init */

  /* USER CODE END Init */

  /* USER CODE BEGIN RTOS_MUTEX */
  /* add mutexes, ... */
  /* USER CODE END RTOS_MUTEX */

  /* USER CODE BEGIN RTOS_SEMAPHORES */
  /* add semaphores, ... */
  /* USER CODE END RTOS_SEMAPHORES */

  /* USER CODE BEGIN RTOS_TIMERS */
  /* start timers, add new ones, ... */
  /* USER CODE END RTOS_TIMERS */

  /* USER CODE BEGIN RTOS_QUEUES */
  /* add queues, ... */
  /* USER CODE END RTOS_QUEUES */

  /* Create the thread(s) */
  /* definition and creation of TaskSend */
  osThreadDef(TaskSend, StartTaskSend, osPriorityNormal, 0, 128);
  TaskSendHandle = osThreadCreate(osThread(TaskSend), NULL);

  /* definition and creation of TaskReceive */
  osThreadDef(TaskReceive, StartTaskReceive, osPriorityNormal, 0, 128);
  TaskReceiveHandle = osThreadCreate(osThread(TaskReceive), NULL);

  /* USER CODE BEGIN RTOS_THREADS */
  /* add threads, ... */
  /* USER CODE END RTOS_THREADS */

}

/* USER CODE BEGIN Header_StartTaskSend */
/**
  * @brief  Function implementing the TaskSend thread.
  * @param  argument: Not used
  * @retval None
  */
/* USER CODE END Header_StartTaskSend */
void StartTaskSend(void const * argument)
{
  /* USER CODE BEGIN StartTaskSend */
  /* Infinite loop */
  for(;;)
  {
		if(HAL_GPIO_ReadPin(GPIOA,GPIO_PIN_0)==GPIO_PIN_RESET)
		{
		osDelay(20);
			if(HAL_GPIO_ReadPin(GPIOA,GPIO_PIN_0)==GPIO_PIN_RESET)
			{
      printf("将bit0位置1\r\n");
				xTaskNotify(TaskReceiveHandle,0x01,eSetBits);
			}
			while(HAL_GPIO_ReadPin(GPIOA,GPIO_PIN_0)==GPIO_PIN_RESET);
		}
		
			if(HAL_GPIO_ReadPin(GPIOA,GPIO_PIN_1)==GPIO_PIN_RESET)
		{
		osDelay(20);
			if(HAL_GPIO_ReadPin(GPIOA,GPIO_PIN_1)==GPIO_PIN_RESET)
			{
      printf("将bit1位置1\r\n");
				xTaskNotify(TaskReceiveHandle,0x02,eSetBits);
			}
			while(HAL_GPIO_ReadPin(GPIOA,GPIO_PIN_1)==GPIO_PIN_RESET);
		}
    osDelay(10);
  }
  /* USER CODE END StartTaskSend */
}

/* USER CODE BEGIN Header_StartTaskReceive */
/**
* @brief Function implementing the TaskReceive thread.
* @param argument: Not used
* @retval None
*/
/* USER CODE END Header_StartTaskReceive */
void StartTaskReceive(void const * argument)
{
  /* USER CODE BEGIN StartTaskReceive */
	uint32_t notify_val=0,event_bit;
  /* Infinite loop */
  for(;;)
  {
   xTaskNotifyWait(0,0xFFFFFFFF,&notify_val,portMAX_DELAY);
		if(notify_val & 0x01)
			event_bit |=0x01;
			if(notify_val & 0x02)
			event_bit |=0x02;
			if(event_bit==(0x01|0x02))
			{
			printf("任务通知模拟事件标志组成功\r\n");
				event_bit=0;
			}
    osDelay(1);
  }
  /* USER CODE END StartTaskReceive */
}

/* Private application code --------------------------------------------------*/
/* USER CODE BEGIN Application */

/* USER CODE END Application */

4）邮箱代码

/* USER CODE BEGIN Header */
/**
  ******************************************************************************
  * File Name          : freertos.c
  * Description        : Code for freertos applications
  ******************************************************************************
  * @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 "FreeRTOS.h"
#include "task.h"
#include "main.h"
#include "cmsis_os.h"

/* Private includes ----------------------------------------------------------*/
/* USER CODE BEGIN Includes */
#include <stdio.h>
/* 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 Variables */

/* USER CODE END Variables */
osThreadId TaskSendHandle;
osThreadId TaskReceiveHandle;

/* Private function prototypes -----------------------------------------------*/
/* USER CODE BEGIN FunctionPrototypes */

/* USER CODE END FunctionPrototypes */

void StartTaskSend(void const * argument);
void StartTaskReceive(void const * argument);

void MX_FREERTOS_Init(void); /* (MISRA C 2004 rule 8.1) */

/* GetIdleTaskMemory prototype (linked to static allocation support) */
void vApplicationGetIdleTaskMemory( StaticTask_t **ppxIdleTaskTCBBuffer, StackType_t **ppxIdleTaskStackBuffer, uint32_t *pulIdleTaskStackSize );

/* USER CODE BEGIN GET_IDLE_TASK_MEMORY */
static StaticTask_t xIdleTaskTCBBuffer;
static StackType_t xIdleStack[configMINIMAL_STACK_SIZE];

void vApplicationGetIdleTaskMemory( StaticTask_t **ppxIdleTaskTCBBuffer, StackType_t **ppxIdleTaskStackBuffer, uint32_t *pulIdleTaskStackSize )
{
  *ppxIdleTaskTCBBuffer = &xIdleTaskTCBBuffer;
  *ppxIdleTaskStackBuffer = &xIdleStack[0];
  *pulIdleTaskStackSize = configMINIMAL_STACK_SIZE;
  /* place for user code */
}
/* USER CODE END GET_IDLE_TASK_MEMORY */

/**
  * @brief  FreeRTOS initialization
  * @param  None
  * @retval None
  */
void MX_FREERTOS_Init(void) {
  /* USER CODE BEGIN Init */

  /* USER CODE END Init */

  /* USER CODE BEGIN RTOS_MUTEX */
  /* add mutexes, ... */
  /* USER CODE END RTOS_MUTEX */

  /* USER CODE BEGIN RTOS_SEMAPHORES */
  /* add semaphores, ... */
  /* USER CODE END RTOS_SEMAPHORES */

  /* USER CODE BEGIN RTOS_TIMERS */
  /* start timers, add new ones, ... */
  /* USER CODE END RTOS_TIMERS */

  /* USER CODE BEGIN RTOS_QUEUES */
  /* add queues, ... */
  /* USER CODE END RTOS_QUEUES */

  /* Create the thread(s) */
  /* definition and creation of TaskSend */
  osThreadDef(TaskSend, StartTaskSend, osPriorityNormal, 0, 128);
  TaskSendHandle = osThreadCreate(osThread(TaskSend), NULL);

  /* definition and creation of TaskReceive */
  osThreadDef(TaskReceive, StartTaskReceive, osPriorityNormal, 0, 128);
  TaskReceiveHandle = osThreadCreate(osThread(TaskReceive), NULL);

  /* USER CODE BEGIN RTOS_THREADS */
  /* add threads, ... */
  /* USER CODE END RTOS_THREADS */

}

/* USER CODE BEGIN Header_StartTaskSend */
/**
  * @brief  Function implementing the TaskSend thread.
  * @param  argument: Not used
  * @retval None
  */
/* USER CODE END Header_StartTaskSend */
void StartTaskSend(void const * argument)
{
  /* USER CODE BEGIN StartTaskSend */
  /* Infinite loop */
  for(;;)
  {
		if(HAL_GPIO_ReadPin(GPIOA,GPIO_PIN_0)==GPIO_PIN_RESET)
		{
		osDelay(20);
			if(HAL_GPIO_ReadPin(GPIOA,GPIO_PIN_0)==GPIO_PIN_RESET)
			{
      printf("按键1按下\r\n");
				xTaskNotify(TaskReceiveHandle,1,eSetValueWithOverwrite);
			}
			while(HAL_GPIO_ReadPin(GPIOA,GPIO_PIN_0)==GPIO_PIN_RESET);
		}
		
			if(HAL_GPIO_ReadPin(GPIOA,GPIO_PIN_1)==GPIO_PIN_RESET)
		{
		osDelay(20);
			if(HAL_GPIO_ReadPin(GPIOA,GPIO_PIN_1)==GPIO_PIN_RESET)
			{
      printf("按键2按下\r\n");
				xTaskNotify(TaskReceiveHandle,2,eSetValueWithOverwrite);
			}
			while(HAL_GPIO_ReadPin(GPIOA,GPIO_PIN_1)==GPIO_PIN_RESET);
		}
    osDelay(10);
  }
  /* USER CODE END StartTaskSend */
}

/* USER CODE BEGIN Header_StartTaskReceive */
/**
* @brief Function implementing the TaskReceive thread.
* @param argument: Not used
* @retval None
*/
/* USER CODE END Header_StartTaskReceive */
void StartTaskReceive(void const * argument)
{
  /* USER CODE BEGIN StartTaskReceive */
	uint32_t notify_val=0,event_bit;
  /* Infinite loop */
  for(;;)
  {
   xTaskNotifyWait(0,0xFFFFFFFF,&notify_val,portMAX_DELAY);
	printf("接收到的通知值为：%d\r\n",notify_val);
    osDelay(1);
  }
  /* USER CODE END StartTaskReceive */
}

/* Private application code --------------------------------------------------*/
/* USER CODE BEGIN Application */

/* USER CODE END Application */