FreeRTOS学习笔记-事件组

概述

事件组允许任务在“阻塞”状态下等待一个或多个事件的组合发生。当事件发生时，事件组解除阻塞所有等待同一事件或事件组合的任务。

关键函数说明

#include "freertos/event_groups.h"

//创建事件组
EventGroupHandle_t xEventGroupCreate( void );// 如果configUSE_16_BIT_TICKS==1事件组为8bit，否则为24bit

//设置事件bit
EventBits_t xEventGroupSetBits(
			EventGroupHandle_t xEventGroup,//事件组句柄
			const EventBits_t uxBitsToSet //要设置的事件组bit
			);

//等待事件bit
EventBits_t xEventGroupWaitBits( 
		const EventGroupHandle_t xEventGroup,//事件组句柄
		const EventBits_t uxBitsToWaitFor,//需要等待的bit
		const BaseType_t xClearOnExit,//函数执行完是否清除等待bit，pdTRUE==clear ；pdFALSE==不清除
		const BaseType_t xWaitForAllBits,//pdTRUE== 所有等待bit被设置时返回（AND）；pdFALSE==任意1个等待bit被设置时返回（OR）
		TickType_t xTicksToWait //等待时间
		);

//事件同步
EventBits_t xEventGroupSync( 
		EventGroupHandle_t xEventGroup,//事件组句柄
		const EventBits_t uxBitsToSet,//被设置的bit
		const EventBits_t uxBitsToWaitFor,//等待的bit
		TickType_t xTicksToWait );//等待时间
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课程示例

事件组等待(Event Group Wait)

#include 
#include "sdkconfig.h"
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "esp_system.h"
#include "esp_spi_flash.h"
#include "freertos/semphr.h"
#include "freertos/event_groups.h"

#define BIT_0 (1 << 0)
#define BIT_4 (1 << 4)

EventGroupHandle_t EventGroup1;

void mytask1(void *pvParameter)
{
    EventBits_t uxBits;
    while (1)
    {
        uxBits = xEventGroupWaitBits(
            EventGroup1,    /* The event group being tested. */
            BIT_0 | BIT_4,  /* The bits within the event group to wait for. */
            pdTRUE,         /* Clear */
            pdFALSE,        /* OR-- Don't wait for both bits, either bit will do. */
            portMAX_DELAY); /* */
        if ((uxBits & (BIT_0 | BIT_4)) == (BIT_0 | BIT_4))
        {
            /* bit 0 和 4 都被设置*/
            printf("task1 bit0 and bit4 is set \n");
            printf("----------------------------\n");
        }
        else if ((uxBits & BIT_0) != 0)
        {
            /* 仅BIT_0 was set. */
            printf("task1 just bit0 is set \n");
            printf("----------------------------\n");
        }
        else if ((uxBits & BIT_4) != 0)
        {
            /* 仅BIT_4 was set. */
            printf("task1 just bit4 is set \n");
            printf("----------------------------\n");
        }
        else
        {
            /*超时*/
            printf("task1 wait time out \n");
            printf("----------------------------\n");
        }
    }
}

void mytask2(void *pvParameter)
{
    vTaskDelay(2000 / portTICK_PERIOD_MS);
    xEventGroupSetBits(EventGroup1, BIT_0 | BIT_4);
    printf("task2 set bit0 and bit4 \n");
    vTaskDelay(2000 / portTICK_PERIOD_MS);
    xEventGroupSetBits(EventGroup1, BIT_0);
    printf("task2 set bit0 \n");
    vTaskDelay(2000 / portTICK_PERIOD_MS);
    xEventGroupSetBits(EventGroup1, BIT_4);
    printf("task2 set bit4 \n");
    vTaskDelay(2000 / portTICK_PERIOD_MS);
    vTaskDelete(NULL);
}

void app_main(void)
{

    EventGroup1 = xEventGroupCreate(); //创建事件组1
    if (EventGroup1 != NULL)
    {
        xTaskCreatePinnedToCore(mytask1, "mytask1", 1024 * 5, NULL, 1, NULL, 0); //最后一个参数是Core ID
        xTaskCreatePinnedToCore(mytask2, "mytask2", 1024 * 5, NULL, 1, NULL, 0);
    }
}

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效果

task2 set bit0 and bit4 
task1 bit0 and bit4 is set 
----------------------------
task2 set bit0 
task1 just bit0 is set 
----------------------------
task2 set bit4 
task1 just bit4 is set 
----------------------------
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任务2每隔2s设置一次事件bit，任务1均能正常接收。

事件组同步(Event Group Sync)

#include 
#include "sdkconfig.h"
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "esp_system.h"
#include "esp_spi_flash.h"
#include "freertos/semphr.h"
#include "freertos/event_groups.h"

#define TASK_0_BIT (1 << 0)
#define TASK_1_BIT (1 << 1)
#define TASK_2_BIT (1 << 2)
#define ALL_SYNC_BITS (TASK_0_BIT | TASK_1_BIT | TASK_2_BIT)

EventGroupHandle_t EventGroup1;

void mytask0(void *pvParameter)
{
    while (1)
    {
        vTaskDelay(1000 / portTICK_PERIOD_MS);
        xEventGroupSync(
            EventGroup1,    //事件组句柄
            TASK_0_BIT,     //被设置的bit
            ALL_SYNC_BITS,  //等待的bit
            portMAX_DELAY); //等待时间
        printf("task0 sync over \n");
        vTaskDelay(5000 / portTICK_PERIOD_MS);
    }
}
void mytask1(void *pvParameter)
{
    while (1)
    {
        vTaskDelay(2000 / portTICK_PERIOD_MS);
        xEventGroupSync(
            EventGroup1,    //事件组句柄
            TASK_1_BIT,     //被设置的bit
            ALL_SYNC_BITS,  //等待的bit
            portMAX_DELAY); //等待时间
        printf("task1 sync over \n");
        vTaskDelay(5000 / portTICK_PERIOD_MS);
    }
}
void mytask2(void *pvParameter)
{
    while (1)
    {
        vTaskDelay(3000 / portTICK_PERIOD_MS);
        xEventGroupSync(
            EventGroup1,    //事件组句柄
            TASK_2_BIT,     //被设置的bit
            ALL_SYNC_BITS,  //等待的bit
            portMAX_DELAY); //等待时间
        printf("task2 sync over \n");
        vTaskDelay(5000 / portTICK_PERIOD_MS);
    }
}

void app_main(void)
{

    EventGroup1 = xEventGroupCreate(); //创建事件组1
    if (EventGroup1 != NULL)
    {
        xTaskCreatePinnedToCore(mytask0, "mytask0", 1024 * 5, NULL, 6, NULL, 0); //最后一个参数是Core ID
        xTaskCreatePinnedToCore(mytask1, "mytask1", 1024 * 5, NULL, 6, NULL, 0);
        xTaskCreatePinnedToCore(mytask2, "mytask2", 1024 * 5, NULL, 6, NULL, 0);
    }
    int i = 1;
    while (1)
    {
        vTaskDelay(1000 / portTICK_PERIOD_MS);
        printf("%d \n", i);
        i++;
    }
}

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效果

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task2 sync over
task0 sync over
task1 sync over
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task2 sync over
task0 sync over
task1 sync over
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task2 sync over
task0 sync over
task1 sync over
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主程序循环打印秒计数，可见任务1、2、3在第3s进行了同步，反复运行。