ESP32-S开发之 FreeRTOS EventGroup

发表于 2022-01-11 更新于 2022-12-11 分类于 28IoT 阅读次数：

本文基于ESP32-S开发之 FreeRTOS Semaphore

本文的主线简介 => 事件组

简介

Event groups can be used to synchronise tasks, creating what is often referred to as a task ‘rendezvous’. A task synchronisation point is a place in application code at which a task will wait in the Blocked state (not consuming any CPU time) until all the other tasks taking part in the synchronisation also reached their synchronisation point.

Usage Challenges

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Avoiding the creation of race conditions in the user's application

Avoiding non-determinism

事件组

1	vim main.cpp

#include <Arduino.h>

#define EV_1 (1<<0) // 1
#define EV_2 (1<<1) // 10
 
void TaskMain(void *pvParameters);
void Task1(void *pvParameters);
void Task2(void *pvParameters);

EventGroupHandle_t eventGroupHandle;
uint32_t events = 0;

void setup() {
    eventGroupHandle = xEventGroupCreate();

    xTaskCreate(&TaskMain, "Task Main", 1024, NULL, 1, NULL);
    xTaskCreate(&Task1, "Task 1", 1024, NULL, 1, NULL);
    xTaskCreate(&Task2, "Task 2", 1024, NULL, 1, NULL);
}

void loop() {
    // implicit invocation of vTaskStartScheduler
}

void TaskMain(void *pvParameters) {
    for( ;; ) {
        uint32_t events = 0;
        events |= EV_1;
        events |= EV_2;

        xEventGroupWaitBits(eventGroupHandle, events, pdTRUE, pdTRUE, portMAX_DELAY);
        printf("Task Main\r\n");
        xEventGroupClearBits(eventGroupHandle, events);
    }
}

void Task1(void *pvParameters) {
    for( ;; ) {
        vTaskDelay(1000 / portTICK_PERIOD_MS);
        printf("Task 1\r\n");
        xEventGroupSetBits(eventGroupHandle, EV_1);
    }
}

void Task2(void *pvParameters) {
    for( ;; ) {
        vTaskDelay(2000 / portTICK_PERIOD_MS);
        printf("Task 2\r\n");
        xEventGroupSetBits(eventGroupHandle, EV_2);
    }
}

参考

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