FreeRTOS学习笔记-软件定时器

概述

软件定时器用于调度在未来的设定时间执行的函数，或以固定频率定期执行的函数。 由软件定时器执行的函数称为软件定时器的回调函数。软件定时器由FreeRTOS实现，不需要硬件支持，与硬件定时器或计数器无关。

关键函数说明

头文件

#include “freertos/timers.h”
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创建与删除软件定时器

//创建
TimerHandle_t xTimerCreate( 
		const char * const pcTimerName,//定时器名
		TickType_t xTimerPeriodInTicks,//定时周期，单位为Tick 如：pdMS_TO_TICKS( 500 ) == 500ms
		UBaseType_t uxAutoReload,//是否重载 pdTRUE / pdFALSE
		void * pvTimerID,//定时器ID指针
		TimerCallbackFunction_t pxCallbackFunction //回调函数指针
		);//返回值为所创建的定时器句柄
//删除
BaseType_t xTimerDelete( 
		TimerHandle_t xTimer, //定时器句柄
		TickType_t xTicksToWait//删除超时 
 		);
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软件定时器控制

这几个函数返回值均为： pdPASS / pdFAIL

//启动
BaseType_t xTimerStart( TimerHandle_t xTimer, TickType_t xTicksToWait );
//停止
BaseType_t xTimerStop( TimerHandle_t xTimer, TickType_t xTicksToWait );
//复位
BaseType_t xTimerReset( TimerHandle_t xTimer, TickType_t xTicksToWait );

//修改定时周期
BaseType_t xTimerChangePeriod( 
				TimerHandle_t xTimer,
				TickType_t xNewPeriod,//新的定时器周期
				TickType_t xTicksToWait 
				);
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xTicksToWait 说明：
FreeRTOS内核不提供计时功能，而是由 timer service (or daemon) 任务 实现，定时器API通过定时器队列发送命令到 timer service (or daemon) 任务 ，xTicksToWait 表示如果队列已满，则任务应保持阻塞状态，以等待队列腾出可用空间的最长时间。

获取定时器名字、周期和ID

//获取定时器名
const char * pcTimerGetName( TimerHandle_t xTimer );
//获取定时周期
TickType_t xTimerGetPeriod( TimerHandle_t xTimer );
//获取定时器ID
void *pvTimerGetTimerID( TimerHandle_t xTimer );
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课程示例

软件定时器的创建、启动、修改、复位、停止和删除测试

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

void timer1_callback(TimerHandle_t xTimer)
{
    printf("callback1 run \n");
}

void app_main(void)
{
    TimerHandle_t Timer1;
    int ID1 = 1;
    Timer1 = xTimerCreate("Timer1", pdMS_TO_TICKS(1000), pdTRUE, (void *)ID1, timer1_callback); //是否重载 pdTRUE / pdFALSE
    printf("creat timer1 period = 1s \n");

    //启动
    xTimerStart(Timer1, 0);
    printf("start timer1 \n");
    vTaskDelay(3000 / portTICK_PERIOD_MS);
    //复位
    for (int i = 0; i < 5; i++)
    {
        xTimerReset(Timer1, 0);
        printf("reset timer1 count = %d \n", i + 1);
        vTaskDelay(500 / portTICK_PERIOD_MS);
    }
    //修改定时周期
    xTimerChangePeriod(Timer1, pdMS_TO_TICKS(3000), 0);
    printf("change timer1 period = 3s \n");
    vTaskDelay(9000 / portTICK_PERIOD_MS);
    //停止
    xTimerStop(Timer1, 0);
    printf("stop timer1 \n");
    xTimerDelete(Timer1, 0);
    printf("delete timer1 \n");
}
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多个定时器控制同一个回调函数

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

void timer_callback(TimerHandle_t xTimer)
{
    char *timer_name;
    int *timer_id;
    timer_name = pcTimerGetName(xTimer);
    timer_id = (int *)pvTimerGetTimerID(xTimer);
    if (*timer_id == 1)
    {
        printf("%s_callback run ******* \n", timer_name);
    }
    if (*timer_id == 2)
    {
        printf("%s_callback run **************** \n", timer_name);
    }
}

void app_main(void)
{
    TimerHandle_t Timer1, Timer2;
    int ID1 = 1;
    int ID2 = 2;
    Timer1 = xTimerCreate("Timer1", pdMS_TO_TICKS(2000), pdTRUE, (void *)&ID1, timer_callback); //是否重载 pdTRUE / pdFALSE
    Timer2 = xTimerCreate("Timer2", pdMS_TO_TICKS(500), pdTRUE, (void *)&ID2, timer_callback);  //ID需要取地址

    xTimerStart(Timer1, 0);
    xTimerStart(Timer2, 0);
    vTaskDelay(10000 / portTICK_PERIOD_MS);

    xTimerStop(Timer1, 0);
    xTimerStop(Timer2, 0);
    printf("stop timer \n");
    xTimerDelete(Timer1, 0);
    xTimerDelete(Timer2, 0);
}
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效果

Timer2_callback run ****************
Timer2_callback run ****************
Timer2_callback run ****************
Timer1_callback run *******
Timer2_callback run ****************
Timer2_callback run ****************
Timer2_callback run ****************
Timer2_callback run ****************
Timer1_callback run *******
Timer2_callback run ****************
Timer2_callback run ****************
Timer2_callback run ****************
Timer2_callback run ****************
Timer1_callback run *******
Timer2_callback run ****************
Timer2_callback run ****************
Timer2_callback run ****************
Timer2_callback run ****************
Timer1_callback run *******
Timer2_callback run ****************
Timer2_callback run ****************
Timer2_callback run ****************
Timer2_callback run ****************
stop timer