FreeRTOS软件定时器

API函数

//创建
TimerHandle_t xTimerCreate( const char * const pcTimerName,
                            const TickType_t xTimerPeriodInTicks,
                            const UBaseType_t uxAutoReload,
                            void * const pvTimerID,
                            TimerCallbackFunction_t pxCallbackFunction )

//开始
#define xTimerStart( xTimer, xTicksToWait ) xTimerGenericCommand( ( xTimer ), tmrCOMMAND_START, 
    ( xTaskGetTickCount() ), NULL, ( xTicksToWait ) )
BaseType_t xTimerGenericCommand( TimerHandle_t xTimer, const BaseType_t xCommandID, 
    const TickType_t xOptionalValue, BaseType_t * const pxHigherPriorityTaskWoken, 
    const TickType_t xTicksToWait )

//停止
#define xTimerStop( xTimer, xTicksToWait ) xTimerGenericCommand( ( xTimer ), tmrCOMMAND_STOP, 
    0U, NULL, ( xTicksToWait ) )

举例

void start_task(void *pvParameters)
{
    //创建软件周期定时器。周期1s(1000个时钟节拍)，周期模式
    AutoReloadTimer_Handle=xTimerCreate((const char*        )"AutoReloadTimer",
                                        (TickType_t         )1000,
                                        (UBaseType_t        )pdTRUE,
                                        (void*              )1,
                                        (TimerCallbackFunction_t)AutoReloadCallback);

    //创建单次定时器。周期2s(2000个时钟节拍)，单次模式
    OneShotTimer_Handle=xTimerCreate((const char*           )"OneShotTimer",
                                     (TickType_t            )2000,
                                     (UBaseType_t           )pdFALSE,
                                     (void*                 )2,
                                     (TimerCallbackFunction_t)OneShotCallback);
}

//周期定时器的回调函数
void AutoReloadCallback(TimerHandle_t xTimer)
{
    static u8 tmr1_num=0;
    tmr1_num++;     //周期定时器执行次数加1
    printf("AutoReloadCallback %d
", tmr1_num);
}

//单次定时器的回调函数
void OneShotCallback(TimerHandle_t xTimer)
{
    static u8 tmr2_num = 0;
    tmr2_num++;     //单次定时器执行次数加1
    printf("OneShotCallback %d
", tmr2_num);
}

void timercontrol_task(void *pvParameters)
{
    while(1)
    {
        key = KEY_Scan(0);
        switch(key)
        {
            case WKUP_PRES:     //当key_up按下的话打开周期定时器
                xTimerStart(AutoReloadTimer_Handle,0);  //开启周期定时器
                printf("开启定时器1
");
                break;
            case KEY0_PRES:     //当key0按下的话打开单次定时器
                xTimerStart(OneShotTimer_Handle,0);     //开启单次定时器
                printf("开启定时器2
");
                break;
            case KEY1_PRES:     //当key1按下话就关闭定时器
                xTimerStop(AutoReloadTimer_Handle,0);   //关闭周期定时器
                xTimerStop(OneShotTimer_Handle,0);      //关闭单次定时器
                printf("关闭定时器1和2
");
                break;  
        }

        vTaskDelay(10); //延时10ms，也就是10个时钟节拍
    }
}

实验现象