关于UCOSII任务间通信的疑问，

只看该作者 · 2014-7-20 15:30

本帖最后由 wang12zhe 于 2014-7-20 15:32 编辑

void Task_BEEP(void *p_arg)
{

(void)p_arg;
while(1)
{
LED1(ON);
OSTimeDlyHMSM(0,0,0,uLED1Time);
LED1(OFF);
OSTimeDlyHMSM(0,0,0,uLED1Time);


BEEP(BEEP_OFF);
OSSemPend(Fun_Semp,10,&err);  //???óD?o?á?

         BEEP(BEEP_ON);
         OSTimeDlyHMSM(0,0,1,500);

            BEEP(BEEP_OFF);
            OSTimeDlyHMSM(0,0,1,500);

  }
}

关于UCOSII任务间通信的疑问，
以信号量为例，代码如上，
OSSemPend(Fun_Semp,10,&err);

         BEEP(BEEP_ON);
         OSTimeDlyHMSM(0,0,1,500);

            BEEP(BEEP_OFF);
            OSTimeDlyHMSM(0,0,1,500);

获取信号量的超时时间为10，当因超时退出后会怎么执行呢，
是直接切换到更高优先级任务呢，还是接续执行本任务下边的代码呢
运行后没有发生信号量，蜂鸣器也会相，

是不是需要加一个判断，像这样
                     if(OS_NO_ERR==err)
                     {
                                    BEEP(BEEP_ON);
                                    OSTimeDlyHMSM(0,0,1,500);

                                    BEEP(BEEP_OFF);
                                    OSTimeDlyHMSM(0,0,1,500);
                     }

只看该作者 · 2014-7-20 21:00

*********************************************************************************************************
*                                        PEND ON SEMAPHORE
*
* Description: This function waits for a semaphore.
*
* Arguments  : pevent       is a pointer to the event control block associated with the desired
*                         semaphore.
*
*             timeout    is an optional timeout period (in clock ticks).  If non-zero, your task will
*                         wait for the resource up to the amount of time specified by this argument.
*                         If you specify 0, however, your task will wait forever at the specified
*                         semaphore or, until the resource becomes available (or the event occurs).
*
*             perr       is a pointer to where an error message will be deposited.  Possible error
*                         messages are:
*
*                         OS_ERR_NONE       The call was successful and your task owns the resource
*                                              or, the event you are waiting for occurred.
*                         OS_ERR_TIMEOUT    The semaphore was not received within the specified
*                                              'timeout'.
*                         OS_ERR_PEND_ABORT The wait on the semaphore was aborted.
*                         OS_ERR_EVENT_TYPE If you didn't pass a pointer to a semaphore.
*                         OS_ERR_PEND_ISR    If you called this function from an ISR and the result
*                                              would lead to a suspension.
*                         OS_ERR_PEVENT_NULL  If 'pevent' is a NULL pointer.
*                         OS_ERR_PEND_LOCKED  If you called this function when the scheduler is locked
*
* Returns : none
楼主可根据函数的返回值来判断.
比如:OS_ERR_NONE,表示等待的信号发生了.OS_ERR_TIMEOUT表示信号未发生,超时了.

只看该作者 · 2014-7-21 12:28

lapeno 发表于 2014-7-20 21:00
**************************************************************************************************** ...

首先很感谢你的回复，
其次，我看资料的时候有这样一段话，

我有疑问的地方就是
OSSemPend(Fun_Semp,10,&err);
         BEEP(BEEP_ON);
         OSTimeDlyHMSM(0,0,1,500);
            BEEP(BEEP_OFF);
            OSTimeDlyHMSM(0,0,1,500);如果任务等待时间超时后，下面的BEEP相关操作会执行吗？
根据我的理解应该不会得到执行，但测试发现却执行了。

只看该作者 · 2014-7-22 07:33

加上你这个判断就不会BEEP了，不加的话超时后当然会继续往下执行。
if(OS_NO_ERR==err)
                     {
                                    BEEP(BEEP_ON);
                                    OSTimeDlyHMSM(0,0,1,500);

                                    BEEP(BEEP_OFF);
                                    OSTimeDlyHMSM(0,0,1,500);
                     }

关于UCOSII任务间通信的疑问，

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