UCOSIII信号量

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信号量通常分为两种

二进制信号量

计数型信号量

二进制信号量

二进制信号量只能取0和1两个值

计数型信号量

计数型信号量的范围由OS_SEM_CTR决定。OS_SEM_CTR可以为8位，16位和32位

API函数

//创建

void OSSemCreate (OS_SEM *p_sem,

                  CPU_CHAR *p_name,

                  OS_SEM_CTR cnt,

                  OS_ERR *p_err);

//删除

OS_OBJ_QTY OSSemDel (OS_SEM *p_sem,

                     OS_OPT opt,

                     OS_ERR *p_err);

//等待-1

OS_SEM_CTR OSSemPend (OS_SEM *p_sem,

                      OS_TICK timeout,

                      OS_OPT opt,

                      CPU_TS *p_ts,

                      OS_ERR *p_err);

//取消等待

OS_OBJ_QTY OSSemPendAbort (OS_SEM *p_sem,

                           OS_OPT opt,

                           OS_ERR *p_err);

//释放+1

OS_SEM_CTR OSSemPost (OS_SEM *p_sem,

                      OS_OPT opt,

                      OS_ERR *p_err);

//设置值

void OSSemSet (OS_SEM *p_sem,

               OS_SEM_CTR cnt,

               OS_ERR *p_err);

应用举例

void start_task(void *p_arg)

{

    OS_CRITICAL_ENTER();    //进入临界区

    //创建一个信号量

    OSSemCreate ((OS_SEM*   )&MY_SEM,

                 (CPU_CHAR* )"MY_SEM",

                 (OS_SEM_CTR)1,

                 (OS_ERR*   )&err);

    //创建TASK1任务

    OSTaskCreate((OS_TCB    * )&Task1_TaskTCB,

                 (CPU_CHAR  * )"Task1 task",

                 (OS_TASK_PTR )task1_task,

                 (void      * )0,

                 (OS_PRIO     )TASK1_TASK_PRIO,

                 (CPU_STK   * )&TASK1_TASK_STK[0],

                 (CPU_STK_SIZE)TASK1_STK_SIZE/10,

                 (CPU_STK_SIZE)TASK1_STK_SIZE,

                 (OS_MSG_QTY  )0,

                 (OS_TICK     )0,

                 (void      * )0,

                 (OS_OPT      )OS_OPT_TASK_STK_CHK|OS_OPT_TASK_STK_CLR,

                 (OS_ERR    * )&err);           

    //创建TASK2任务

    OSTaskCreate((OS_TCB    * )&Task2_TaskTCB,

                 (CPU_CHAR  * )"Task2 task",

                 (OS_TASK_PTR )task2_task,

                 (void      * )0,

                 (OS_PRIO     )TASK2_TASK_PRIO,

                 (CPU_STK   * )&TASK2_TASK_STK[0],

                 (CPU_STK_SIZE)TASK2_STK_SIZE/10,

                 (CPU_STK_SIZE)TASK2_STK_SIZE,

                 (OS_MSG_QTY  )0,

                 (OS_TICK     )0,

                 (void      * )0,

                 (OS_OPT      )OS_OPT_TASK_STK_CHK|OS_OPT_TASK_STK_CLR,

                 (OS_ERR    * )&err);                

    OS_CRITICAL_EXIT(); //退出临界区

}

//任务1的任务函数

void task1_task(void *p_arg)

{

    OS_ERR err;

    u8 task1_str[]="First task Running!";

    while(1)

    {

        printf("\r\n任务1:\r\n");

        OSSemPend(&MY_SEM,0,OS_OPT_PEND_BLOCKING,0,&err);   //请求信号量

        memcpy(share_resource,task1_str,sizeof(task1_str)); //向共享资源区拷贝数据

        printf("%s\r\n",share_resource);    //串口输出共享资源区数据

        OSSemPost (&MY_SEM,OS_OPT_POST_1,&err);             //发送信号量

        OSTimeDlyHMSM(0,0,1,0,OS_OPT_TIME_PERIODIC,&err);   //延时1s

    }

}

//任务2的任务函数

void task2_task(void *p_arg)

{

    OS_ERR err;

    u8 task2_str[]="Second task Running!";

    while(1)

    {

        printf("\r\n任务2:\r\n");

        OSSemPend(&MY_SEM,0,OS_OPT_PEND_BLOCKING,0,&err);   //请求信号量

        memcpy(share_resource,task2_str,sizeof(task2_str)); //向共享资源区拷贝数据

        printf("%s\r\n",share_resource);    //串口输出共享资源区数据

        OSSemPost (&MY_SEM,OS_OPT_POST_1,&err);             //发送信号量

        OSTimeDlyHMSM(0,0,1,0,OS_OPT_TIME_PERIODIC,&err);   //延时1s

    }

}