程序功能如下：
任务2给串口发送数据，然后给任务4发送消息。任务4收到消息后给串口发送数据。
当任务2不给任务4发送消息的时候，任务4就不给串口发送数据。
程序如下：
#include "STM32Lib\\stm32f10x.h"
#include "hal.h"
#include "UCOSII\\ucos_ii.h"
/******************************
** 任务堆栈
*******************************/
OS_STK Task0Stk[128];
OS_STK Task2Stk[128];
OS_STK Task3Stk[128];
OS_STK Task4Stk[128];
/******************************
任务函数
******************************/
void Task0 (void *p_arg);
void Task2 (void *p_arg);
void Task3 (void *p_arg);
void Task4 (void *p_arg);
OS_EVENT *sem;
OS_EVENT *mybox;
int main(void)
{
u8 os_err;
//由于使用UCOS,一下的初始化虽然可以在OS运行之前运行,但注意别使能任何中断.
ChipHalInit(); //片内硬件初始化
ChipOutHalInit(); //片外硬件初始化
OSInit(); //UCOS INIT~
os_err = OSTaskCreate( Task0, //第一个任务0
(void * ) 0, //不带参数
(OS_STK * )&Task0Stk[128 - 1], //堆栈指针
(INT8U ) 5 //优先级
);
OSStart();
while(1);
}
void Task0(void *p_arg)
{
u8 os_err;
char DATA_1[]="TASK1_ON\r\n";
OS_CPU_SysTickInit(); //使能SYSTICK中断
#if (OS_TASK_STAT_EN > 0)
OSStatInit(); /*这东西可以测量CPU使用量 */
#endif
//使能其他板上中断
//NVIC_Configuration();
os_err = OSTaskCreate( Task2, //任务1
&DATA_1, //不带参数
(OS_STK * )&Task2Stk[128 - 1], //堆栈指针
(INT8U ) 6 //优先级
);
os_err = OSTaskCreate( Task3, //任务2
(void * ) 0, //不带参数
(OS_STK * )&Task3Stk[128 - 1], //堆栈指针
(INT8U ) 7 //优先级
);
#if 1
os_err = OSTaskCreate( Task4, //任务3
(void * ) 0, //不带参数
(OS_STK * )&Task4Stk[128 - 1], //堆栈指针
(INT8U ) 8 //优先级
);
#endif
for(;;)
{
//OSTaskDel(2);
OSTimeDly(OS_TICKS_PER_SEC/2);
//USART1_Puts("TASK0_ON\r\n");
//LED1_ON;
//OSTimeDly(OS_TICKS_PER_SEC/10);
//LED1_OFF;
//USART1_Puts("TASK0_OFF\r\n");
}
}
void Task4(void *p_arg)
{
INT8U err;
for(;;)
{
//等待消息
OSMboxPend(mybox,0,&err);
USART1_Puts("4\r\n");
OSTimeDly(OS_TICKS_PER_SEC/10);
}
}
void Task2(void *p_arg)
{
INT8U err;
sem=OSSemCreate(0);//创建信号量
mybox=OSMboxCreate((void *)0); //创建消息
for(;;)
{
USART1_Puts("1\r\n");
OSTimeDly(OS_TICKS_PER_SEC/10);
//发送信号量
//OSSemPost(sem);
//发送消息
OSMboxPost(mybox,(void *)0);
OSTimeDly(OS_TICKS_PER_SEC/10);
}
}
void Task3(void *p_arg)
{
INT8U err;
for(;;)
{
//等待信号量
OSSemPend(sem,0,&err);
USART1_Puts("3\r\n");
OSTimeDly(OS_TICKS_PER_SEC/10);
}
}
几个关键函数的原型如下：
1、创建消息
/*
*********************************************************************************************************
* CREATE A MESSAGE MAILBOX
*
* Description: This function creates a message mailbox if free event control blocks are available.
*
* Arguments : pmsg is a pointer to a message that you wish to deposit in the mailbox. If
* you set this value to the NULL pointer (i.e. (void *)0) then the mailbox
* will be considered empty.
*
* Returns : != (OS_EVENT *)0 is a pointer to the event control clock (OS_EVENT) associated with the
* created mailbox
* == (OS_EVENT *)0 if no event control blocks were available
*********************************************************************************************************
*/
OS_EVENT *OSMboxCreate (void *pmsg)
2、发送消息
/*
*********************************************************************************************************
* POST MESSAGE TO A MAILBOX
*
* Description: This function sends a message to a mailbox
*
* Arguments : pevent is a pointer to the event control block associated with the desired mailbox
*
* pmsg is a pointer to the message to send. You MUST NOT send a NULL pointer.
*
* Returns : OS_ERR_NONE The call was successful and the message was sent
* OS_ERR_MBOX_FULL If the mailbox already contains a message. You can can only send one
* message at a time and thus, the message MUST be consumed before you
* are allowed to send another one.
* OS_ERR_EVENT_TYPE If you are attempting to post to a non mailbox.
* OS_ERR_PEVENT_NULL If 'pevent' is a NULL pointer
* OS_ERR_POST_NULL_PTR If you are attempting to post a NULL pointer
*
* Note(s) : 1) HPT means Highest Priority Task
*********************************************************************************************************
*/
INT8U OSMboxPost (OS_EVENT *pevent, void *pmsg)
3、等待消息
/*
*********************************************************************************************************
* 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
*********************************************************************************************************
*/
/*$PAGE*/
void OSSemPend (OS_EVENT *pevent, INT16U timeout, INT8U *perr)
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