UC/OS II多任務切換例程

#include “config.h”

#define TaskStkLengh 64

OS_STK TaskStk [TaskStkLengh];

OS_STK TaskStk1 [TaskStkLengh];

OS_STK TaskStk2 [TaskStkLengh];

OS_EVENT *TASK1;

OS_EVENT *TASK2;

OS_EVENT *TASK3;

void Task0(void *pdata); //Task0 ÈÎÎñ0

void Task1(void *pdata);

void Task2(void *pdata);

uint8 err;

void UART0_Ini(void)

{ uint16 Fdiv;

U0LCR = 0x83;

Fdiv = (Fpclk / 16) / UART_BPS;

U0DLM = Fdiv / 256;

U0DLL = Fdiv % 256;

U0LCR = 0x03;

}

void UART0_SendByte(uint8 data)

{ U0THR = data; // ·ËÍÊý¾Ý

while( (U0LSR0x40)==0 ); // µÈ´ýÊý¾Ý

}

int main (void)

{

OSInit

();

OSTaskCreate (Task0,(void *)0, TaskStk[TaskStkLengh - 1], 0);

TASK1= OSSemCreate(0);

TASK2= OSSemCreate(0);

TASK3= OSSemCreate(0);

TargetInit();

OSStart ();

return 0;

}

/*******************************************************************************************

** Task0 ÈÎÎñ0

*******************************************************************************************/

void Task0 (void *pdata)

{

UART0_Ini();

OSTaskCreate(Task1, (void *)0, TaskStk1[TaskStkLengh-1], 9);

OSTaskCreate(Task2, (void *)0, TaskStk2[TaskStkLengh-1], 10);

OSSemPost(TASK1);

for (;;)

{

OSSemPend(TASK1,10,err

if(err==OS_NO_ERR)

{

UART0_SendByte(0x01);

OSSemPost(TASK2);

}

}

}

/******************************************************************************************* Task1 ÈÎÎñ1

*******************************************************************************************/

void Task1 (void *pdata)

{

UART0_Ini();

for (;;)

{

OSSemPend(TASK2,10,err);

if(err==OS_NO_ERR)

{

UART0_SendByte(0x02);

OSSemPost(TASK3);

}

}

}

void Task2 (void *pdata)

{

UART0_Ini();

for (;;)

{

OSSemPend(TASK3,10,err);//»

if(err==OS_NO_ERR)

{

UART0_SendByte(0x03);

OSSemPost(TASK1);

}

}

}

三個任務分別通過UART0輸出0X01,0X02,0X03,可以學習理解信號量的基本用法及多任務的調度方法.