程序设计计时器怎么编写程序

//Timer3初始化 下面是使用timer3做的500mA计时器，给你参考
void Timer3_Init(void)
{
//主时钟1s
INSCON|=(1< TL3=(unsigned char)T3CLK_500MS;
TH3=(unsigned char)(T3CLK_500MS>>8);
TF3=0;
switch(T3CLK_DIV)
{
case CLK_DIV_8:
T3PS0=1;
T3PS1=0; //1/8预分频
break;
case CLK_DIV_64:
T3PS0=0;
T3PS1=1; //1/64预分频
break;
case CLK_DIV_256:
T3PS0=1;
T3PS1=1; //1/256预分频
break;
default:
T3PS0=0;
T3PS1=0; //无预分频
}

T3CLKS1=0;
T3CLKS0=0;

TR3=1;
}
/************************************************/
/*Function Name:void Timer3_ISP(void)
/*Input:
/*Output:
/*Description:Timer3_ISP Interrupt
/*Data:
/************************************************/
extern void os_timer(void);
void Timer3_ISP(void) interrupt 11
{
uchar data temp_inscon;
temp_inscon=INSCON;
INSCON&=~(1< os_timer(); //这个中断500mA进来一次

INSCON=temp_inscon;
}

应该是不难的吧

timer 就是计时器