#include <reg52.h>

sbit LED = P0^;

unsigned int vT = ;

void main()

{

    LED = ;

    TMOD = 0x01;

    TH0 = 0x3C;    // 计数初值3CB0H = 15536 (65536-15536=50000 * 1us = 50ms)

    TL0 = 0xB0;

    ET0 = ;       // EA即IE^1 等于1时申请中断定时器0中断打开

    EA = ;        // 总中断打开

    TR0 = ;       // 启动定时器0

    while();

}

void MyInterrupt(void) interrupt     // 中断服务程序

{

    vT++;

    if (vT == )       // 20 * 50ms = 1000ms = 1s

    {

        LED = !LED;

        vT = ;

        TH0 = 0x3C;    // 恢复计数初值

        TL0 = 0xB0;

    }

}