期中测试（ 制作一个秒表计时器 ）

#include<reg52.h>
#define LED  P0
sbit KEY1 =P1^0;
sbit KEY2 =P1^4;
unsigned int i = 0;
unsigned char n = 0;
unsigned char LED_NUM[] = {0xc0,0xf9,0xa4,0xb0,                           0x99,0x92,0x82,0xf8,                           0x80,0x90,0x88,0x83,                           0xc6,0xa1,0x86,0x8e};
void INT_T0(void)
{
    TMOD = 0X01; //打开定时器0 ，使用模式1定时
    TH0 = 0XFC;
    TL0    = 0X18; //初始值
    EA = 1;//打开总开关
    ET0 = 1;//打开中断T0开关
}
void main(void)
{    
    INT_T0();
    TR0 = 1; //定时功能打开
    while(1)
    {
        if(KEY1 ==0)
        {
            TR0 = 1;
        }        
        if(KEY2 ==0)
        {
            i=0;
            n=0;

        }            
    }
}
void time0(void) interrupt 1 
{
    TH0 = 0XFC;
    TL0    = 0X18; //初始值
    if(i < 1000)
    {
        i++;
    }
    else
    {
        LED = LED_NUM[n];
        if(n<16)
        {
            n++;
        }
        else
        {
            n=0;
        }
            i=0;        
    }
}