利用一个数码管和两个开关实现秒表0-9功能

#include<reg52.h>
#define LED_ALL P0
sbit LED = P0^0;
sbit key1 = P1^0;
sbit key2 = P1^1;
unsigned int i = 0;
unsigned n = 0;
unsigned char num[] = {0xc0,0xf9,0xa4,0xb0,0x99,0x92,0x82,0xf8,0x80,0x90,0xff};
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;
        else
            TR0 = 0;        
        if(key2==0)
            n=0;
        LED_ALL=num[n];
    }
}
void time0(void) interrupt 1 
{
    TH0 = 0XFC;
    TL0    = 0X18; //初始值
    if(i < 1000)
    {
        i++;
    }
    else
    {
        P0 = num[n];
        i = 0;
        if(n<9)
            n++;
        else
            n=0;    
    }
}