数码管从999999倒计时

//1.
#include <reg52.h>

sbit ADDR0 = P1^0;
sbit ADDR1 = P1^1;
sbit ADDR2 = P1^2;
sbit ADDR3 = P1^3;
sbit ENLED = P1^4;

unsigned char code LedChar[] = {  //数码管显示字符转换表
    0xC0, 0xF9, 0xA4, 0xB0, 0x99, 0x92, 0x82, 0xF8,
    0x80, 0x90, 0x88, 0x83, 0xC6, 0xA1, 0x86, 0x8E
};
unsigned char LedBuff[6] = {  //数码管显示缓冲区，初值0xFF确保启动时都不亮
    0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF
};
unsigned char i = 0;   //动态扫描的索引
unsigned int cnt = 0;  //记录T1中断次数
unsigned char flag1s = 0;  //1秒定时标志

void main()
{
    char j;  //循环变量
    unsigned long sec = 1000000;  //记录经过的秒数，倒计时初值为999999+1
    unsigned char buf[6];   //中间转换缓冲区

    EA = 1;       //使能总中断
    ENLED = 0;    //使能U3
    ADDR3 = 1;    //因为需要动态改变ADDR0-2的值，所以不需要再初始化了
    TMOD = 0x10;  //设置T1为模式1
    TH1  = 0xFC;  //为T1赋初值0xFC67，定时1ms
    TL1  = 0x67;
    ET1  = 1;     //使能T1中断
    TR1  = 1;     //启动T1
   
    while (1)
    {
        if (flag1s == 1)  //判断1秒定时标志
        {
            flag1s = 0;   //1秒定时标志清零
            sec--;        //秒计数自减1
            //将sec按十进制位从低到高依次提取到buf数组中
            buf[0] = sec%10;
            buf[1] = sec/10%10;
            buf[2] = sec/100%10;
            buf[3] = sec/1000%10;
            buf[4] = sec/10000%10;
            buf[5] = sec/100000%10;
            //从最高为开始，遇到0不显示，遇到非0退出循环
            for (j=5; j>=1; j--)
            {
                if (buf[j] == 0)
                    LedBuff[j] = 0xFF;
                else
                    break;
            }
            //将剩余的有效数字位如实转换
            for ( ; j>=0; j--)  //for()起始未对j操作，j即保持上个循环结束时的值
            {
                LedBuff[j] = LedChar[buf[j]];
            }
        }
    }
}
/* 定时器1中断服务函数 */
void InterruptTimer1() interrupt 3
{
    TH1 = 0xFC;  //重新加载初值
    TL1 = 0x67;
    cnt++;       //中断次数计数值加1
    if (cnt >= 1000)  //中断1000次即1秒
    {
        cnt = 0;      //清零计数值以重新开始下1秒计时
        flag1s = 1;   //设置1秒定时标志为1
    }
    //以下代码完成数码管动态扫描刷新
    P0 = 0xFF;   //显示消隐
    switch (i)
    {
        case 0: ADDR2=0; ADDR1=0; ADDR0=0; i++; P0=LedBuff[0]; break;
        case 1: ADDR2=0; ADDR1=0; ADDR0=1; i++; P0=LedBuff[1]; break;
        case 2: ADDR2=0; ADDR1=1; ADDR0=0; i++; P0=LedBuff[2]; break;
        case 3: ADDR2=0; ADDR1=1; ADDR0=1; i++; P0=LedBuff[3]; break;
        case 4: ADDR2=1; ADDR1=0; ADDR0=0; i++; P0=LedBuff[4]; break;
        case 5: ADDR2=1; ADDR1=0; ADDR0=1; i=0; P0=LedBuff[5]; break;
        default: break;
    }
}

//2.

//#include <reg52.h>
//sbit  ADDR0=P1^0;
//sbit  ADDR1=P1^1;
//sbit  ADDR2=P1^2;
//sbit  ADDR3=P1^3;
//sbit  ENLED=P1^4;
//unsigned char code LedChar[]={
// 0x90,0x80,0xF8,0x82,0x92,0x99,0xB0,0xA4,0xF9,0xC0
//};
//unsigned char LedBuff[6]={
//  0xFF,0xFF,0xFF,0xFF,0xFF,0xFF
//};
//unsigned char i=0;
//unsigned int cnt=0;
//
//void main1()
//  {
//  unsigned char sec=0;
//  unsigned int a=0;
//    EA=1;
//     ENLED=0;
//  ADDR3=1;
//  TMOD=0x01;
//  TH0=0xFC;
//  TL0=0x67;
//
//  ET0=1;
//  TR0=1;
//
//  while(1)
//  {
//     if(cnt>=1000)
//     {
//        cnt=0;
//     sec++ ;
//     LedBuff[0]=LedChar[sec%10];
//     LedBuff[1]=LedChar[sec/10%10];
//     LedBuff[2]=LedChar[sec/100%10];
//     LedBuff[3]=LedChar[sec/1000%10];
//     LedBuff[4]=LedChar[sec/10000%10];
//     LedBuff[5]=LedChar[sec/100000%10];
//     }
//  
//  }
//
//  }
//  void InterruptTimer() interrupt 1
//  {
//     TH0=0xFC;
//  TL0=0x67;
//  cnt++;
//
//  P0=0xFF;
//
//  switch (i)
//  {
//  case 0:ADDR2=0;ADDR1=0;ADDR0=0;i++;P0=LedBuff[0];break;
//  case 1:ADDR2=0;ADDR1=0;ADDR0=1;i++;P0=LedBuff[1];break;
//  case 2:ADDR2=0;ADDR1=1;ADDR0=0;i++;P0=LedBuff[2];break;
//  case 3:ADDR2=0;ADDR1=1;ADDR0=1;i++;P0=LedBuff[3];break;
//  case 4:ADDR2=1;ADDR1=0;ADDR0=0;i++;P0=LedBuff[4];break;
//  case 5:ADDR2=1;ADDR1=0;ADDR0=1;i=0;P0=LedBuff[5];break;
//  default: break;
//  }
// 
//  }