#include<reg52.h>

unsigned char code LedChar[] = {  // 数码管真值表
    0xC0, 0xF9, 0xA4, 0xB0, 0x99, 0x92, 0x82, 0xF8,
    0x80, 0x90, 0x88, 0x83, 0xC6, 0xA1, 0x86, 0x8E
};
unsigned char LedBuff[6] = {  // 数码管缓存数组
    0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF
};
unsigned int cnt = 0;  // 中断计数器

void main() {
    unsigned long sec = 0, base = 1; // 秒数, 秒数的基数, 十进制
    unsigned int j = 0; // 数码管模块的编号(0-5)  
    P1 = 0x00;    //使能U3，选择控制数码管
    TMOD = 0x01;  // 定时器工作模式1
    TH0 = 0xFC;   // 设定定时器的计时长度为0.02秒
    TL0 = 0x67;
    TR0 = 1;       
    ET0 = 1;
    EA = 1;
    while(1) {
        if(cnt >= 1000) {
            cnt = 0;
            sec++;
            for(j = 0; j < 6; j++) {
                LedBuff[j] = LedChar[sec/base%10];  // 带前导0
                //sec/base ? (LedBuff[j] = LedChar[sec/base%10]) : (LedBuff[j] = 0xFF); // 不带前导0 
                base *= 10;
            }
        }
        base = 1;           
    }
}

unsigned char i = 0;

void InterruptTimer0() interrupt 1 {
    TH0 = 0xFC;  //重新加载初值
    TL0 = 0x67;
    cnt++;       //中断次数计数值加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: P1 = 0x08, i++, P0 = LedBuff[0]; break;
        case 1: P1 = 0x09, i++, P0 = LedBuff[1]; break;
        case 2: P1 = 0x0A, i++, P0 = LedBuff[2]; break;
        case 3: P1 = 0x0B, i++, P0 = LedBuff[3]; break;
        case 4: P1 = 0x0C, i++, P0 = LedBuff[4]; break;
        case 5: P1 = 0x0D, i=0, P0 = LedBuff[5]; break;
        default: break;
    }
}