此程序的电路图下载：http://www.51hei.com/f/ks51.pdf 只需要看数码管部分即可，其他部分可忽略掉.
#include <reg52.h> //stc89c51单片机头文件 typedef unsigned char uchar; typedef unsigned int uint; typedef unsigned long ulong; //变量类型宏定义 sbit ENLED = P1^4; sbit A 0 = P1^0;//管脚定义，作用为使能74hc138，让38译码器开始工作 sbit ADDR1 = P1^1; sbit ADDR2 = P1^2; sbit ADDR3 = P1^3; //管脚定义，作用为选定38译码器输出Y0-Y7，以便选定要显示的 （位选择） uchar led_char[] = { 0xC0, 0xF9, 0xA4, 0xB0, 0x99, 0x92, 0x82, 0xF8, 0x80, 0x90, 0x88, 0x83, 0xC6, 0xA1, 0x86, 0x8E}; //数码管字符真值表 0-F uchar led_buf[] = {0xFF,0xFF,0xFF,0xFF,0xFF,0xFF}; //数码管字符初始化，为关闭状态 uchar cnt = 0; //T1定时器溢出计数 uchar key = 0; //数码管动态扫描开关 ulong sec = 0; //时间变量 uchar hh = 8; //小时初值 uchar mm = 30; //分钟初值 uchar ss = 40; //秒数初值 void main() { sec = hh *3600 + mm * 60 + ss;//时间计算公式 EA = 1; //打开中断开关 ENLED = 0; ADDR3 = 1; //使能74hc138，让38译码器开始工作 TMOD = 0x10;//定时器工作模式设定 TH1 = 0xEE; = 0x00;//定时初值设置 ET1 = 1; //打开定时器1中断开关 TR1 = 1; //定时器1开始计时 while(1) { if(200 == cnt) { cnt = 0; sec++; if(sec < 86400) { led_buf[0] = led_char[sec%10]; led_buf[1] = led_char[sec%60/10]; led_buf[2] = led_char[sec%3600/60%10]; led_buf[3] = led_char[sec%3600/600]; led_buf[4] = led_char[sec/3600%10]; led_buf[5] = led_char[sec/3600/10]; //时间显示字符计算 } if(sec == 86400) { sec = 0; } } } } void interruptTimer0() interrupt 3 //定时器1中断服务程序 { TH1 = 0xEE; TL1 = 0x00; //定时初值设置 cnt++; P0 = 0xFF; //数码管消除鬼影 switch(key) { case 0: ADDR2 = 0;ADDR1 = 0;ADDR0 = 0;P0 = led_buf[0];key++;break; case 1: ADDR2 = 0;ADDR1 = 0;ADDR0 = 1;P0 = led_buf[1];key++;break; case 2: ADDR2 = 0;ADDR1 = 1;ADDR0 = 0;P0 = led_buf[2];key++;break; case 3: ADDR2 = 0;ADDR1 = 1;ADDR0 = 1;P0 = led_buf[3];key++;break; case 4: ADDR2 = 1;ADDR1 = 0;ADDR0 = 0;P0 = led_buf[4];key++;break; case 5: ADDR2 = 1;ADDR1 = 0;ADDR0 = 1;P0 = led_buf[5];key = 0;break; default:break; } //数码管动态扫描、显示时间值 } -电子元器件采购网（www.ruidan.com）是本土元器件目录分销商，采用“小批量、现货、样品”销售模式，致力于满足客户多型号、高质量、快速交付的采购需求。 自建高效智能仓储，拥有自营库存超过50,000种，提供一站式正品现货采购、个性化解决方案、选型替代等多元化服务。