上學期寫的一個時鐘程序
可能很多可以優化的  
不過你可以參考一下

#include<reg51.h>

unsigned char shows1[10]={0x3f,0x06,0x5b,0x4f,0x66,0x6d,0x7d,0x07,0x7f,0x6f};
unsigned char shows2[10]={0xbf,0x86,0xdb,0xcf,0xe6,0xed,0xfd,0x87,0xff,0xef};

unsigned char i,j,num,temp;
unsigned int hour,minute,second,tens,units,second1,minute1,hour1;

void delay(unsigned int n)
{
 for(i=n;i>0;i--)
  for(j=0;j<110;j++);
}

void showtime(int x)
{
 tens=x/10;
 units=x%10;
}


void debughour()
{
 if(P3==0xbf)
 {
  delay(1);
  while(P3==0xbf);
  hour++;
  if(hour==24)
   hour=0;
  showtime(hour);
  P0=shows1[tens];
  P2=0x01;
  delay(1);
  P2=0x00;
  P0=shows2[units];
  P2=0x02;
  delay(1);
  P2=0x00;
 }
 if(P3==0xdf)
 {
  delay(1);
  while(P3==0xdf);
  hour--;
  if(hour==-1)
   hour=23;
  showtime(hour);
  P0=shows1[tens];
  P2=0x01;
  delay(1);
  P2=0x00;
  P0=shows2[units];
  P2=0x02;
  delay(1);
  P2=0x00;
 }
 if(P3==0x7f)
 {
  delay(1);
  while(P3==0x7f);
  temp++;
 }
}

void debugminute()
{
 if(P3==0xbf)
 {
  delay(1);
  while(P3==0xbf);
  minute++;
  if(minute==60)
   minute=0;
  showtime(minute);
  P0=shows1[tens];
  P2=0x04;
  delay(1);
  P2=0x00;
  P0=shows2[units];
  P2=0x08;
  delay(1);
  P2=0x00;
 }
 if(P3==0xdf)
 {
  delay(1);
  while(P3==0xdf);
  minute--;
  if(minute==-1)
   minute=59;
  showtime(minute);
  P0=shows1[tens];
  P2=0x04;
  delay(1);
  P2=0x00;
  P0=shows2[units];
  P2=0x08;
  delay(1);
  P2=0x00;
 }
 if(P3==0x7f)
 {
  delay(1);
  while(P3==0x7f);
  temp++;
 }
}
void keyscan1()
{
 while(temp<=2)
 {
  if(P3==0x7f)
  {
   delay(1);
   while(P3==0x7f);
   temp++;
  }
  TR0=0;
  showtime(second);
  P0=shows1[tens];
  P2=0x10;
  delay(1);
  P2=0x00;
  P0=shows1[units];
  P2=0x20;
  delay(1);
  P2=0x00;

  showtime(minute);
  P0=shows1[tens];
  P2=0x04;
  delay(1);
  P2=0x00;
  P0=shows2[units];
  P2=0x08;
  delay(1);
  P2=0x00;

  showtime(hour);
  P0=shows1[tens];
  P2=0x01;
  delay(1);
  P2=0x00;
  P0=shows2[units];
  P2=0x02;
  delay(1);
  P2=0x00;
  if(temp==1)
   debughour();
  if(temp==2)
    debugminute();
  if(temp==3)
  {
   TR0=1;
   temp=0;
   break;
  }
 }
}

 

void keyscan2()
{
 while(temp<=1)
 {
  if(P3==0xef)
  {
   delay(1);
   while(P3==0xef);
   temp++;
  }
  if(num==18)
   {
    num=0;
   P1=~P1;
   second1++;
   if(second1==60)
   {
    second1=0;
    minute1++;
    if(minute1==60)
    {
     minute1=0;
     hour1++;
     if(hour1==100)
      hour1=0;
    }
   }
   second++;
   if(second==60)
   {
    second=0;
    minute++;
    if(minute==60)
    {
     minute=0;
     hour++;
     if(hour==24)
      hour=0;
    }
   }
   }
  showtime(second1);
  P0=shows1[tens];
  P2=0x10;
  delay(1);
  P2=0x00;
  P0=shows1[units];
  P2=0x20;
  delay(1);
  P2=0x00;

  showtime(minute1);
  P0=shows1[tens];
  P2=0x04;
  delay(1);
  P2=0x00;
  P0=shows2[units];
  P2=0x08;
  delay(1);
  P2=0x00;

  showtime(hour1);
  P0=shows1[tens];
  P2=0x01;
  delay(1);
  P2=0x00;
  P0=shows2[units];
  P2=0x02;
  delay(1);
  P2=0x00;
  if(temp==2)
  {
   temp=0;
   hour1=0;
   minute1=0;
   second1=0;
   break;
  }
 } 
}

void runtime()
{
  if(num==18)
  {
   num=0;
  P1=~P1;
  second++;
  if(second==60)
  {
   second=0;
   minute++;
   if(minute==60)
   {
    minute=0;
    hour++;
    if(hour==24)
     hour=0;
   }
  }
  }
}


main()
{
 TMOD=0x01;
 TH0=(65536-50000)/256;
 TL0=(65536-50000)%256;
 EA=1;
 ET0=1;
 TR0=1;
 P3=0xff;
 temp=0;
 hour=3;
 minute=58;
 while(1)
 {
  runtime();
  showtime(second);
  P0=shows1[tens];
  P2=0x10;
  delay(1);
  P2=0x00;
  P0=shows1[units];
  P2=0x20;
  delay(1);
  P2=0x00;

  showtime(minute);
  P0=shows1[tens];
  P2=0x04;
  delay(1);
  P2=0x00;
  P0=shows2[units];
  P2=0x08;
  delay(1);
  P2=0x00;

  showtime(hour);
  P0=shows1[tens];
  P2=0x01;
  delay(1);
  P2=0x00;
  P0=shows2[units];
  P2=0x02;
  delay(1);
  P2=0x00;
  if(P3==0x7f)
   keyscan1();
  if(P3==0xef)
   keyscan2();
 }
}

void timer0() interrupt 1 using 1
{
 TH0=(65536-50000)/256;
 TL0=(65536-50000)%256;
 num++;
}