整个显示分为时、分、秒三部分。时为24时置为0，分为60时置为0并向时进1，秒为60时置为0并向分进1。

程序：

#include
#include
 
 
void delay(unsigned char dly)
{
  unsigned char i,j;
 
  for(i=100;i>0;i--)
    for(j=dly;j>0;j--)
;
}
unsigned char num,time1,time2,time3;
void  timer0()interrupt 1
{
  TH0=(65535-46080)/256;
 
  TL0=(65535-46080)% 256;
  num++;
  if(num==20)
    {
 num=0;
 time1++;
}
}
void intial()
{
   TMOD=0x01;
   ET0=1;
   EA=1;
   TR0=1;
   num=0;
   time1=0;
   time2=0;
   time3=0;
}
void main()
{
  unsigned char table[]={0xC0,0xF9,0xA4,0xB0,0x99,0x92,0x82,0xF8,0x80,0x90};
  unsigned char shi,fen;
  intial();
  while(1)
    {
if(time1==60)
 {
   time1=0;
time2++;
 }
if(time2==60)
  {
     time2=0;
   time3++;
  }
 if(time3==24)
   time3=0;
shi=time1/10;
fen=time1% 10;
P2=0xf7;
P0=table[shi];
delay(2);
P2=0xfb;
P0=table[fen];
delay(2);
shi=time2/10;
fen=time2% 10;
P2=0xdf;
P0=table[shi];
delay(2);
P2=0xef;
P0=table[fen];
delay(2);
shi=time3/10;
fen=time3% 10;
P2=0x7f;
P0=table[shi];
delay(2);
P2=0xbf;
P0=table[fen];
delay(2);
}
}