#include<reg52.h>
#include<intrins.h>
#define uint unsigned int
#define uchar unsigned char
uchar temp,aa,bai,shi,ge;
sbit dula=P2^6;
sbit wela=P2^7;
uchar code table[]={
0x3f,0x06,0x5b,0x4f,
0x66,0x6d,0x7d,0x07,
0x7f,0x6f,0x77,0x7c,
0x39,0x5e,0x79,0x71};
void display(uchar bai,uchar shi,uchar ge);
void delay(uint z);
void init();

void main()
{
init();//初始化程序
while(1)
{
if(aa==20)
{
aa=0;
temp++;
if(temp==100)
{
temp=0;
}
bai=temp/100;
shi=temp%100/10;
ge=temp%10;

}
display(bai,shi,ge);
}
}

void delay(uint z)
{
uint x,y;
for(x=z;x>0;x--)
for(y=110;y>0;y--);
}

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

}
void init()
{
wela=0;
dula=0;
temp=0;
TMOD=0x01;
TH0=(65536-50000)/256;
TL0=(65536-50000)%256;
EA=1;
ET0=1;
TR0=1;
}
void display(uchar bai,uchar shi,uchar ge)
{
dula=1;
P0=table[bai];
dula=0;
P0=0xff; //消影
wela=1;
P0=0xfe;
wela=0;
delay(5);

dula=1;
P0=table[shi];
dula=0;
P0=0xff;
wela=1;
P0=0xfd;
wela=0;
delay(5);

dula=1;
P0=table[ge];
dula=0;
P0=0xff;
wela=1;
P0=0xfb;
wela=0;
delay(5);

}

数码管显示从1开始计数三位（51单片机）