本代码利用定时器2产生中断,并在中断里面对temp++,然后通过数码管将temp的值显示出来.代码如下: 
#include<mega16.h>
#include<delay.h>
#define uchar unsigned char
#define uint unsigned int
long temp;
unsigned char t;
 
interrupt [TIM2_OVF] void time0_out(void)
{
    TCNT2=0x00;
    t++;
    if(t>250){t=0;temp++;}
}       
//digital number display function, the first parameter is the number you want to show
//the second parameter is the position of the number
void display(unsigned char number,unsigned char position);
void main(void)
{
    unsigned char b1,b2,b3,b4,b5,b6,b7,b8;
 
 TCCR2=0X03;//64c
 TCNT2=0X00;
 TIMSK=0X40;
 #asm("sei") //open all interrupt
 
 while(1)
 {
   b1=temp%10;display(b1,8);delay_us(500);
   b2=(temp/10)%10;display(b2,7);delay_us(500);
   b3=(temp/100)%10;display(b3,6);delay_us(500);
   b4=(temp/1000)%10;display(b4,5);delay_us(500);
   b5=(temp/10000)%10;display(b5,4);delay_us(500);
   b6=(temp/100000)%10;display(b6,3);delay_us(500);
   b7=(temp/1000000)%10;display(b7,2);delay_us(500);
    b8=(temp/10000000)%10;display(b8,1);delay_us(500);
    if(temp>99999999)temp=0;
    }
}
void display(unsigned char number,unsigned char position)//digtial show function
{  
    DDRA=0Xff;//set PORTA output
 PORTA=0XFF;//set PORTA output in high level
    switch(position)//choice the position
 {
  case 1:{PORTA&=0xf8;break;}
  case 2:{PORTA&=0xf9;break;}
  case 3:{PORTA&=0Xfa;break;}
  case 4:{PORTA&=0Xfb;break;}
  case 5:{PORTA&=0Xfc;break;}
  case 6:{PORTA&=0Xfd;break;}
  case 7:{PORTA&=0Xfe;break;}
  case 8:{PORTA&=0Xff;break;}
  } 
    switch(number)//show number
 {
  case 0:{PORTA&=0x87;break;}    //0
  case 1:{PORTA&=0x8f;break;}    //1
  case 2:{PORTA&=0x97;break;}    //2
  case 3:{PORTA&=0x9f;break;}    //3
  case 4:{PORTA&=0xa7;break;}    //4
     case 5:{PORTA&=0xaf;break;}    //5
  case 6:{PORTA&=0xb7;break;}    //6
  case 7:{PORTA&=0xbf;break;}    //7
  case 8:{PORTA&=0xc7;break;}    //8
     case 9:{PORTA&=0xcf;break;}    //9
  default:{PORTA=0xff;break;}    //null
 }       
}