#include <reg51.h>
#define uchar unsigned char
#define uint unsigned int
sbit P3_5=P3^5;
sbit P3_4=P3^4;
sbit P3_3=P3^3;
sbit P2_7=P2^7;
char bdata a;
sbit a_0=a^0;
uchar code tab[16]={0x3F,0x06,0x5B,0x4F,0x66,0x6D,0x7D,0x07,0x7F,0x6F,0x77,0x7C,0x39,0x5E,0x79,0x71};
void read(void)
{
  uchar i;
  a<<=1;
  a_0=(a_0 | P3_5);
  for (i=7;i;i--)
   {
       P3_4=1;
       i=i; i=i;
       P3_4=0;
       i=i; i=i;
       a<<=1;
       a_0=a_0 | P3_5;
   }
   P3_4=1;
   i=i;i=i;
   P3_4=0;
   i=i;i=i;
   
}

void delay(void)
{
   uchar j;
   for(j=0;j<13;j++);
}
 

void display(uchar a)
{
   uchar r2;
   uint j;
   P1=0;
   r2=a;
   a=a&0xf0;
   a>>=4;
   P2=0x80|tab[a];				/*p2.7=1,禁止蜂鳴器發聲 */
   P1=0x01;
   for(j=0;j<=2500;j++);		/*延時*/
   a=r2;
   a=a&0x0f;
   P2=0x80|tab[a];				/*p2.7=1,禁止蜂鳴器發聲 */
   P1<<=1;
   for(j=0;j<=2500;j++);		/*延時*/
}

main()
{  
   P2_7=1;  
    while(1)
  {
   a=0;
   P3_5=1;
   P3_3=1;
   P3_4=0;
   P3_3=0;
   read();
   P3_3=1;
   delay();
   P3_3=0;
   read();
   P3_3=1;
   display(a);
   }
}