#include<reg51.h>
#define uchar unsigned char
#define uint  unsigned int
uchar code led[10]={0xc0,0xF9,0xA4,0xB0,0x99,0x92,0x82,0xF8,0x80,0x90};
uint volt;

sbit CLK=P3^3;
sbit START=P3^0;
sbit EOC=P3^1;
sbit OE=P3^2;

void delay(uint z)        
{ uchar x,y;            
   for(x=z;x>0;x--)   
      for(y=250;y>0;y--);
} 
void ADC()
{
 START=0;
 START=1;
 START=0;
 while(EOC==0);
 OE=1;
 volt=P1;
 OE=0;
 volt=volt*196; 
}
void display()
{
 P0=0XFF;
 P2=0x01;
 P0=led[volt/10000]&0x7F;
 delay(2);
 P0=0XFF;
 P2=0x02;
 P0=led[(volt/1000)%10];
 delay(2);
 P0=0XFF; 
 P2=0x04;
 P0=led[(volt/100)%10];
 delay(2);
 P0=0XFF;  
 P2=0x08;
 P0=led[(volt/10)%10];
 delay(2);
}
void main()
{
 EA=1;
 TMOD=0x02;
 TH0=0XF6;
 TL0=0XF6;
 ET0=1;
 TR0=1;
 while(1)
 {
  ADC();
  display();
 }
}
void timer() interrupt 1
{
 CLK=~CLK;
}