123

#include <reg51.h>
#define uchar unsigned char
#define uint unsigned int

uchar code table[] = {0xfc,0x60,0xda,0xf2,0x66,0xb6,0xbe,0xe0,0xfe,0xf6,0xee,0x3e,0x9c,0x7a,0x9e,0x8e};

sbit START=P3^0;
sbit EOC=P3^1;
sbit OE=P3^2;
sbit dot=P1^0;

void delay(uint x)
{
    while(x--);
}

void main()
{
    uint temp;
    START=0;
    OE=0;

    START=1;
    START=0;

    while(1)
    {
        if(EOC == 1)
        {
        OE = 1;
        temp=P0;
        temp=temp*1.0/255*500;
        OE = 0;
        P2 = 0xfe;
        P1 = table[temp%10];
        delay(500);
        P2 = 0xfd;
        P1 = table[temp/10%10];
        delay(500);
        P2 = 0xfb;
        P1 = table[temp/100%10];
        dot = 1;
        delay(500);
        START  = 1;
        START  = 0;
        }         
    }
}