本程序在一位上顯示按鍵，如果多位顯示主程序需要修高為多位顯示。本程序軟件包括去抖功能，沒有注釋說明。
#include<reg51.h>
#define uchar unsigned char
#define uint  unsigned int 
uint key,i;
uchar temp,temp1,ms,buff;
uchar tab[]={0xc0,0xf9,0xa4,0xb0,0x99,0x92,0x82,0xf8,0x80,
             0x90,0x88,0x83,0xc6,0xa1,0x86,0x8e};
void delay(ms)
{
 while(ms--)
  {
   for(i=0;i<120;i++);
  }
}
void B_key()
{  
  temp1=0xfe;
  P1=temp1;
  if(P1!=temp1)
      {
     delay(10);
     if (P1!=temp1)
        {
          temp=P1;
          switch(temp)
            {
           case 0xee:key=0;break;
           case 0xde:key=1;break;
           case 0xbe:key=2;break;
           case 0x7e:key=3;break;
           default:break;
            }
        }
       } 
  temp1=0xfd;
  P1=temp1;
  if(P1!=temp1)
      {
     delay(10);
     if (P1!=temp1)
        {
          temp=P1;
          switch(temp)
            {
           case 0xed:key=4;break;
           case 0xdd:key=5;break;
           case 0xbd:key=6;break;
           case 0x7d:key=7;break;
           default:break;
            }
           }
       }
   temp1=0xfb;
   P1=temp1;
  if(P1!=temp1)
     {
        delay(10);
     if (P1!=temp1)
        {
         temp=P1;
         switch(temp)
            {
           case 0xeb:key=8;break;
           case 0xdb:key=9;break;
           case 0xbb:key=10;break;
           case 0x7b:key=11;break;
           default:break;
            }
        }
     }
   temp1=0xf7;
   P1=temp1;
  if(P1!=temp1)
      {
     delay(10);
     if (P1!=temp1)
        {
          temp=P1;
          switch(temp)
            {
           case 0xe7:key=12;break;
           case 0xd7:key=13;break;
           case 0xb7:key=14;break;
           case 0x77:key=15;break;
           default:break;
           }
        }
    }   
}
void main()
{
while(1)
 {
     B_key();
  P2=tab[key];
  P3=0x04;
 }
}