原创 4*4行列式键盘扫描程序

uchar code keytab[]={0x7E,0x7D,0x7B,0x77,  //0,1,2,3,
                     0xBE,0xBD,0xBB,0xB7,   //4,5,6,7,
                     0xDE,0xDD,0xDB,0xD7,   //8,9,a,b,
                     0xEE,0xED,0xEB,0xE7};  //c,d,e,f,

uchar KeyScan()
{
 uint i;
 uchar h="0xef",b,c;
 for(i=4,P1=h;i>0;i--)
 {
  if((P1&0x0f)!=0x0f)
  {
   Delay(5000);
   if((P1&0x0f)!=0x0f)
   {
    uchar key,p;
    p=P1;
    for(key=0;key<16;key++)
    {
     if(p==keytab[key])
     {
      do{
       _nop_();
      }while((P1&0x0f)==0x0f); //等待按键放开，很重要
      //P1=0xff;
      return(key);
     }
    }
   }
   
  }
  b=h>>7;          
  c=h<<1;
  h=c|b;                 
  P1=h;
 }
 P1=0xff;
 return(16);
}