;用p1口與4×4鍵盤相接，橫的是p10、p11、p12、p13，縱的掃描線是p14、p15、p16、p17    
;掃描結果是0,1,2,3,
;          4,5,6,7,
;          8,9,a,b,
;          c,d,e,f
;;本程序出與  浪尖沙博客，http://ily961.blogchina.com
#include<reg51.h>
#include<intrins.h>
#include<absacc.h>

#define	uchar unsigned char



uchar rr;
uchar k;
uchar keydata;




void key_scan(void);          //鍵盤函數定義段；
uchar key_tab(uchar k);
void delay(void);
void key_in(uchar k);

//---------------------------------------------------------------
void main(void)
{
     while(1)
 {
    key_scan();
 }
}//---------------------------------------------------------------------------------------------

void key_scan(void)
{  uchar sccode,recode,i;
        P1=0xf0;
            if((P1&0xf0)!=0xf0)
          {
               delay();
                if((P1&0xf0) !=0xf0)
              {
                        sccode=0xfe;
                    for(i=0;i<4;i++)
                   {
                        P1=sccode;
                     if((P1&0xf0) !=0xf0)
                        {
                              recode=(P1&0xf0)|0x0f;
                              k=(~recode)+(~sccode);
                              rr=P1;

                             key_in(k);
                             break;
                         }
                      else
                         sccode=(sccode<<1)|0x01;
                  }
             }

  }
  //do {ta=P2;}while(ta==rr);
}
void delay()        //去抖動
{int a=2500;
 while(--a);
}

void key_in(uchar k)
{   uchar ta;
    //uchar keydata;

    do {ta=P1;}while(ta==rr);
    keydata=key_tab(k);
}



//-------------------------------------------------------------
uchar key_tab(uchar k)
{ uchar kb;
    switch(k)
{   case 0x11:kb=0x00;break;
    case 0x21:kb=0x01;break;
    case 0x41:kb=0x02;break;
    case 0x81:kb=0x03;break;
    case 0x12:kb=0x04;break;
    case 0x22:kb=0x05;break;
    case 0x42:kb=0x06;break;
    case 0x82:kb=0x07;break;
    case 0x14:kb=0x08;break;
    case 0x24:kb=0x09;break;
    case 0x44:kb=0x0a;break;
    case 0x84:kb=0x0b;break;
    case 0x18:kb=0x0c;break;
    case 0x28:kb=0x0d;break;
    case 0x48:kb=0x0e;break;
    case 0x88:kb=0x0f;break;
    default  :kb=0x00;break;
}
   return kb;
}