/*矩陣鍵盤掃描出鍵值，在數(shù)碼管上顯示出來
       P0口接數(shù)碼管的段選碼，P2口通過反相器接數(shù)
       管的位選碼*/
     
       #include<reg52.h>    //所用的器件是AT89S52
       #define uchar unsigned char
     
       void delayms(uchar j);    //聲明延時函數(shù) 
       uchar getkey(void);     //聲明掃描函數(shù)
       void keydisp(uchar k); //聲明顯示函數(shù)
       void disp(uchar l);     //聲明顯示子程序
     
       uchar code table[]={0xc0,0xf9,0xa4,0xb0,0x99,0x92,0x82,
                           0xf8,0x80,0x90,0x88,0x83,0xc6,0xa1,
                           0x86,0x8e};
                             //共陽數(shù)碼管0-F顯示代碼
     
       void main(void)        //主程序
       {
           uchar key;
           while(1)
           {
            key=getkey();
            delayms(20);
            keydisp(key);
           }
       }
     
       void delayms(uchar j)    //延時子程序
       {
        uchar n,m;
        for(n=0;n<j;n++)
        {
         for(m=0;m<120;m++)   //延時時間為1ms
         {;}
        }
       }
     
       uchar getkey(void)      //掃描取鍵值程序
       {
        uchar rcode,ccode;
        P1=0xf0;
        if((P1&0xf0)!=0xf0)
        {
         delayms(20);   //為消除抖動，延時20ms
         if((P1&0xf0)!=0xf0)
         {
          rcode=0xfe;   //開始發(fā)行掃描信號
          while((rcode&0x10)!=0)
          {
         P1=rcode;
           if((P1&0xf0)!=0xf0)
           {
            ccode=(P1&0xf0)|0x0f;
            do{;}while((P1&0xf0)!=0xf0); //當松鍵后顯示
            return((~rcode)+(~ccode));    //返回掃描代碼
           }
           else rcode=(rcode<<1)|0x01; //此行無鍵按下，變化行掃描信號
          }
         }
        }
        return 0;   //無鍵按下，返回0
       }
     
       void keydisp(uchar k)    //顯示程序
       {
        switch(k)
        {
         case 0x11:disp(0);break;
         case 0x21:disp(1);break;
         case 0x41:disp(2);break;
         case 0x81:disp(3);break;
         case 0x12:disp(4);break;
         case 0x22:disp(5);break;
         case 0x42:disp(6);break;
         case 0x82:disp(7);break;
         case 0x14:disp(8);break;
         case 0x24:disp(9);break;
         case 0x44:disp(10);break;
         case 0x84:disp(11);break;
         case 0x18:disp(12);break;
         case 0x28:disp(13);break;
         case 0x48:disp(14);break;
         case 0x88:disp(15);break;
    default:break;
        }
      }
    
      void disp(uchar l) //顯示子程序
      {
       P0=table[l];
       delayms(20);
       P2=0x7f;   //共陽極數(shù)碼管的位選碼
      }