#include <reg51.h>
#define uchar unsigned char
#define uint unsigned int
uchar buff,times,j;
unsigned char code dispcode[]={0x3f,0x06,0x5b,0x4f, //0,1,2,3
                               0x66,0x6d,0x7d,0x07, //4,5,6,7
                               0x7f,0x6f,0x77,0x7c, //8,9,A,B
                               0x39,0x5e,0x79,0x71,0x00}; //C,D,E,F,null
unsigned char idata value[8];

void delay1ms(void)  //消抖動
{ uchar i;
  for(i=200;i>0;i--);
}

void delay5ms(void)  //延時5ms
{
  unsigned char i,j;
  for(i=5;i>0;i--)
  for(j=248;j>0;j--);
}

void key_scan(void)   //鍵盤輸入掃描函數
{ uchar hang,lie,key;
  P3=0xf0;
  if((P3&0xf0)!=0xf0)   //行碼為0，列碼為1
   { delay1ms();
     if((P3&0xf0)!=0xf0)  //有鍵按下，列碼變為0
      { hang=0xfe;     //逐行掃描
        times++;
              if(times==9)
                times=1;
        while((hang&0x10)!=0)  //掃描完4行后跳出
         { P3=hang;
           if((P3&0xf0)!=0xf0)  //本行有鍵按下
            { lie=(P3&0xf0)|0x0f;
              buff=((~hang)+(~lie));
              switch(buff)
               { case 0x28: key=0;break;
                 case 0x14: key=1;break;
                 case 0x24: key=2;break;
                 case 0x44: key=3;break;
                 case 0x12: key=4;break;
                 case 0x22: key=5;break;
                 case 0x42: key=6;break;
                 case 0x11: key=7;break;
                 case 0x21: key=8;break;
                 case 0x41: key=9;break;
                 case 0x81: key=10;break;
                 case 0x82: key=11;break;
                 case 0x84: key=12;break;
                 case 0x88: key=13;break;
                 case 0x48: key=14;break;
                 case 0x18: key=15;break;
               }
            value[times-1]=key;  //按下的鍵值
            }
           else hang=(hang<<1)|0x01; //下一行掃描

         }
      }
   }
}

void main(void)
{ uchar key;
  while(1)
   { key_scan();
     P0=0;
     for(j=times;j>0;j--) //74LS138掃描