#include   //包含crol移位子函数的头文件

#define uchar unsigned char

#defind uint  unsigned int

uchar key_value=0x19;

uchar temp,a;

uchar keyboard()

{     

       uchari,t=4;

       P2=0xFF;                     //P2口写1

       a=0x7F;//p_value赋初始值 

       i=1;

       while(t--)

       {                                               

              a=_crol_(a,1);//循环左移一位，检测下一行

              key_scan();                   

              i++;

              if(i==5){ i=1; a=0x7f;}              

       }

       returnkey_value;

}

void key_scan()

{     

              P2=a;                                                  //P2.0置零

              temp=P2;                                  //读P2口的值

              temp=temp&0xF0;               //取高四位,都得用temp，即temp=p2,temp=temp&0xf0;

              while(temp!=0xF0)       //如果高四位不全为0，则有键下

              {

                     delay(5);                             //延时消抖

                     while(temp!=0xF0) //再读一次，如果高四位还是不全为0，真的有键按下了

                     {

                                   temp=P2;              //读P2口的值给temp

                                   switch(temp)

                                   {                                        

                                          case0xEE:key_value=0;       break;

                                          case0xDE:key_value=1;  break;

                                          case0xBE:key_value=2;  break;

                                          case0x7E:key_value=3;  break;

                                          case0xED:key_value=4;  break;

                                          case0xDD:key_value=5;  break;

                                          case0xBD:key_value=6;  break;

                                          case0x7D:key_value=7;  break;

                                          case0xEB:key_value=8;  break;

                                          case0xDB:key_value=9;  break;

                                          case0xBB:key_value=10; break;

                                          case0x7B:key_value=11; break;

                                          case0xE7:key_value=12; break;

                                          case0xD7:key_value=13; break;

                                          case0xB7:key_value=14; break;

                                          case0x77:key_value=15; break;

                                   }                                 

                                   while(temp!=0xf0)               //松手检测

                                   {                          

                                          temp=P2;

                                          temp=temp&0xf0;

                                   }

                     }

              }                   

}

void delay(uint z)

{

       uintm,n;

       for(m=z;m>0;m--)

              for(n=78;n>0;n--);

}​