矩阵键盘检测子程序【常规法和线反转法】

/*常规法*/

/*常规法*/
uchar keyscan()
{
P1=0xfe;
temp=P1;
temp=temp&0xf0;
while(temp!=0xf0)
{
delay(5);
temp=P1;
temp=temp&0xf0;
while(temp!=0xf0)
{
temp=P1;
switch(temp)
{
case 0xee:num=1;
break;
case 0xde:num=2;
break;
case 0xbe:num=3;
break;
case 0x7e:num=4;
break;
}
while(temp!=0xf0)
{
temp=P1;
temp=temp&0xf0;
}
}
}

P1=0xfd;
temp=P1;
temp=temp&0xf0;
while(temp!=0xf0)
{
delay(5);
temp=P1;
temp=temp&0xf0;
while(temp!=0xf0)
{
temp=P1;
switch(temp)
{
case 0xed:num=5;
break;
case 0xdd:num=6;
break;
case 0xbd:num=7;
break;
case 0x7d:num=8;
break;
}
while(temp!=0xf0)
{
temp=P1;
temp=temp&0xf0;
}
}
}

P1=0xfb;
temp=P1;
temp=temp&0xf0;
while(temp!=0xf0)
{
delay(5);
temp=P1;
temp=temp&0xf0;
while(temp!=0xf0)
{
temp=P1;
switch(temp)
{
case 0xeb:num=9;
break;
case 0xdb:num=10;
break;
case 0xbb:num=11;
break;
case 0x7b:num=12;
break;
}
while(temp!=0xf0)
{
temp=P1;
temp=temp&0xf0;
}
}
}

P1=0xf7;
temp=P1;
temp=temp&0xf0;
while(temp!=0xf0)
{
delay(5);
temp=P1;
temp=temp&0xf0;
while(temp!=0xf0)
{
temp=P1;
switch(temp)
{
case 0xe7:num=13;
break;
case 0xd7:num=14;
break;
case 0xb7:num=15;
break;
case 0x77:num=16;
break;
}
while(temp!=0xf0)
{
temp=P1;
temp=temp&0xf0;
}
}
}
return num;

}

/**********************************************************

线反转法

**********************************************************/
uchar  keyscan()
{
uchar  scan1,scan2,keycode,j;

P1=0xf0;
scan1=P1;
if((scan1&0xf0)!=0xf0)          //判键是否按下
{
   delay1ms(20);                //延时20ms
   scan1=P1;
   if((scan1&0xf0)!=0xf0)       //二次判键是否按下
   {
      P1=0x0f;  //线反转法的核心
      scan2=P1;
      keycode=scan1|scan2;       //组合成键编码

      for(j=0;j<=15;j++)
      {
         if(keycode== key_code[j])  //查表得键值
         {
            key=j;
            return(key);
         }
      }
   }
}
else
P1=0xff; //P1口写1 输入状态
return (16);//"-"
}