void Key_scan(void)     //確定按鍵子程序
{
uchar key,readkey,x_temp,y_temp;  
P2=0x0f;
x_temp=P2&0x0f;              //確定哪一行按鍵按下
if(x_temp==0x0f) goto keyout;
P2=0xf0;
y_temp=P2&0xf0;             //確定哪一列按鍵按下
readkey=x_temp|y_temp;      //確定具體的按鍵按下

switch(readkey)
    {
case 0xee:key=0;P0=table[key]; break;
case 0xde:key=1;P0=table[key]; break;
case 0xbe:key=2;P0=table[key]; break;
case 0x7e:key=3;P0=table[key]; break;
case 0xed:key=4;P0=table[key]; break;
case 0xdd:key=5;P0=table[key]; break;
case 0xbd:key=6;P0=table[key]; break;
case 0x7d:key=7;P0=table[key]; break;
case 0xeb:key=8;P0=table[key]; break;
case 0xdb:key=9;P0=table[key]; break;
case 0xbb:key=10;P0=table[key];break;
case 0x7b:key=11;P0=table[key];break;
case 0xe7:key=12;P0=table[key];break;
case 0xd7:key=13;P0=table[key];break;
case 0xb7:key=14;P0=table[key];break;
case 0x77:key=15;P0=table[key];break;
default:break;
    }

keyout:_nop_();
}