今天在网上看到一种矩阵键盘的线反转法程序，感觉挺好，比之前的扫描法节省了很多，在此分享一下

 uchar key(void)
{
    uchar key,key1,key2,k;
    P1=0XF0;
    k=0xff;
    if((P1&0XF0)!=0XF0)
    {
        delay();
        if((P1&0XF0)!=0XF0)
        key1=P1&0XF0;
        P1=0X0F;
        if((P1&0X0F)!=0X0F)
        {
            delay();
            if((P1&0X0F)!=0X0F)
            {
                key2=P1&0X0F;
                key=key1|key2;
                if(key!=0xff)
                {
                    switch(key)
                    {
                        case 0xee: k=0;break;                       
                        case 0xed: k=1;break;                        
                        case 0xeb: k=2;break;                       
                        case 0xe7: k=3; break;
                        case 0xde: k=4;break;                       
                        case 0xdd: k=5;break;                        
                        case 0xdb: k=6;break;                       
                        case 0xd7: k=7; break;
                         case 0xbe: k=8;break;                       
                        case 0xbd: k=9;break;                        
                        case 0xbb: k=10;break;                       
                        case 0xb7: k=11; break;
                         case 0x7e: k=12;break;                       
                        case 0x7d: k=13;break;                        
                        case 0x7b: k=14;break;                       
                        case 0x77: k=15; break;
                    }
                }
            }
        }
    }
    return(k);
}