//鍵盤掃描處理,無按鍵返回0,有按鍵返回鍵值,鍵值對(duì)應(yīng)于keycode[]下標(biāo)值。8條(以P2為例）口線24按鍵
//鍵盤碼也可定義為局部數(shù)組變量
unsigned char code keycode[]=
{0x00,0xee,0xde,0xbe,0xed,0xdd,0xbd,0xeb,0xdb,0xbb,0xd7,0xe7,0xb7,0x7b,0x7d,0x7e,0x77,

0xfe,0xfd,0xfb,0xf7,0xef,0xdf,0x7f,0xbf};

unsigned char keyread(void)
{ unsigned char i,j,x,k1,k2;
P2=0xff;
if(P2!=0xff)
{k1=P2;
delay();
P2=0xff;
if(P2!=0xff)
{for(P2=0xff;P2!=0xff;P2=0xff)
x=k1;}
}
else{x=0;
}
//以上判斷接地按鍵
//以下判斷交叉按鍵(反轉(zhuǎn)法）
if(x==0)
{P2=0x0f;
if(P2!=0x0f)
{delay();
P2=0x0f;
if(P2!=0x0f)
{k1=P2;
P2=0xf0;
if(P2!=0xf0)
{k2=P2;
for(P2=0xf0;P2!=0xf0;P2=0xf0)
x=k1^k2;}
}
}
else{x=0;} }
if(x==0){i=0;}
else{i=j=0xff;
do{i++;j++;
if(keycode[i]==x){j=24;}
else if(j==24){i=0;}else{;} }

while(j!=24);}

return(i);
}

void delay()//延時(shí)
{ unsigned char b;
for (b=0;b<=0xff;b++)
{
for (b=0;b<=0xff;b++)
{;}
}
}