51单片机按键扫描程序

#include
#define uint unsigned int
#define uchar unsigned char
void delay(uint z);
sbit LE=P1^4;
uchar code table[]={
0xfc,0x60,0xda,0xf2,
0x66,0xb6,0xbe,0xe0,
0xfe,0xf6,0xee,0x3e,
0x9c,0x7a,0x9e,0x8e
};
void main()
{
uchar temp;
uint num;
while(1)
{
P2=0xfe; //按键扫描第一行
temp=P2;
temp=temp&0xf0;
while(temp!=0xf0)
{
delay(10); //消抖
temp=P2;
temp=temp&0xf0;
while(temp!=0xf0) //再次确认是否有键按下
{
temp=P2;
switch(temp)
{
case 0xee:num=0;break;
case 0xde:num=1;break;
case 0xbe:num=2;break;
case 0x7e:num=3;break;
}
while(temp!=0xf0) //松手检测
{
temp=P2;
temp=temp&0xf0;
}
delay(10); //消抖
LE=1;
P0=table[num];
LE=0;
P1=0x0f;
}
}


P2=0xfd; //按键扫描第二行
temp=P2;
temp=temp&0xf0;
while(temp!=0xf0)
{
delay(10);
temp=P2;
temp=temp&0xf0;
while(temp!=0xf0)
{
temp=P2;
switch(temp)
{
case 0xed:num=4;break;
case 0xdd:num=5;break;
case 0xbd:num=6;break;
case 0x7d:num=7;break;
}
while(temp!=0xf0)
{
temp=P2;
temp=temp&0xf0;
}
delay(10);
LE=1;
P0=table[num];
LE=0;
P1=0x0f;
}
}


P2=0xfb; //按键扫描第三行
temp=P2;
temp=temp&0xf0;
while(temp!=0xf0)
{
delay(10);
temp=P2;
temp=temp&0xf0;
while(temp!=0xf0)
{
temp=P2;
switch(temp)
{
case 0xeb:num=8;break;
case 0xdb:num=9;break;
case 0xbb:num=10;break;
case 0x7b:num=11;break;
}
while(temp!=0xf0)
{
temp=P2;
temp=temp&0xf0;
}
delay(10);
LE=1;
P0=table[num];
LE=0;
P1=0x0f;
}
}


P2=0xf7; //按键扫描第四行
temp=P2;
temp=temp&0xf0;
while(temp!=0xf0)
{
delay(10);
temp=P2;
temp=temp&0xf0;
while(temp!=0xf0)
{
temp=P2;
switch(temp)
{
case 0xe7:num=12;break;
case 0xd7:num=13;break;
case 0xb7:num=14;break;
case 0x77:num=15;break;
}
while(temp!=0xf0)
{
temp=P2;
temp=temp&0xf0;
}
delay(10);
LE=1;
P0=table[num];
LE=0;
P1=0x0f;
}
}
}
}

void delay(uint z) //延时子函数
{
uint x;
for(z;z>0;z--)
for(x=1000;x>0;x--);
}