#include<reg52.h>
#define uchar unsigned char
#define uint unsigned int
uchar num,temp;
uchar code table[]={
0x3f,0x06,0x5b,0x4f,
0x66,0x6d,0x7d,0x07,
0x7f,0x6f,0x77,0x7c,
0x39,0x5e,0x79,0x71};
sbit dula=P2^6;
sbit wela=P2^7;
void delay(uint z)
{
uint x,y;
for(x=z;x>0;x--)
for(y=110;y>0;y--);
}
void main()
{
dula=1;
P0=0;
dula=0;
wela=1;
P0=0xc0;
wela=0;
while(1)
{
P3=0xfe;
temp=P3;
temp=temp&0xf0;
while(temp!=0xf0)
{
delay(5);
temp=P3;
temp=temp&0xf0;
while(temp!=0xf0)
{
temp=P3;
switch(temp)
{
case 0xee:num=1;break;
case 0xde:num=2;break;
case 0xbe:num=3;break;
case 0x7e:num=4;break;
}
dula=1;
P0=table[num-1];
dula=0;
}
}
}
}
第一个按键按了一下,最后一个while语句是怎么退出这个循环的,temp在最后这个循环里面不是一直都是0xee么?不是不可能退出得了得么= =
|