51单片机3*4键盘扫描码

51单片机3*4键盘扫描码

这是4*4键盘扫描程序代码：
void delay(uchar a)
{
uchar i,j;
for(i=0;i for(j=0;j<125;j++);
}
uchar kbscan(void)
{
unsigned char sccode,recode;
P3=0x0f; //发0扫描,列线输入
if ((P3 & 0x0f) != 0x0f) //有键按下
{
delay(20); //延时去抖动
if ((P3&0x0f)!= 0x0f)
{
sccode = 0xef; //逐行扫描初值
while((sccode&0x01)!=0)
{
P3=sccode;
if((P3&0x0f)!=0x0f)
{
recode=(P3&0x0f)|0xf0;
while((P3&0x0f)!=0x0f);//等待键抬起
return((~sccode)+(~recode));
}
else
sccode=(sccode<<1)|0x01;
}
}
}
return 0; //无键按下，返回0
}
void getkey(void)
{
unsigned char key;
key=kbscan();
if(key==0)
{
return;
}
switch(key)
{
case 0x11:keyval=7;break;
case 0x12:keyval=4;break;
case 0x14:keyval=1;break;
case 0x18:keyval=10;break;
case 0x21:keyval=8;break;
case 0x22:keyval=5;break;
case 0x24:keyval=2;break;
case 0x28:keyval=0;break;
case 0x41:keyval=9;break;
case 0x42:keyval=6;break;
case 0x44:keyval=3;break;
case 0x48:keyval=11;break;
case 0x81:keyval=12;break;
case 0x82:keyval=13;break;
case 0x84:keyval=14;break;
case 0x88:keyval=15;break;
default:keyval=0xff;break;
}
}