Question

单片机矩形键盘怎么检测?

Answer 1

扫描行或扫描列：
如：
...............
void delay(unsigned int a)
{
unsigned int i,j;
for(i=0;i<a;i++)
for(j=0;j<120;j++);
}
uchar kbscan(void)
{
unsigned char sccode,recode;
P1=0x0f; //发0扫描,列线输入
if ((P2 & 0x0f) != 0x0f) //有键按下
{
delay(20); //延时去抖动
if ((P1&0x0f)!= 0x0f)
{
sccode = 0xef; //逐行扫描初值
while((sccode&0x01)!=0)
{
P1=sccode;
if((P1&0x0f)!=0x0f)
{
recode=(P1&0x0f)|0xf0;
while((P1&0x0f)!=0x0f);//等待键抬起
return((~sccode)+(~recode));
}
else
sccode=(sccode<<1)|0x01;
}
}
}
return 0; //无键按下，返回0
}

uchar getkey(void)
{
unsigned char key,keyval=0xff;
key=kbscan();
switch(key)
{
case 0x11:keyval=1;break;
case 0x12:keyval=2;break;
case 0x14:keyval=3;break;
case 0x18:keyval=10;break; //+
case 0x21:keyval=4;break;
case 0x22:keyval=5;break;
case 0x24:keyval=6;break;
case 0x28:keyval=11;break; //-
case 0x41:keyval=7;break;
case 0x42:keyval=8;break;
case 0x44:keyval=9;break;
case 0x48:keyval=12;break; //清除
case 0x81:keyval=13;break;
case 0x82:keyval=0;break;
case 0x84:keyval=14;break; //小数点
case 0x88:keyval=15;break; //确认
default:keyval=16;break;
}
return(keyval);
}
..................................

Answer 2

矩阵扫描