用单片机p2口扩展一个4*4键盘，用c语言实现按键识别程序

Question

如题所述

Answer 1

#include<reg51.h>
#define uchar unsigned char;
uchar keyval;
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;
P2=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 ((P2&0x0f)!= 0x0f)
{
sccode = 0xef; //逐行扫描初值
while((sccode&0x01)!=0)
{
P2=sccode;
if((P2&0x0f)!=0x0f)
{
recode=(P2&0x0f)|0xf0;
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){keyval=0xff;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;
}
}

main()
{
while(1)
{
getkey();
switch(keyval)
{
case 0:
case 1:
case 2:
case 3:
case 4:
case 5:
case 6:
case 7:
case 8:
case 9:
case 10:
case 11:
case 12:
case 13:
case 14:
case 15:
default:break;
}
}
}

Answer 2

#include<reg52.h>
#define uchar unsigned char
#define uint unsigned int
sbit dula=P2^6;
sbit wela=P2^7;
uchar code table[]={
0x3f,0x06,0x5b,0x4f,
0x66,0x6d,0x7d,0x07,
0x7f,0x6f,0x77,0x7c,
0x39,0x5e,0x79,0x71,0x67};
void delay(uint m)
{ uint i,j;
for(i=m;i>0;i--)
for(j=110;j>0;j--);
}
void display(uchar num)
{ wela=1;
P0=0xc0;
wela=0;
P0=0XFF;
dula=1;
P0=table[num];
dula=0;
}
void keycans()
{ uchar a,key,c;
P3=0X0f;
if(P3!=0X0f)
{ delay(10);
if(P3!=0x0f)
{
a=P3;
P3=0Xf0;
c=P3;
a=a|c;
switch(a)
{case 0xee:key=1;break;
case 0xde:key=2;break;
case 0xbe:key=3;break;
case 0x7e:key=4;break;
case 0xed:key=5;break;
case 0xdd:key=6;break;
case 0xbd:key=7;break;
case 0x7d:key=8;break;
case 0xeb:key=9;break;
case 0xdb:key=10;break;
case 0xbb:key=11;break;
case 0x7b:key=12;break;
case 0xe7:key=13;break;
case 0xd7:key=14;break;
case 0xb7:key=15;break;
case 0x77:key=16;break;

}
while(!a);
display(key);
}
}
}
void main()
{
while(1)
keycans();
}