我所见过的矩阵键盘一般有两种识别方法：扫描法和线反转法。以4X4矩阵键盘为例，扫描法是依次将每一行置为0，然后读取列的状态，这样就可以通过四次扫描将整个矩阵键盘的按键状况辨别出来，这个方法所需的代码量比较长；而线反转法则显得比较简洁，它通过先将4行全部置0（0xf0），然后读列的状态，接着，将列全部置0（0x0f)，读行的状态，通过（行|列）就能确定整个行列的状态了。扫描法比线反转法占用更多的程序储存空间（ProgramSpace),但占用的更少的数据储存空间（Data Space)。
程序如下
扫描法：
#include<reg52.h>
#define uchar unsigned char
#define uint unsigned int
uchar num,c;
uchar codeSSEG[]={0x3f,0x06,0x5b,0x4f,0x66,0x6d,0x7d,0x07,0x7f,0x6f,0x77,0x7c,0x39,0x5e,0x79,0x71};
void delay1ms(uint z)
{
uint x;
uchar y;
for(x=z;x>0;x--)
for(y=110;y>0;y--);
}
void keyscan()
{
uchar temp;
P2=0xfe;
temp=P2&0xf0;
if(temp!=0xf0)
{
delay1ms(10);
temp=P2&0xf0;
if(temp!=0xf0)
{
temp=P2;
switch(temp)
{
case0xee:num=0;break;
case0xde:num=1;break;
case0xbe:num=2;break;
case0x7e:num=3;break;
}
while(temp!=0xf0)//松手检测
{
temp=P2;
temp=temp&0xf0;
}
}
}
P2=0xfd;
temp=P2&0xf0;
if(temp!=0xf0)
{
delay1ms(10);
temp=P2&0xf0;
if(temp!=0xf0)
{
temp=P2;
switch(temp)
{
case0xed:num=4;break;
case0xdd:num=5;break;
case0xbd:num=6;break;
case0x7d:num=7;break;
}
while(temp!=0xf0)
{
temp=P2;
temp=temp&0xf0;
}
}
}
P2=0xfb;
temp=P2&0xf0;
if(temp!=0xf0)
{
delay1ms(10);
temp=P2&0xf0;
if(temp!=0xf0)
{
temp=P2;
switch(temp)
{
case0xeb:num=8;break;
case0xdb:num=9;break;
case0xbb:num=10;break;
case0x7b:num=11;break;
}
while(temp!=0xf0)
{
temp=P2;
temp=temp&0xf0;
}
}
}
P2=0xf7;
temp=P2&0xf0;
if(temp!=0xf0)
{
delay1ms(10);
temp=P2&0xf0;
if(temp!=0xf0)
{
temp=P2;
switch(temp)
{
case0xe7:num=12;break;
case0xd7:num=13;break;
case0xb7:num=14;break;
case0x77:num=15;break;
}
while(temp!=0xf0)
{
temp=P2;
temp=temp&0xf0;
}
}
}
}
void main()
{
num=0xff;
while(1)
{
keyscan();
P1=~SSEG[num];
}
}
线反转法：
#include<reg52.h>
#define uchar unsigned char
#define uint unsigned int
uchar num;
uchar codeSSEG[]={0x3f,0x06,0x5b,0x4f,0x66,0x6d,0x7d,0x07,0x7f,0x6f,0x77,0x7c,0x39,0x5e,0x79,0x71};
void delay1ms(uint z)
{
uint x;
uchar y;
for(x=z;x>0;x--)
for(y=110;y>0;y--);
}
void keyscan()
{
uchar temp,z;
P2=0xf0;
if(P2!=0xf0)
{
delay1ms(10);
if(P2!=0xf0)
{
temp=P2;
P2=0x0f;
z=temp|P2;
temp=P2&0x0f;
while(temp!=0x0f)//松手检测
{
temp=P2&0x0f;
}
switch(z)
{
case0xee: num =0; break;
case 0xde: num =1; break;
case 0xbe: num =2; break;
case 0x7e: num =3; break;
case 0xed: num =4; break;
case 0xdd: num =5; break;
case 0xbd: num =6; break;
case 0x7d: num =7; break;
case 0xeb: num =8; break;
case 0xdb: num =9;break;
case 0xbb: num =10;break;
case 0x7b: num =11;break;
case 0xe7: num =12;break;
case 0xd7: num =13;break;
case 0xb7: num =14;break;
case 0x77: num =15;break;
}
}
}
}
void main()
{
num=0xff;
P2=0xff;
while(1)
{
keyscan();
P1=~SSEG[num];
}
}
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