单片机键盘的操作 -

键盘的应用和分类：

本文引用地址: http://www.21ic.com/app/mcu/201809/783053.htm

键盘分为编码键盘和非编码键盘，键盘上闭合键的识别是由专门的硬件编码器实现，并产生键编码号或者是键值的成为编码键盘，如计算机的键盘

靠软件编程来识别的称为非编码键盘；

在单片机组成的各种系统中，用的最多的是非编码键盘，也有用到编码键盘的

非编码键盘又有独立键盘和矩阵键盘。

要先像键盘里面先写1；在读取操作

示例代码：

#include

#define uint unsigned int

#define uchar unsigned char

sbit ld1 = P1^0;

sbit key1 = P3^4;

sbit dula = P2^6;

sbit wela = P2^7;

uchar num;

uchar code table[]={0x3f,0x06,0x5b,0x4f,

0x66,0x6d,0x7d,0x07,

0x7f,0x6f,0x77,0x7c,

0x39,0x5e,0x79,0x71};

void display(num);

main()

{

P3 = 0xff;

while(1)

{

display(num);

if(key1==0)

{

ld1 = 0;

num++;

if(num==10)

num = 0;

while(key1!=1);//松手检测

}

else

ld1 = 1;

}

}

void display(num)

{

wela = 1;

P0 = 0xfe;

wela = 0;

P0 = 0x0;

dula = 1;

P0 = table[num];

dula = 0;

dula = 1;//关灯操作

P0 = 0x0;

dula = 0;

}

View Code

这个程序看上去无懈可击，但是在实际过程中，有一个相当大打bug，那就是，你按住键盘的时候，数码管不显示数字，这不是很坑爹，所以，位选信号是开始就要打开的正确的代码是

#include

#define uint unsigned int

#define uchar unsigned char

sbit ld1 = P1^0;

sbit key1 = P3^4;

sbit dula = P2^6;

sbit wela = P2^7;

uchar num;

uchar code table[]={0x3f,0x06,0x5b,0x4f,

0x66,0x6d,0x7d,0x07,

0x7f,0x6f,0x77,0x7c,

0x39,0x5e,0x79,0x71};

void display(num);

main()

{

P3 = 0xff;

wela = 1;

P0 = 0xfe;//打开位选线

wela = 0;

while(1)

{

if(key1==0)

{

ld1 = 0;

num++;

if(num==10)

num = 0;

while(key1!=1);//松手检测

}

else

ld1 = 1;

dula = 1;

P0 = table[num];//在循环中不断送入段选

dula = 0;

}

}

去抖：由于按键接触的时候会出现抖动，所以，要进行去抖操作

去抖有硬件消抖和软件消抖

硬件消抖要用专门的硬件消抖电路，导致外部电路复杂，在单片机中用不着

软件消抖，一般是延时5毫秒检测

#include

#define uint unsigned int

#define uchar unsigned char

sbit ld1 = P1^0;

sbit key1 = P3^4;

sbit dula = P2^6;

sbit wela = P2^7;

uchar num;

uchar code table[]={0x3f,0x06,0x5b,0x4f,

0x66,0x6d,0x7d,0x07,

0x7f,0x6f,0x77,0x7c,

0x39,0x5e,0x79,0x71};

void delay(uint x);

main()

{

P3 = 0xff;

wela = 1;

P0 = 0xfe;//打开位选线

wela = 0;

while(1)

{

if(key1==0)

{

delay(10);//延时十毫秒

if(key1 == 0)//确实按下去了

{

ld1 = 0;

num++;

if(num==10)

num = 0;

while(key1!=1);//松手检测

delay(10); //检测是否松手

while(!key1);

}

}

else

ld1 = 1;

dula = 1;

P0 = table[num];//在循环中不断送入段选

dula = 0;

}

}

void delay(uint x)

{

uint y,z;

for(y=x;y>0;y--)

for(z=110;z>0;z--);

}

矩阵键盘：无论是矩阵键盘还是独立键盘，单片机检测其是否被按下去的依据都是一样的，也就是检测该键盘对应的I/O口是否为低电平，独立键盘有一段固定是低电平，单片机写程序时检测比较方便，电路时矩阵键盘的两端都与单片机deI/O口相连，因此在检测时，先送入一列为低电平，其余的全部为高电平，此时我们确定了列数，然后立即轮流检测一次各行是否有低电平，检测到某一行为低电平（这是我们有确定了行数），着我们便可确定是哪一行哪一列的按键被按下去。

示例代码：

#include

sbit wela =P2^6;

sbit dula = P2^7;

#define uchar unsigned char

#define uint unsigned int

void delay(uint z);

uchar num,num1,temp;

uchar keyscan();

uchar code table[]={0x3f,0x06,0x5b,0x4f,

0x66,0x6d,0x7d,0x07,

0x7f,0x6f,0x77,0x7c,

0x39,0x5e,0x79,0x71,0x0};

main()

{

wela = 1;

P0 = 0x0;

wela = 0;

while(1)

{

num1 = keyscan();

dula =1;

P0 = table[num1];

dula = 0;

}

}

void delay(uint z)

{

uint x,y;

for(x=z;x>0;x--)

for(y=110;y>0;y--);

}

uchar keyscan()

{

P3 = 0xfe;//1111 1110

temp = P3;

temp = temp&0xf0;//11110000

while(temp!=0xf0)//如果有键摁下

{

delay(5);//再次检测P3口

temp = P3;

temp = temp&0xf0;

while(temp!=0xf0)

{

temp = P3;

switch(temp)

{

case 0x7e:num = 1;

break;

case 0xbe:num = 2;

break;

case 0xde:num = 3;

break;

case 0xee:num = 4;

break;

}

while(temp!=0xf0)//松手检测

{

temp = P3;

temp = temp&0xf0;

}

}

}

P3 = 0xfd;//1111 1101

temp = P3;

temp = temp&0xf0;//11110000

while(temp!=0xf0)//如果有键摁下