原理图
按键抖动
按键抖动必然存在，一般在10ms左右，采用定时器定期扫描，连续16ms按键状态一致，可以判定按键按下或者抬起状态。
单按键扫描
按键控制数码管显示，按一次，显示数字加一，0到9循环往复，代码：
#include <reg52.h>
sbit ADDR0 = P1^0;
sbit ADDR1 = P1^1;
sbit ADDR2 = P1^2;
sbit ADDR3 = P1^3;
sbit ENLED = P1^4;
sbit KEY1 = P2^4;
sbit KEY2 = P2^5;
sbit KEY3 = P2^6;
sbit KEY4 = P2^7;
unsigned char code LedChar[] = { //数码管显示字符转换表
0xC0, 0xF9, 0xA4, 0xB0, 0x99, 0x92, 0x82, 0xF8,
0x80, 0x90, 0x88, 0x83, 0xC6, 0xA1, 0x86, 0x8E
};
bit KeySta = 1; //当前按键状态,初始状态是高电平，即按键抬起
unsigned char THR0,TLR0;
void ConfigTimer(unsigned long ms);
void main()
{
unsigned char cnt = 0; //保存按键按下次数，显示在数码管上
bit backup = 1; //用于保留上一次按键状态，初始值为1，按键抬起；
ENLED = 0;
ADDR3 = 1;
ADDR2 = 0;
ADDR1 = 0;
ADDR0 = 0;
ConfigTimer(1); //计算定时1ms，需要赋的初值，存在在 THR0,TLR0中
TMOD = TMOD & 0xF0;
TMOD = TMOD | 0x01; //设置定时器模式1 ,不影响高四位
TH0 = THR0; //定时器赋初值
TL0 = TLR0;
EA = 1; //使能总中断
ET0= 1; //使能T0中断
TR0 = 1; //启动定时器T0
P2 = 0xF7; //P2.3 置 0，即 KeyOut1 输出低电平
P0 = LedChar[cnt]; //显示按键次数初值
while(1)
{
if(KeySta != backup) //当前按键状态和上次按键状态不一致，有按键动作发生
{
if(KeySta == 0) //如果当前为0，说明为按下动作
{
cnt++;
if(cnt==10)
cnt = 0;
P0 = LedChar[cnt];
}
backup = KeySta; //更新上一次按键状态
}
}
}
void ConfigTimer(unsigned long ms)
{
unsigned long temp;
temp = 65536 - ms*11059200/1000/12; //ms最大定时71ms
THR0 = (unsigned char)(temp>>8); //取计数值高八位 ，计数值不会超过65535，最多占用16位。
TLR0 = (char)temp; //取计数值低八位
}
void InterruptTimer0() interrupt 1 //每间隔1ms，点亮点整中的某一排，循环往复不停歇
{
static unsigned char keybuf = 0xff; //按键状态保存区
TH0 = THR0; //定时器赋初值
TL0 = TLR0;
keybuf = (keybuf<<1)|KEY4;
if(keybuf == 0x00)
{
KeySta = 0; //按键已经按下
}
else if(keybuf == 0xff)
{
KeySta = 1; //按键已经抬起
}
else //其他杂乱状态，保留原来按键状态，不更新
{}
}
矩阵按键
每1ms扫描一行按键，4ms扫描完所有按键。如果4次扫描状态一致，可以确定按键状态（也就是12ms内状态一致）。
功能：一共4行4列，16个按键，按下对应按键，显示对应数字。
代码：
#include <reg52.h>
sbit ADDR0 = P1^0;
sbit ADDR1 = P1^1;
sbit ADDR2 = P1^2;
sbit ADDR3 = P1^3;
sbit ENLED = P1^4;
sbit KEY_IN_1 = P2^4;
sbit KEY_IN_2 = P2^5;
sbit KEY_IN_3 = P2^6;
sbit KEY_IN_4 = P2^7;
sbit KEY_OUT_1 = P2^3;
sbit KEY_OUT_2 = P2^2;
sbit KEY_OUT_3 = P2^1;
sbit KEY_OUT_4 = P2^0;
unsigned char code LedChar[] = { //数码管显示字符转换表
0xC0, 0xF9, 0xA4, 0xB0, 0x99, 0x92, 0x82, 0xF8,
0x80, 0x90, 0x88, 0x83, 0xC6, 0xA1, 0x86, 0x8E
};
unsigned char KeySta[4][4] = { //全部矩阵按键的当前状态
{1, 1, 1, 1}, {1, 1, 1, 1}, {1, 1, 1, 1}, {1, 1, 1, 1}
};
unsigned char THR0,TLR0;
void ConfigTimer(unsigned long ms);
void main()
{
unsigned char i,j;
unsigned char backup[4][4]={
{1,1,1,1}, {1,1,1,1},{1,1,1,1},{1,1,1,1}
};
ENLED = 0;
ADDR3 = 1;
ADDR2 = 0;
ADDR1 = 0;
ADDR0 = 0;
ConfigTimer(1); //计算定时1ms，需要赋的初值，存在在 THR0,TLR0中
TMOD = TMOD & 0xF0;
TMOD = TMOD | 0x01; //设置定时器模式1 ,不影响高四位
TH0 = THR0; //定时器赋初值
TL0 = TLR0;
EA = 1; //使能总中断
ET0= 1; //使能T0中断
TR0 = 1; //启动定时器T0
P0 = LedChar[0]; //数码管默认显示0
while(1)
{
for(i=0;i<4;i++)
{
for(j=0;j<4;j++)
{
if(KeySta[i][j]!=backup[i][j]) //当前按键状态和之前按键状态不一致，证明按键已经按下或者抬起
{
if(KeySta[i][j]==0) //如果当前按键状态为0，说明按键按下；在此我们只对按键按下动作响应
{
P0 = LedChar[i*4+j];
}
backup[i][j]=KeySta[i][j]; //保存当前按键状态
}
}
}
}
}
void ConfigTimer(unsigned long ms)
{
unsigned long temp;
temp = 65536 - ms*11059200/1000/12; //ms最大定时71ms
THR0 = (unsigned char)(temp>>8); //取计数值高八位 ，计数值不会超过65535，最多占用16位。
TLR0 = (char)temp; //取计数值低八位
}
void InterruptTimer0() interrupt 1
{
static unsigned char keyout = 0;
unsigned char i;
static unsigned char keybuf[4][4]={
{0xff,0xff,0xff,0xff},{0xff,0xff,0xff,0xff},{0xff,0xff,0xff,0xff},{0xff,0xff,0xff,0xff}
};
TH0 = THR0;
TL0 = TLR0;
keybuf[keyout][0] = (keybuf[keyout][0]<<1)| KEY_IN_1;
keybuf[keyout][1] = (keybuf[keyout][1]<<1)| KEY_IN_2;
keybuf[keyout][2] = (keybuf[keyout][2]<<1)| KEY_IN_3;
keybuf[keyout][3] = (keybuf[keyout][3]<<1)| KEY_IN_4;
for(i=0;i<=3;i++)
{
if((keybuf[keyout][i]&0x0f)==0x00)
{
KeySta[keyout][i]=0;
}
else if((keybuf[keyout][i]&0x0f)==0x0f)
{
KeySta[keyout][i]=1;
}
else
{}
}
keyout++;
if(keyout>=4)
{keyout=0;}
switch(keyout) //扫描下一行
{
case 0: KEY_OUT_4=1;KEY_OUT_1=0;break;
case 1: KEY_OUT_1=1;KEY_OUT_2=0;break;
case 2: KEY_OUT_2=1;KEY_OUT_3=0;break;
case 3: KEY_OUT_3=1;KEY_OUT_4=0;break;
default:break;
}
}
简易加法器：
说明：按键显示对应数字在数码管；按键上代替加号，按键按键代替加号，Esc按键清零。
代码：
#include <reg52.h>
sbit ADDR0 = P1^0;
sbit ADDR1 = P1^1;
sbit ADDR2 = P1^2;
sbit ADDR3 = P1^3;
sbit ENLED = P1^4;
sbit KEY_IN_1 = P2^4;
sbit KEY_IN_2 = P2^5;
sbit KEY_IN_3 = P2^6;
sbit KEY_IN_4 = P2^7;
sbit KEY_OUT_1 = P2^3;
sbit KEY_OUT_2 = P2^2;
sbit KEY_OUT_3 = P2^1;
sbit KEY_OUT_4 = P2^0;
unsigned char code LedChar[] = { //数码管显示字符转换表
0xC0, 0xF9, 0xA4, 0xB0, 0x99, 0x92, 0x82, 0xF8,
0x80, 0x90, 0x88, 0x83, 0xC6, 0xA1, 0x86, 0x8E
};
unsigned char LedBuff[6]={0xff,0xff,0xff,0xff,0xff,0xff}; //数码管显示缓冲区
unsigned char code KeyCodeMap[4][4] = { //矩阵按键编号到标准键盘键码的映射表
{ 0x31, 0x32, 0x33, 0x26 }, //数字键 1、数字键 2、数字键 3、向上键
{ 0x34, 0x35, 0x36, 0x25 }, //数字键 4、数字键 5、数字键 6、向左键
{ 0x37, 0x38, 0x39, 0x28 }, //数字键 7、数字键 8、数字键 9、向下键
{ 0x30, 0x1B, 0x0D, 0x27 } //数字键 0、ESC 键、 回车键、 向右键
};
unsigned char KeySta[4][4] = { //全部矩阵按键的当前状态
{1, 1, 1, 1}, {1, 1, 1, 1}, {1, 1, 1, 1}, {1, 1, 1, 1}
};
unsigned char THR0,TLR0;
void KeyDriver();
void ConfigTimer(unsigned long ms);
void main()
{
EA = 1; //使能总中断
ENLED = 0;
ADDR3 = 1;
ConfigTimer(1); //计算定时1ms，需要赋的初值，存在在 THR0,TLR0中
TMOD = TMOD & 0xF0;
TMOD = TMOD | 0x01; //设置定时器模式1 ,不影响高四位
TH0 = THR0; //定时器赋初值
TL0 = TLR0;
ET0= 1; //使能T0中断
TR0 = 1; //启动定时器T0
LedBuff[0] = LedChar[0]; //数码管默认显示0
while(1)
{
KeyDriver();
}
}
void ConfigTimer(unsigned long ms)
{
unsigned long temp;
temp = 65536 - ms*11059200/1000/12; //ms最大定时71ms
THR0 = (unsigned char)(temp>>8); //取计数值高八位 ，计数值不会超过65535，最多占用16位。
TLR0 = (char)temp; //取计数值低八位
}
void ShowNumber(unsigned long num)
{
signed char i;
unsigned char buf[6]; //将num六位数字按顺序放入buf数组中
for(i=0;i<=5;i++)
{
buf[i]=num%10;
num = num/10;
}
for(i=5;i>=1;i--) //从高位到低位依次扫描，直到某一位不为0
{
if(buf[i]==0)
{
LedBuff[i]=0xff; //如果高位为0，则关闭此对应数码管显示，否则跳出，保留buf[]中不为0的下角标在i中
}
else
{
break;
}
}
for(;i>=0;i--)
{
LedBuff[i]=LedChar[buf[i]]; //将各位数字取出，转换成数码管显示字符放入公有数组变量LedBuff[6]中
}
}
void KeyAction(unsigned char keycode)
{
static unsigned long result = 0;
static unsigned long addend = 0;
if((keycode>=0x30)&&(keycode<=0x39)) //输入的是数字
{
addend = (addend*10)+(keycode-0x30); //将原有数字顶上去
ShowNumber(addend);
}
else if(keycode == 0x26) //上键，执行加法操作
{
result += addend; //将上一个数字addend存在result中，清空addend，等待下一次数字
addend = 0;
ShowNumber(result);
}
else if(keycode == 0x0D) //回车键，作用和上键等同
{
result += addend; //将上一个数字addend存在result中，清空addend，等待下一次数字
addend = 0;
ShowNumber(result);
}
else if(keycode == 0x1B) //esc键，清零
{
addend = 0;
result = 0;
ShowNumber(addend);
}
}
void KeyDriver()
{
unsigned char i,j;
static unsigned char backup[4][4]={ //一定定义成静态，否则bug
{1,1,1,1}, {1,1,1,1},{1,1,1,1},{1,1,1,1}
};
for(i=0;i<4;i++)
{
for(j=0;j<4;j++)
{
if(KeySta[i][j]!=backup[i][j]) //当前按键状态和之前按键状态不一致，证明按键已经按下或者抬起
{
if(KeySta[i][j]==0) //如果当前按键状态为0，说明按键按下；在此我们只对按键按下动作响应
{
KeyAction(KeyCodeMap[i][j]); //将对应的按键转换成标准键盘码传入KeyAction中，根据传入的键盘码执行相应动作
}
backup[i][j]=KeySta[i][j]; //保存当前按键状态
}
}
}
}
void LedScan()
{
static unsigned char i = 0;
P0=0xff;
switch(i)
{
case 0: ADDR2=0;ADDR1=0;ADDR0=0;P0=LedBuff[i];i++;break;
case 1: ADDR2=0;ADDR1=0;ADDR0=1;P0=LedBuff[i];i++;break;
case 2: ADDR2=0;ADDR1=1;ADDR0=0;P0=LedBuff[i];i++;break;
case 3: ADDR2=0;ADDR1=1;ADDR0=1;P0=LedBuff[i];i++;break;
case 4: ADDR2=1;ADDR1=0;ADDR0=0;P0=LedBuff[i];i++;break;
case 5: ADDR2=1;ADDR1=0;ADDR0=1;P0=LedBuff[i];i=0;break;
default:break;
}
}
void KeyScan()
{
static unsigned char keyout = 0;
unsigned char i;
static unsigned char keybuf[4][4]={
{0xff,0xff,0xff,0xff},{0xff,0xff,0xff,0xff},{0xff,0xff,0xff,0xff},{0xff,0xff,0xff,0xff}
};
keybuf[keyout][0] = (keybuf[keyout][0]<<1)| KEY_IN_1;
keybuf[keyout][1] = (keybuf[keyout][1]<<1)| KEY_IN_2;
keybuf[keyout][2] = (keybuf[keyout][2]<<1)| KEY_IN_3;
keybuf[keyout][3] = (keybuf[keyout][3]<<1)| KEY_IN_4;
for(i=0;i<=3;i++)
{
if((keybuf[keyout][i]&0x0f)==0x00)
{
KeySta[keyout][i]=0;
}
else if((keybuf[keyout][i]&0x0f)==0x0f)
{
KeySta[keyout][i]=1;
}
else
{}
}
keyout++;
if(keyout>=4)
{keyout=0;}
switch(keyout) //扫描下一行
{
case 0: KEY_OUT_4=1;KEY_OUT_1=0;break;
case 1: KEY_OUT_1=1;KEY_OUT_2=0;break;
case 2: KEY_OUT_2=1;KEY_OUT_3=0;break;
case 3: KEY_OUT_3=1;KEY_OUT_4=0;break;
default:break;
}
}
void InterruptTimer0() interrupt 1
{
TH0=THR0;
TL0=TLR0;
LedScan();
KeyScan();
}