单片机长短按键的实现代码含注释 -

#include <reg52.h>
sbit BUZZ = P1^6;
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[7] = { //数码管+独立LED显示缓冲区
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF
};
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 long pdata KeyDownTime[4][4] = { //每个按键按下的持续时间，单位ms
{0, 0, 0, 0}, {0, 0, 0, 0}, {0, 0, 0, 0}, {0, 0, 0, 0}
};
bit enBuzz = 0; //蜂鸣器使能标志
bit flag1s = 0; //1秒定时标志
bit flagStart = 0; //倒计时启动标志
unsigned char T0RH = 0; //T0重载值的高字节
unsigned char T0RL = 0; //T0重载值的低字节
unsigned int CountDown = 0; //倒计时计数器
void ConfigTimer0(unsigned int ms);
void ShowNumber(unsigned long num);
void KeyDriver();
void main()
{
EA = 1; //使能总中断
ENLED = 0; //选择数码管和独立LED
ADDR3 = 1;
ConfigTimer0(1); //配置T0定时1ms
ShowNumber(0); //上电显示0
while (1)
{
KeyDriver(); //调用按键驱动函数
if (flagStart && flag1s) //倒计时启动且1秒定时到达时，处理倒计时
{
flag1s = 0;
if (CountDown > 0) //倒计时未到0时，计数器递减
{
CountDown--;
ShowNumber(CountDown); //刷新倒计时数显示
if (CountDown == 0) //减到0时，执行声光报警
{
enBuzz = 1; //启动蜂鸣器发声
LedBuff[6] = 0x00; //点亮独立LED
}
}
}
}
}
/* 配置并启动T0，ms-T0定时时间 */
void ConfigTimer0(unsigned int ms)
{
unsigned long tmp; //临时变量
tmp = 11059200 / 12; //定时器计数频率
tmp = (tmp * ms) / 1000; //计算所需的计数值
tmp = 65536 - tmp; //计算定时器重载值
tmp = tmp + 28; //补偿中断响应延时造成的误差
T0RH = (unsigned char)(tmp>>8); //定时器重载值拆分为高低字节
T0RL = (unsigned char)tmp;
TMOD &= 0xF0; //清零T0的控制位
TMOD |= 0x01; //配置T0为模式1
TH0 = T0RH; //加载T0重载值
TL0 = T0RL;
ET0 = 1; //使能T0中断
TR0 = 1; //启动T0
}
/* 将一个无符号长整型的数字显示到数码管上，num-待显示数字 */
void ShowNumber(unsigned long num)
{
signed char i;
unsigned char buf[6];
for (i=0; i<6; i++) //把长整型数转换为6位十进制的数组
{
buf[i] = num % 10;
num = num / 10;
}
for (i=5; i>=1; i--) //从最高位起，遇到0转换为空格，遇到非0则退出循环
{
if (buf[i] == 0)
LedBuff[i] = 0xFF;
else
break;
}
for ( ; i>=0; i--) //剩余低位都如实转换为数码管显示字符
{
LedBuff[i] = LedChar[buf[i]];
}
}
/* 按键动作函数，根据键码执行相应的操作，keycode-按键键码 */
void KeyAction(unsigned char keycode) //按键动作函数，根据键码执行相应动作
{
if (keycode == 0x26) //向上键，倒计时设定值递增
{
if (CountDown < 9999) //最大计时9999秒
{
CountDown++;
ShowNumber(CountDown);
}
}
else if (keycode == 0x28) //向下键，倒计时设定值递减
{
if (CountDown > 1) //最小计时1秒
{
CountDown--;
ShowNumber(CountDown);
}
}
else if (keycode == 0x0D) //回车键，启动倒计时
{
flagStart = 1; //启动倒计时
}
else if (keycode == 0x1B) //Esc键，取消倒计时
{
enBuzz = 0; //关闭蜂鸣器
LedBuff[6] = 0xFF; //关闭独立LED
flagStart = 0; //停止倒计时
CountDown = 0; //倒计时数归零
ShowNumber(CountDown);
}
}
/* 按键驱动函数，检测按键动作，调度相应动作函数，需在主循环中调用 */
void KeyDriver()
{
unsigned char i, j;
static unsigned char pdata backup[4][4] = { //按键值备份，保存前一次的值
{1, 1, 1, 1}, {1, 1, 1, 1}, {1, 1, 1, 1}, {1, 1, 1, 1}
};
static unsigned long pdata TimeThr[4][4] = { //快速输入执行的时间阈值
{1000, 1000, 1000, 1000}, {1000, 1000, 1000, 1000},
{1000, 1000, 1000, 1000}, {1000, 1000, 1000, 1000}
};
for (i=0; i<4; i++) //循环扫描4*4的矩阵按键
{
for (j=0; j<4; j++)
{
if (backup[i][j] != KeySta[i][j]) //检测按键动作
{
if (backup[i][j] != 0) //按键按下时执行动作
{
KeyAction(KeyCodeMap[i][j]); //调用按键动作函数
}
backup[i][j] = KeySta[i][j]; //刷新前一次的备份值
}
if (KeyDownTime[i][j] > 0) //检测执行快速输入
{
if (KeyDownTime[i][j] >= TimeThr[i][j])
{ //达到阈值时执行一次动作
KeyAction(KeyCodeMap[i][j]); //调用按键动作函数
TimeThr[i][j] += 200; //时间阈值增加200ms，以准备下次执行
}
}
else //按键弹起时复位阈值时间
{
TimeThr[i][j] = 1000; //恢复1s的初始阈值时间
}
}
}
}
/* 按键扫描函数，需在定时中断中调用 */
void KeyScan()
{
unsigned char i;
static unsigned char keyout = 0; //矩阵按键扫描输出索引
static unsigned char keybuf[4][4] = { //矩阵按键扫描缓冲区
{0xFF, 0xFF, 0xFF, 0xFF}, {0xFF, 0xFF, 0xFF, 0xFF},
{0xFF, 0xFF, 0xFF, 0xFF}, {0xFF, 0xFF, 0xFF, 0xFF}
};
//将一行的4个按键值移入缓冲区
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;
//消抖后更新按键状态
for (i=0; i<4; i++) //每行4个按键，所以循环4次
{
if ((keybuf[keyout][i] & 0x0F) == 0x00)
{ //连续4次扫描值为0，即4*4ms内都是按下状态时，可认为按键已稳定的按下
KeySta[keyout][i] = 0;
KeyDownTime[keyout][i] += 4; //按下的持续时间累加
}
else if ((keybuf[keyout][i] & 0x0F) == 0x0F)
{ //连续4次扫描值为1，即4*4ms内都是弹起状态时，可认为按键已稳定的弹起
KeySta[keyout][i] = 1;
KeyDownTime[keyout][i] = 0; //按下的持续时间清零
}
}
//执行下一次的扫描输出
keyout++; //输出索引递增
keyout &= 0x03; //索引值加到4即归零
switch (keyout) //根据索引，释放当前输出引脚，拉低下次的输出引脚
{
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;
}
}
/* LED动态扫描刷新函数，需在定时中断中调用 */
void LedScan()
{
static unsigned char i = 0; //动态扫描索引
P0 = 0xFF; //关闭所有段选位，显示消隐
P1 = (P1 & 0xF8) | i; //位选索引值赋值到P1口低3位
P0 = LedBuff[i]; //缓冲区中索引位置的数据送到P0口
if (i < 6) //索引递增循环，遍历整个缓冲区
i++;
else
i = 0;
}
/* T0中断服务函数，完成数码管、按键扫描与秒定时 */
void InterruptTimer0() interrupt 1
{
static unsigned int tmr1s = 0; //1秒定时器
TH0 = T0RH; //重新加载重载值
TL0 = T0RL;
if (enBuzz) //蜂鸣器发声处理
BUZZ = ~BUZZ; //驱动蜂鸣器发声
else
BUZZ = 1; //关闭蜂鸣器
LedScan(); //LED扫描显示
KeyScan(); //按键扫描
if (flagStart) //倒计时启动时处理1秒定时
{
tmr1s++;
if (tmr1s >= 1000)
{
tmr1s = 0;
flag1s = 1;
}
}
else //倒计时未启动时1秒定时器始终归零
{
tmr1s = 0;
}
}

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