51单片机 – 独立按键消抖Coding练习

#include <reg52.h>

sbit ADDR0 = P1^0;
sbit ADDR1 = P1^1;
sbit ADDR2 = P1^2;
sbit ADDR3 = P1^3;
sbit ENLED = P1^4;
sbit keyIn1 = P2^4;
sbit keyIn2 = P2^5;
sbit keyIn3 = P2^6;
sbit keyIn4 = P2^7;
sbit keyOut1 = P2^3;
sbit keyOut2 = P2^2;
sbit keyOut3 = P2^1;
sbit keyOut4 = P2^0;

//数码管真值表
unsigned char code LedChar[16] = {
    0xC0, 0xF9, 0xA4, 0xB0, 0x99, 0x92, 0x82, 0xF8,
    0x80, 0x90, 0x88, 0x83, 0xC6, 0xA1, 0x86, 0x8E
};
//当前按键的状态
bit keySta = 1;

void main()
{
    bit keyBackup = 0;              //备份按键状态，保存前一次的按键状态
    unsigned char cnt = 15;         //按键计数，记录按键按下的次数

    EA = 1;                         //开启总中断
    ENLED = 0;                      //使能数码管的U3
    ADDR3 = 1;
    ADDR2 = 0;                      //选择数码管DS1进行显示
    ADDR1 = 0;
    ADDR0 = 0;
    TMOD &= 0xF0;                   //设置Timer0为模式1
    TMOD |= 0x01;
    TH0 = 0xF8;                     //为Timer0赋初值0xF8CD，定时2ms
    TL0 = 0xCD;
    ET0 = 1;                        //使能Timer0中断
    TR0 = 1;                        //启动Timer0
    P2 = 0xF7;                      //P2^3置0，即keyOut1输出低电平
    P0 = LedChar[cnt];              //显示按键次数的初始值15

    while (1)
    {
        if (keySta != keyBackup)    //如果Key当前值不得高于Key的备份值，说明按键有变化了
        {
            if(keySta == 0)         //如果Key当前值为0，说明当前按键已经按下状态
            {
                if (cnt == 0)
                {
                    cnt = 15;
                }
                else
                {
                    cnt--;
                }
                P0 = LedChar[cnt];  //计数值显示到数码管上
            }
            keyBackup = keySta;     //更新备份为当前值，以备下次比较使用
        }
    }
}

void InterruptTimer0() interrupt 1
{
    static unsigned char keyBuff = 0xFF;   //扫描缓冲区，保存一段时间内的扫描值，所以用static来修饰变量
    TH0 = 0xF8;                            //重载定时器初值
    TL0 = 0xCD;

    //每次进入中断左移1位，并且和keyIn1或运算。
    //或运算的作用是：左移1位后面补位为0，keyIn1是0的话或运算后还是0，keyIn1是1的话或运算后则为1
    keyBuff = (keyBuff << 1) | keyIn1;          

    if (keyBuff == 0x00)                  //如果连续8次都是0，则将keySta赋为0，说明按键为稳定的按下去的状态
    {
        keySta = 0;
    }
    if (keyBuff == 0xFF)                  //如果连续8次都是1，则将keySta赋为1，说明按键为稳定的弹起状态
    {
        keySta = 1;
    }
}