51单片机 矩阵按键的扫描、消抖、动作分离

#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;

code unsigned char 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}
};

void main() {
    unsigned char i, j;
    unsigned char 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}
    };

    EA = 1;       //使能总中断
    ENLED = 0;    //选择数码管DS1进行显示
    ADDR3 = 1;
    ADDR2 = 0;
    ADDR1 = 0;
    ADDR0 = 0;
    TMOD = 0x01;  //设置T0为模式1
    TH0  = 0xFC;  //为T0赋初值0xFC67，定时1ms
    TL0  = 0x67;
    ET0  = 1;     //使能T0中断
    TR0  = 1;     //启动T0
    P0 = LedChar[0];   //默认显示0

    while (1) {
        for (i=0; i<4; i++) { //循环检测4*4的矩阵按键
            for (j=0; j<4; j++) {
                if (KeySta[i][j] != backup[i][j]) { //检测按键动作
                    if (KeySta[i][j] == 0) {  //按键按下时执行动作
                        P0 = LedChar[i*4 + j];       //将编号显示到数码管
                    }
                    backup[i][j] = KeySta[i][j];   //更新前一次的备份值
                }
            }
        }
    }
}
/* T0中断服务函数，扫描矩阵按键状态并消抖 */
void InterruptTimer0() interrupt 1 {
    unsigned char j;
    static unsigned char i = 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}
    };

    TH0 = 0xFC;  //重新加载初值
    TL0 = 0x67;
    //将一行的4个按键值移入缓冲区
    keybuf[i][0] = (keybuf[i][0] << 1) | KEY_IN_1;
    keybuf[i][1] = (keybuf[i][1] << 1) | KEY_IN_2;
    keybuf[i][2] = (keybuf[i][2] << 1) | KEY_IN_3;
    keybuf[i][3] = (keybuf[i][3] << 1) | KEY_IN_4;
    //消抖后更新按键状态
    for (j = 0; j < 4; j++) { //每行4个按键，所以循环4次
        if ((keybuf[i][j] & 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[i][j] = 0;
        }
        else if ((keybuf[i][j] & 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[i][j] = 1;
        }
    }
    //执行下一次的扫描输出
    switch (i) { //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_1 = 1; KEY_OUT_2 = 0; break;
        case 1: KEY_OUT_2 = 1; KEY_OUT_3 = 0; break;
        case 2: KEY_OUT_3 = 1; KEY_OUT_4 = 0; break;
        case 3: KEY_OUT_4 = 1; KEY_OUT_1 = 0; break;
        default: break;
    }
    i = ++i & 0x03;
}