#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
    0x3f, 0x06, 0x5b, 0x4f, 0x66, 0x6d, 0x7d, 0x07,
    0x7f, 0x6f, 0x77, 0x7c, 0x39, 0x5e, 0x79, 0x71
};

void delay();

void main()
{
    bit keybuf = 1;  //按键值暂存，临时保存按键的扫描值
    bit backup = 1;  //按键值备份，保存前一次的扫描值
    unsigned char cnt = 0;  //按键计数，记录按键按下的次数

    ADDR3 = 1;
    ADDR2 = 0;
    ADDR1 = 0;
    ADDR0 = 0;
    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)
    {
        keybuf = KEY4;            //把当前扫描值暂存
        if (keybuf != backup)     //当前值与前次值不相等说明此时按键有动作
        {
           delay();              //延时大约10ms
            if (keybuf == KEY4)   //判断扫描值有没有发生改变，即按键抖动
            {
                if (backup == 0)  //如果前次值为0，则说明当前是弹起动作
                {
                    cnt++;        //按键次数+1
                    if (cnt >= 10)
                    {             //只用1个数码管显示，所以加到10就清零重新开始
                        cnt = 0;
                    }
                    P0 = LedChar[cnt];  //计数值显示到数码管上
                }
                backup = keybuf;  //更新备份为当前值，以备进行下次比较
            }
        }
    }
}
/* 软件延时函数，延时约10ms */
void delay()
{
    unsigned int i = 1000;
        
    while (i--);
}