基于AT89X51的时钟与日期显示及按键控制

本项目旨在利用AT89X51单片机实现一个简单的时间和日期显示系统，用户可以通过按键在时间显示和日期显示之间进行切换。以下是具体的实现代码：

#include 

// 数码管显示编码表
char display[] = {0X3F, 0X06, 0X5B, 0X4F, 0X66, 0X6D, 0X7D, 0X07, 0X7F, 0X6F, 0XF7, 0X7C, 0X39, 0X5E, 0X79, 0X71};

char hour = 0, minute = 0, secOnd= 0; // 初始化时间为00:00:00
char year = 21, mOnth= 1, day = 1; // 初始化日期为2021年1月1日

// 延时函数
void delay(unsigned int xms) {
    unsigned int i, j;
    for (i = xms; i > 0; i--) {
        for (j = 240; j > 0; j--);
    }
}

// 显示数字
void displayNumber(char value) {
    P0 = display[value];
}

// 显示时间
void showTime() {
    P2 = 0xFE;
    displayNumber(hour / 10);
    delay(1);
    P2 = 0xFD;
    P0 = display[hour % 10] | 0x80;
    delay(1);
    P2 = 0xFB;
    displayNumber(minute / 10);
    delay(1);
    P2 = 0xF7;
    P0 = display[minute % 10] | 0x80;
    delay(1);
    P2 = 0xEF;
    displayNumber(second / 10);
    delay(1);
    P2 = 0xDF;
    P0 = display[second % 10];
    delay(1);
}

// 显示日期
void showDate() {
    P2 = 0xFE;
    displayNumber(year / 10);
    delay(1);
    P2 = 0xFD;
    P0 = display[year % 10] | 0x80;
    delay(1);
    P2 = 0xFB;
    displayNumber(month / 10);
    delay(1);
    P2 = 0xF7;
    P0 = display[month % 10] | 0x80;
    delay(1);
    P2 = 0xEF;
    displayNumber(day / 10);
    delay(1);
    P2 = 0xDF;
    P0 = display[day % 10];
    delay(1);
}

// 按键扫描
unsigned char scanKey() {
    unsigned char keyValue;
    P1 = 0x0F;
    if (P1 != 0x0F) {
        switch (P1) {
            case 0x0E: // 第一列
                P1 = 0xF0;
                switch (P1) {
                    case 0x70: keyValue = 12; break;
                    case 0xB0: keyValue = 8; break;
                    case 0xD0: keyValue = 4; break;
                    case 0xE0: keyValue = 0; break;
                }
                break;
            case 0x0D: // 第二列
                P1 = 0xF0;
                switch (P1) {
                    case 0x70: keyValue = 13; break;
                    case 0xB0: keyValue = 9; break;
                    case 0xD0: keyValue = 5; break;
                    case 0xE0: keyValue = 1; break;
                }
                break;
            case 0x0B: // 第三列
                P1 = 0xF0;
                switch (P1) {
                    case 0x70: keyValue = 14; break;
                    case 0xB0: keyValue = 10; break;
                    case 0xD0: keyValue = 6; break;
                    case 0xE0: keyValue = 2; break;
                }
                break;
            case 0x07: // 第四列
                P1 = 0xF0;
                switch (P1) {
                    case 0x70: keyValue = 15; break;
                    case 0xB0: keyValue = 11; break;
                    case 0xD0: keyValue = 7; break;
                    case 0xE0: keyValue = 3; break;
                }
                break;
        }
    }
    return keyValue;
}

// 判断闰年
char isLeapYear(int year) {
    if ((year % 400 == 0) || ((year % 4 == 0) && (year % 100 != 0)))
        return 29;
    else
        return 28;
}

// 获取月份天数
char getMonthDays(int year, char month) {
    switch (month) {
        case 4:
        case 6:
        case 9:
        case 11:
            return 30;
        case 2:
            return isLeapYear(year);
        default:
            return 31;
    }
}

char tick = 1;

// 定时器0中断服务程序
void timer0ISR() interrupt 1 {
    if (++tick == 20) {
        tick = 0;
        if (++secOnd== 60) {
            secOnd= 0;
            if (++minute == 60) {
                minute = 0;
                if (++hour == 24) {
                    hour = 0;
                    if (++day == getMonthDays(2000 + year, month) + 1) {
                        day = 1;
                        if (++mOnth== 13) {
                            mOnth= 1;
                            year++;
                        }
                    }
                }
            }
        }
    }
}

void main() {
    char key = 0x55;
    TMOD = 0x01; // T0模式1，16位定时器
    TH0 = -50000 / 256;
    TL0 = -50000 % 256;
    ET0 = 1; // 允许T0中断
    EA = 1; // 允许全局中断
    TR0 = 1; // 启动T0

    while (1) {
        key = scanKey();
        if (key == 1)
            showTime();
        else if (key == 2)
            showDate();
    }
}

以上代码实现了基本的时钟和日期显示功能，并通过按键进行界面切换。定时器0用于产生每秒一次的中断，以更新时间。按键扫描部分负责检测用户的输入并根据输入切换显示内容。