设计一个基于STC89C52单片机的计算器的程序

好的，下面是一个简单的基于STC89C52单片机的计算器的程序，可以进行加、减、乘、除四则运算：

#include <reg52.h>

sbit LCD_RS = P2^0;
sbit LCD_RW = P2^1;
sbit LCD_EN = P2^2;
sbit LCD_D4 = P2^4;
sbit LCD_D5 = P2^5;
sbit LCD_D6 = P2^6;
sbit LCD_D7 = P2^7;

void delay(unsigned int ms) // 延时函数
{
    unsigned int i, j;
    for (i = 0; i < ms; i++)
        for (j = 0; j < 114; j++);
}

void LCD_Write_Command(unsigned char cmmd) // 写入指令
{
    LCD_RS = 0;
    LCD_RW = 0;
    LCD_EN = 1;
    LCD_D7 = (cmmd & 0x80) >> 7;
    LCD_D6 = (cmmd & 0x40) >> 6;
    LCD_D5 = (cmmd & 0x20) >> 5;
    LCD_D4 = (cmmd & 0x10) >> 4;
    LCD_EN = 0;
    delay(1);
    LCD_EN = 1;
    LCD_D7 = (cmmd & 0x08) >> 3;
    LCD_D6 = (cmmd & 0x04) >> 2;
    LCD_D5 = (cmmd & 0x02) >> 1;
    LCD_D4 = (cmmd & 0x01);
    LCD_EN = 0;
    delay(1);
}

void LCD_Write_Data(unsigned char data) // 写入数据
{
    LCD_RS = 1;
    LCD_RW = 0;
    LCD_EN = 1;
    LCD_D7 = (data & 0x80) >> 7;
    LCD_D6 = (data & 0x40) >> 6;
    LCD_D5 = (data & 0x20) >> 5;
    LCD_D4 = (data & 0x10) >> 4;
    LCD_EN = 0;
    delay(1);
    LCD_EN = 1;
    LCD_D7 = (data & 0x08) >> 3;
    LCD_D6 = (data & 0x04) >> 2;
    LCD_D5 = (data & 0x02) >> 1;
    LCD_D4 = (data & 0x01);
    LCD_EN = 0;
    delay(1);
}

void LCD_Init() // 初始化LCD显示器
{
    LCD_Write_Command(0x02); // 返回Home
    LCD_Write_Command(0x28); // 4位数据线，2行显示，5x8字符
    LCD_Write_Command(0x0c); // 显示器开，不显示光标
    LCD_Write_Command(0x06); // 光标右移，不移动显示
    LCD_Write_Command(0x01); // 清屏
}

void LCD_Display_Char(unsigned char c) // 显示字符
{
    LCD_Write_Data(c);
}

void LCD_Display_String(unsigned char *str) // 显示字符串
{
    while (*str != '\0')
    {
        LCD_Display_Char(*str++);
    }
}

unsigned char Get_Key() // 获取按键值
{
    unsigned char key = 0xff;
    P1 = 0xff;
    if (P1 != 0xff)
    {
        delay(5);
        if (P1 != 0xff)
        {
            switch (P1)
            {
                case 0xfe: key = 0; break;
                case 0xfd: key = 1; break;
                case 0xfb: key = 2; break;
                case 0xf7: key = 3; break;
                case 0xef: key = 4; break;
                case 0xdf: key = 5; break;
                case 0xbf: key = 6; break;
                case 0x7f: key = 7; break;
            }
            while (P1 != 0xff);
        }
    }
    return key;
}

void main()
{
    unsigned char key, op = '+', flag = 0;
    unsigned int num1 = 0, num2 = 0, result = 0;
    LCD_Init();
    while (1)
    {
        key = Get_Key();
        if (key <= 9)
        {
            if (flag == 0)
            {
                num1 = num1 * 10 + key;
                LCD_Display_Char(key + '0');
            }
            else
            {
                num2 = num2 * 10 + key;
                LCD_Display_Char(key + '0');
            }
        }
        else if (key == 10)
        {
            if (op == '+')
            {
                result = num1 + num2;
            }
            else if (op == '-')
            {
                result = num1 - num2;
            }
            else if (op == '*')
            {
                result = num1 * num2;
            }
            else if (op == '/')
            {
                result = num1 / num2;
            }
            num1 = result;
            num2 = 0;
            flag = 0;
            LCD_Write_Command(0xc0);
            LCD_Display_String("=");
            LCD_Display_String(result);
        }
        else if (key == 11)
        {
            op = '+';
            flag = 1;
            LCD_Display_Char('+');
        }
        else if (key == 12)
        {
            op = '-';
            flag = 1;
            LCD_Display_Char('-');
        }
        else if (key == 13)
        {
            op = '*';
            flag = 1;
            LCD_Display_Char('*');
        }
        else if (key == 14)
        {
            op = '/';
            flag = 1;
            LCD_Display_Char('/');
        }
        else if (key == 15)
        {
            num1 = 0;
            num2 = 0;
            result = 0;
            op = '+';
            flag = 0;
            LCD_Write_Command(0x01);
            LCD_Write_Command(0x02);
        }
    }
}

该程序使用了4x4矩阵按键进行输入，LCD显示器进行输出。程序中定义了几个函数用于控制LCD显示器和获取按键值，并实现了加、减、乘、除四则运算。