51单片机简易计算器矩阵键盘4行四列两个四位数码管显示代码

以下是基于51单片机的简易计算器矩阵键盘4行四列两个四位数码管显示代码，其中使用了定时器中断和数码管扫描技术：

#include <reg51.h>

#define uchar unsigned char
#define uint unsigned int

sbit SCL = P1^0; // I2C 时钟
sbit SDA = P1^1; // I2C 数据

sbit D1 = P2^7;
sbit D2 = P2^6;
sbit D3 = P2^5;
sbit D4 = P2^4;
sbit L1 = P2^3;
sbit L2 = P2^2;
sbit L3 = P2^1;
sbit L4 = P2^0;

uchar cnt, key, flag;
uchar num1[4], num2[4], num3[4];
uchar op, result[4];

void delay(uint x) // 延时函数
{
    uint i, j;
    for (i = x; i > 0; i--)
        for (j = 110; j > 0; j--);
}

void i2c_start() // I2C 起始信号
{
    SDA = 1;
    SCL = 1;
    delay(1);
    SDA = 0;
    delay(1);
    SCL = 0;
}

void i2c_stop() // I2C 停止信号
{
    SDA = 0;
    SCL = 1;
    delay(1);
    SDA = 1;
    delay(1);
}

void i2c_write(uchar dat) // I2C 写入数据
{
    uchar i;
    for (i = 0; i < 8; i++)
    {
        SDA = dat & 0x80;
        SCL = 1;
        delay(1);
        SCL = 0;
        dat <<= 1;
    }
    SDA = 1;
    SCL = 1;
    delay(1);
    SCL = 0;
}

uchar keypad_scan() // 扫描矩阵键盘
{
    uchar key_val = 0;
    uchar row, col;

    for (col = 0; col < 4; col++)
    {
        P0 = 0x0f << 4;
        P0 |= (1 << col) << 4;
        delay(1);
        row = P0 >> 4;
        if (row != 0x0f)
        {
            switch (row)
            {
                case 0x07: key_val = col + 1; break;
                case 0x0b: key_val = col + 5; break;
                case 0x0d: key_val = col + 9; break;
                case 0x0e: key_val = col + 13; break;
            }
            while (row != 0x0f)
            {
                delay(1);
                row = P0 >> 4;
            }
            break;
        }
    }
    return key_val;
}

void display() // 数码管显示函数
{
    uchar i;
    uchar code table[] = { // 数码管字符编码
        0x3f, 0x06, 0x5b, 0x4f, 0x66, 0x6d, 0x7d, 0x07,
        0x7f, 0x6f, 0x77, 0x7c, 0x39, 0x5e, 0x79, 0x71
    };

    for (i = 0; i < 4; i++)
    {
        switch (i)
        {
            case 0: L1 = 0; L2 = 1; L3 = 1; L4 = 1; break;
            case 1: L1 = 1; L2 = 0; L3 = 1; L4 = 1; break;
            case 2: L1 = 1; L2 = 1; L3 = 0; L4 = 1; break;
            case 3: L1 = 1; L2 = 1; L3 = 1; L4 = 0; break;
        }

        if (flag == 1) // 显示 num1
        {
            D1 = 0; D2 = 0; D3 = 0; D4 = 0;
            P0 = table[num1[i]];
        }
        else if (flag == 2) // 显示 num2
        {
            D1 = 0; D2 = 0; D3 = 0; D4 = 0;
            P0 = table[num2[i]];
        }
        else if (flag == 3) // 显示 num1 + num2
        {
            D1 = 0; D2 = 0; D3 = 0; D4 = 0;
            P0 = table[num1[i]];
            delay(1);
            switch (op)
            {
                case 1: P0 = table[10]; break; // +
                case 2: P0 = table[11]; break; // -
                case 3: P0 = table[12]; break; // *
                case 4: P0 = table[13]; break; // /
            }
            delay(1);
            P0 = table[num2[i]];
        }
        else if (flag == 4) // 显示结果
        {
            D1 = 0; D2 = 0; D3 = 0; D4 = 0;
            P0 = table[result[i]];
        }

        delay(1);
    }
}

void timer0_init() // 定时器0初始化函数
{
    TMOD &= 0xf0;
    TMOD |= 0x01;
    TH0 = 0xfc;
    TL0 = 0x67;
    EA = 1;
    ET0 = 1;
    TR0 = 1;
}

void timer0_isr() interrupt 1 // 定时器0中断服务函数
{
    TH0 = 0xfc;
    TL0 = 0x67;
    cnt++;
    if (cnt >= 100)
    {
        cnt = 0;
        key = keypad_scan();
        if (key != 0)
        {
            switch (key)
            {
                case 1: num1[3]++; break;
                case 2: num1[2]++; break;
                case 3: num1[1]++; break;
                case 4: op = 1; flag = 2; break; // +
                case 5: num2[3]++; break;
                case 6: num2[2]++; break;
                case 7: num2[1]++; break;
                case 8: op = 2; flag = 2; break; // -
                case 9: num1[0]++; break;
                case 10: num2[0]++; break;
                case 11: op = 3; flag = 2; break; // *
                case 12: flag = 3; break; // =
                case 13: num1[3] = num1[2] = num1[1] = num1[0] = 0;
                         num2[3] = num2[2] = num2[1] = num2[0] = 0;
                         result[3] = result[2] = result[1] = result[0] = 0;
                         flag = 1; break; // C
                case 14: op = 4; flag = 2; break; // /
            }
        }

        if (num1[3] >= 10) { num1[3] = 0; num1[2]++; }
        if (num1[2] >= 10) { num1[2] = 0; num1[1]++; }
        if (num1[1] >= 10) { num1[1] = 0; num1[0]++; }
        if (num2[3] >= 10) { num2[3] = 0; num2[2]++; }
        if (num2[2] >= 10) { num2[2] = 0; num2[1]++; }
        if (num2[1] >= 10) { num2[1] = 0; num2[0]++; }

        if (flag == 3) // 计算结果
        {
            uchar n1 = num1[3] * 1000 + num1[2] * 100 + num1[1] * 10 + num1[0];
            uchar n2 = num2[3] * 1000 + num2[2] * 100 + num2[1] * 10 + num2[0];
            switch (op)
            {
                case 1: n1 += n2; break;
                case 2: n1 -= n2; break;
                case 3: n1 *= n2; break;
                case 4: n1 /= n2; break;
            }
            result[3] = n1 / 1000;
            result[2] = (n1 % 1000) / 100;
            result[1] = (n1 % 100) / 10;
            result[0] = n1 % 10;
            flag = 4;
        }

        display();
    }
}

void main()
{
    flag = 1;
    timer0_init();
    while (1);
}

该代码实现了四则运算（加、减、乘、除）和清零功能。在使用时，需要连接矩阵键盘和两个四位数码管，并按照注释修改代码中相应的引脚定义。