在51开发板将503写入开发板的AT24C02储存器，并读出来显示在LCD上，按键控制数字加一，用c写出相应的代码

好的，下面是一份在51单片机开发板上实现的代码，仅供参考：

#include <reg51.h>
#include <intrins.h>

#define I2C_SCL P2_1
#define I2C_SDA P2_0
#define LCD_RS P1_0
#define LCD_RW P1_1
#define LCD_EN P1_2
#define LCD_DAT P0

void delay(unsigned int t)
{
    unsigned int i;
    while (t--)
    {
        for (i = 0; i < 125; i++);
    }
}

void i2c_start()
{
    I2C_SDA = 1;
    I2C_SCL = 1;
    delay(1);
    I2C_SDA = 0;
    delay(1);
    I2C_SCL = 0;
}

void i2c_stop()
{
    I2C_SDA = 0;
    I2C_SCL = 1;
    delay(1);
    I2C_SDA = 1;
    delay(1);
}

void i2c_write(unsigned char dat)
{
    unsigned char i;
    for (i = 0; i < 8; i++)
    {
        I2C_SCL = 0;
        I2C_SDA = dat & 0x80;
        delay(1);
        I2C_SCL = 1;
        delay(1);
        dat <<= 1;
    }
    I2C_SCL = 0;
    I2C_SDA = 1;
    delay(1);
    I2C_SCL = 1;
    delay(1);
}

unsigned char i2c_read(unsigned char ack)
{
    unsigned char i, dat = 0;
    I2C_SCL = 0;
    I2C_SDA = 1;
    delay(1);
    for (i = 0; i < 8; i++)
    {
        I2C_SCL = 1;
        delay(1);
        dat <<= 1;
        dat |= I2C_SDA;
        I2C_SCL = 0;
        delay(1);
    }
    I2C_SDA = ack;
    delay(1);
    I2C_SCL = 1;
    delay(1);
    I2C_SCL = 0;
    I2C_SDA = 1;
    return dat;
}

void lcd_write_cmd(unsigned char cmd)
{
    LCD_RS = 0;
    LCD_RW = 0;
    LCD_DAT = cmd;
    LCD_EN = 1;
    _nop_();
    _nop_();
    LCD_EN = 0;
}

void lcd_write_dat(unsigned char dat)
{
    LCD_RS = 1;
    LCD_RW = 0;
    LCD_DAT = dat;
    LCD_EN = 1;
    _nop_();
    _nop_();
    LCD_EN = 0;
}

void lcd_init()
{
    lcd_write_cmd(0x38);
    lcd_write_cmd(0x0c);
    lcd_write_cmd(0x06);
    lcd_write_cmd(0x01);
}

void lcd_clear()
{
    lcd_write_cmd(0x01);
}

void lcd_puts(unsigned char x, unsigned char y, unsigned char *str)
{
    if (y == 1) lcd_write_cmd(0x80 + x);
    else lcd_write_cmd(0xc0 + x);
    while (*str)
    {
        lcd_write_dat(*str++);
    }
}

void main()
{
    unsigned char num = 0;
    unsigned char str[16];
    unsigned char i2c_ack;

    lcd_init();
    lcd_clear();

    // 将数字503写入AT24C02储存器中
    i2c_start();
    i2c_write(0xa0);
    i2c_ack = i2c_read(1);
    i2c_write(0x00);
    i2c_ack = i2c_read(1);
    i2c_write(5);
    i2c_ack = i2c_read(1);
    i2c_write(0);
    i2c_ack = i2c_read(1);
    i2c_write(3);
    i2c_ack = i2c_read(0);
    i2c_stop();

    // 读取AT24C02储存器中的数据并显示在LCD屏幕上
    i2c_start();
    i2c_write(0xa0);
    i2c_ack = i2c_read(1);
    i2c_write(0x00);
    i2c_ack = i2c_read(1);
    i2c_start();
    i2c_write(0xa1);
    i2c_ack = i2c_read(1);
    num = i2c_read(0);
    i2c_stop();

    sprintf(str, "Number: %d", num);
    lcd_puts(0, 0, str);

    // 循环检测按键输入并更新数字
    while (1)
    {
        if (P3_4 == 0)
        {
            num++;
            sprintf(str, "Number: %d", num);
            lcd_clear();
            lcd_puts(0, 0, str);
            delay(500);
        }
    }
}

需要注意的是，51单片机开发板的I2C总线通信需要手动模拟，因此需要编写一些底层的I2C读写函数。此外，LCD显示屏的控制也需要编写相应的底层驱动程序。具体实现细节和调整可能会因为硬件设备的不同而有所变化，如果遇到问题，可以适当调整代码或者咨询专业人士。