基于单片机设计的电子指南针(LSM303DLH模块(三轴磁场 + 三轴加速度)

#include <reg52.h>
#include <intrins.h>

// 定义LCD1602引脚连接
sbit RS = P0^0;    // 指令/数据选择线
sbit RW = P0^1;    // 读写选择线
sbit E = P0^2;     // 使能控制线

// 定义I2C总线连接
sbit SCL = P2^0;   // I2C串行时钟线
sbit SDA = P2^1;   // I2C串行数据线

// 函数声明
void delay_us(unsigned int us);
void delay_ms(unsigned int ms);

void I2C_Start();
void I2C_Stop();
void I2C_Ack();
void I2C_NoAck();
bit I2C_WaitAck();
void I2C_SendByte(unsigned char dat);
unsigned char I2C_ReceiveByte();

void LCD_Init();
void LCD_WriteCmd(unsigned char cmd);
void LCD_WriteData(unsigned char dat);
void LCD_SetCursor(unsigned char row, unsigned char col);
void LCD_DisplayString(unsigned char row, unsigned char col, unsigned char *str);

void Compass_Init();
unsigned char Compass_Read();
void Compass_Calculate(unsigned char raw_data, unsigned char *heading);

// 主函数
int main() {
    unsigned char heading;
    unsigned char str[16];

    LCD_Init();
    Compass_Init();

    while(1) {
        heading = Compass_Read();
        Compass_Calculate(heading, str);

        LCD_SetCursor(0, 0);
        LCD_DisplayString(0, 2, "Compass");
        LCD_SetCursor(1, 4);
        LCD_DisplayString(1, 6, str);

        delay_ms(500);
    }

    return 0;
}

// 延时函数，微秒级延时
void delay_us(unsigned int us) {
    while (us--) {
        _nop_();
        _nop_();
        _nop_();
        _nop_();
    }
}

// 延时函数，毫秒级延时
void delay_ms(unsigned int ms) {
    while (ms--) {
        delay_us(1000);
    }
}

// I2C总线开始
void I2C_Start() {
    SDA = 1;
    SCL = 1;
    delay_us(5);
    SDA = 0;
    delay_us(5);
    SCL = 0;
}

// I2C总线结束
void I2C_Stop() {
    SDA = 0;
    SCL = 1;
    delay_us(5);
    SDA = 1;
    delay_us(5);
}

// I2C总线发送应答信号
void I2C_Ack() {
    SDA = 0;
    SCL = 1;
    delay_us(5);
    SCL = 0;
    delay_us(5);
}

// I2C总线发送不应答信号
void I2C_NoAck() {
    SDA = 1;
    SCL = 1;
    delay_us(5);
    SCL = 0;
    delay_us(5);
}

// 等待I2C总线应答
bit I2C_WaitAck() {
    unsigned int i = 500;

    SDA = 1;
    SCL = 1;
    delay_us(1);

    while (SDA) {
        if (--i == 0) {
            I2C_Stop();
            return 0;
        }
    }

    SCL = 0;
    return 1;
}

// I2C总线发送字节
void I2C_SendByte(unsigned char dat) {
    unsigned char i;

    for (i = 0; i < 8; i++) {
        SDA = dat & 0x80;
        SCL = 1;
        delay_us(5);
        SCL = 0;
        delay_us(5);
        dat <<= 1;
    }
}

// I2C总线接收字节
unsigned char I2C_ReceiveByte() {
    unsigned char i;
    unsigned char dat = 0;

    SDA = 1;
    for (i = 0; i < 8; i++) {
        dat <<= 1;
        SCL = 1;
        delay_us(5);
        dat |= SDA;
        SCL = 0;
        delay_us(5);
    }

    return dat;
}

// LCD初始化
void LCD_Init() {
    delay_ms(50);
    LCD_WriteCmd(0x38);
    delay_us(50);
    LCD_WriteCmd(0x0C);
    delay_us(50);
    LCD_WriteCmd(0x01);
    delay_ms(5);
}

// LCD写入指令
void LCD_WriteCmd(unsigned char cmd) {
    RS = 0;
    RW = 0;
    P1 = cmd;
    E = 1;
    delay_us(5);
    E = 0;
    delay_us(5);
}

// LCD写入数据
void LCD_WriteData(unsigned char dat) {
    RS = 1;
    RW = 0;
    P1 = dat;
    E = 1;
    delay_us(5);
    E = 0;
    delay_us(5);
}

// LCD设置光标位置
void LCD_SetCursor(unsigned char row, unsigned char col) {
    unsigned char addr;

    if (row == 0) {
        addr = 0x80 + col;
    }
    else {
        addr = 0xC0 + col;
    }

    LCD_WriteCmd(addr);
    delay_us(5);
}

// LCD显示字符串
void LCD_DisplayString(unsigned char row, unsigned char col, unsigned char *str) {
    LCD_SetCursor(row, col);

    while (*str != '\0') {
        LCD_WriteData(*str++);
        delay_us(5);
    }
}

#define LSM303DLH_CTRL_REG1_A 0x20
#define LSM303DLH_OUT_X_H_A 0x29

// 指南针初始化
void Compass_Init() {
    // 设置控制寄存器1，使能XYZ轴加速度计，数据速率=50Hz
    I2C_Start();
    I2C_SendByte(0x3A); // LSM303DLH的I2C地址,注意写操作要在读写位上加低电平
    I2C_WaitAck();
    I2C_SendByte(LSM303DLH_CTRL_REG1_A);
    I2C_WaitAck();
    I2C_SendByte(0x27);
    I2C_WaitAck();
    I2C_Stop();
}

// 读取指南针数据
unsigned char Compass_Read() {
    unsigned char data;

    // 读取X轴高位数据寄存器
    I2C_Start();
    I2C_SendByte(0x3A);
    I2C_WaitAck();
    I2C_SendByte(LSM303DLH_OUT_X_H_A);
    I2C_WaitAck();
    I2C_Start();
    I2C_SendByte(0x3B);
    I2C_WaitAck();
    data = I2C_ReceiveByte();
    I2C_NoAck();
    I2C_Stop();

    return data;
}

#define LSM303DLH_OUT_X_H_M 0x03
#define LSM303DLH_OUT_Y_H_M 0x05
#define LSM303DLH_OUT_Z_H_M 0x07

// 计算指南针方向
void Compass_Calculate(unsigned char *heading) {
    int x, y, z;
    
    // 读取X轴、Y轴和Z轴的磁力计数据
    I2C_Start();
    I2C_SendByte(0x3C); // LSM303DLH的I2C地址,注意写操作要在读写位上加低电平
    I2C_WaitAck();
    I2C_SendByte(LSM303DLH_OUT_X_H_M);
    I2C_WaitAck();
    I2C_Start();
    I2C_SendByte(0x3D);
    I2C_WaitAck();
    x = (I2C_ReceiveByte() << 8) | I2C_ReceiveByte();
    x = -(x / 16); // 根据实际情况进行校正
    I2C_NoAck();
    I2C_Stop();
    
    I2C_Start();
    I2C_SendByte(0x3C);
    I2C_WaitAck();
    I2C_SendByte(LSM303DLH_OUT_Y_H_M);
    I2C_WaitAck();
    I2C_Start();
    I2C_SendByte(0x3D);
    I2C_WaitAck();
    y = (I2C_ReceiveByte() << 8) | I2C_ReceiveByte();
    y = -(y / 16); // 根据实际情况进行校正
    I2C_NoAck();
    I2C_Stop();
    
    I2C_Start();
    I2C_SendByte(0x3C);
    I2C_WaitAck();
    I2C_SendByte(LSM303DLH_OUT_Z_H_M);
    I2C_WaitAck();
    I2C_Start();
    I2C_SendByte(0x3D);
    I2C_WaitAck();
    z = (I2C_ReceiveByte() << 8) | I2C_ReceiveByte();
    z = -(z / 16); // 根据实际情况进行校正
    I2C_NoAck();
    I2C_Stop();
    
    // 计算方向角度
    *heading = atan2(y, x) * 180 / PI;
    if (*heading < 0) {
        *heading += 360;
    }
}