HMC5883L.cpp

/*****************************************************************************/
//    Function:     Cpp file for HMC5883L
//  Hardware:    Grove - 3-Axis Digital Compass
//    Arduino IDE: Arduino-1.0
//    Author:     FrankieChu
//    Date:      Jan 10,2013
//    Version: v1.0
//    by www.seeedstudio.com
//
//  This library is free software; you can redistribute it and/or
//  modify it under the terms of the GNU Lesser General Public
//  License as published by the Free Software Foundation; either
//  version 2.1 of the License, or (at your option) any later version.
//
//  This library is distributed in the hope that it will be useful,
//  but WITHOUT ANY WARRANTY; without even the implied warranty of
//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
//  Lesser General Public License for more details.
//
//  You should have received a copy of the GNU Lesser General Public
//  License along with this library; if not, write to the Free Software
//  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
//
/*******************************************************************************/

#include <Arduino.h>
#include "HMC5883L.h"

HMC5883L::HMC5883L(TwoWire& w) {
    _wire = & w;
    m_Scale = 1;
}

void HMC5883L::initCompass() {

    delay(5);

    int error = setScale(1.3);                              // Set the scale of the compass.

    if (error != 0) {                                               // If there is an error, print it out.
        Serial.println(getErrorText(error));
    }

    error = setMeasurementMode(MEASUREMENT_CONTINUOUS);     // Set the measurement mode to Continuous

    if (error != 0) {                                               // If there is an error, print it out.
        Serial.println(getErrorText(error));
    }

    #if __Dbg
    //cout << "val_origin = " << val_origin << endl;
    //cout <<"init ok" << endl;
    #endif
}


int HMC5883L::getCompass() {
    // Retrived the scaled values from the compass (scaled to the configured scale).
    MagnetometerScaled scaled = readScaledAxis();

    // Values are accessed like so:
    int MilliGauss_OnThe_XAxis = scaled.XAxis;// (or YAxis, or ZAxis)

    // Calculate heading when the magnetometer is level, then correct for signs of axis.
    float heading = atan2(scaled.YAxis, MilliGauss_OnThe_XAxis);

    // Once you have your heading, you must then add your 'Declination Angle', which is the 'Error' of the magnetic field in your location.
    // Find yours here: http://www.magnetic-declination.com/
    // Mine is: -2??37' which is -2.617 Degrees, or (which we need) -0.0456752665 radians, I will use -0.0457
    // If you cannot find your Declination, comment out these two lines, your compass will be slightly off.
    float declinationAngle = -0.0457;
    heading += declinationAngle;

    // Correct for when signs are reversed.
    if (heading < 0) {
        heading += 2 * PI;
    }

    // Check for wrap due to addition of declination.
    if (heading > 2 * PI) {
        heading -= 2 * PI;
    }

    // Convert radians to degrees for readability.
    float headingDegrees = heading * 180 / M_PI;

    // Output the data via the serial port.

    int degree = headingDegrees * 10;

    return degree;
}



MagnetometerRaw HMC5883L::readRawAxis() {
    uint8_t* buffer = read(DATA_REGISTER_BEGIN, 6);
    MagnetometerRaw raw = MagnetometerRaw();
    raw.XAxis = (buffer[0] << 8) | buffer[1];
    raw.ZAxis = (buffer[2] << 8) | buffer[3];
    raw.YAxis = (buffer[4] << 8) | buffer[5];
    return raw;
}

MagnetometerScaled HMC5883L::readScaledAxis() {
    MagnetometerRaw raw = readRawAxis();
    MagnetometerScaled scaled = MagnetometerScaled();
    scaled.XAxis = raw.XAxis * m_Scale;
    scaled.ZAxis = raw.ZAxis * m_Scale;
    scaled.YAxis = raw.YAxis * m_Scale;
    return scaled;
}

short HMC5883L::setScale(float gauss) {
    uint8_t regValue = 0x00;

    /*  Some of these values; e.g. 1.3 - cause comparison
        issues with the compiler that the Arduino IDE uses.
    */
#define CLOSEENOUGH(x,y) (fabs(x-y)<0.001)

    if (CLOSEENOUGH(gauss, 0.88)) {
        regValue = 0x00;
        m_Scale = 0.73;
    } else if (CLOSEENOUGH(gauss, 1.3)) {
        regValue = 0x01;
        m_Scale = 0.92;
    } else if (CLOSEENOUGH(gauss, 1.9)) {
        regValue = 0x02;
        m_Scale = 1.22;
    } else if (CLOSEENOUGH(gauss, 2.5)) {
        regValue = 0x03;
        m_Scale = 1.52;
    } else if (CLOSEENOUGH(gauss, 4.0)) {
        regValue = 0x04;
        m_Scale = 2.27;
    } else if (CLOSEENOUGH(gauss, 4.7)) {
        regValue = 0x05;
        m_Scale = 2.56;
    } else if (CLOSEENOUGH(gauss, 5.6)) {
        regValue = 0x06;
        m_Scale = 3.03;
    } else if (CLOSEENOUGH(gauss, 8.1)) {
        regValue = 0x07;
        m_Scale = 4.35;
    } else {
        return ERRORCODE_1_NUM;
    }

    // Setting is in the top 3 bits of the register.
    regValue = regValue << 5;
    write(CONFIGURATION_REGISTERB, regValue);
    return 0;
}

short HMC5883L::setAverageSamples(uint8_t mode)
{
    uint8_t regValue = 0x00;
    
    if (mode == 1) {
        regValue = 0x10;
    } else if (mode == 2) {
        regValue = 0x30;
    } else if (mode == 4) {
        regValue = 0x50;
    } else if (mode == 8) {
        regValue = 0x80;
    } else {
        return ERRORCODE_2_NUM;
    }

    write(CONFIGURATION_REGISTERA, regValue);
    return 0;
}

short HMC5883L::setMeasurementMode(uint8_t mode) {
    write(MODE_REGISTER, mode);
    return 0;
}

void HMC5883L::write(short address, short data) {
    _wire->beginTransmission(HMC5883L_ADDRESS);
    _wire->write(address);
    _wire->write(data);
    _wire->endTransmission();
}

uint8_t* HMC5883L::read(short address, short length) {
    _wire->beginTransmission(HMC5883L_ADDRESS);
    _wire->write(address);
    _wire->endTransmission();


    _wire->requestFrom(HMC5883L_ADDRESS, length);

    if (_wire->available() == length) {
        for (uint8_t i = 0; i < length && i < sizeof(_buffer); i++) {
            _buffer[i] = _wire->read();
        }
    }


    return _buffer;
}

const char* HMC5883L::getErrorText(short errorCode) {
    if (ERRORCODE_1_NUM == errorCode) {
        return ERRORCODE_1;
    }
    if (ERRORCODE_2_NUM == errorCode) {
        return ERRORCODE_2;
    }

    return "Error not defined.";
}