MBED Example: How to use STMicro LSM303DLH 3 axis magnetometer with 3 axis accelerometer.

.from: http://mbed.org/users/shimniok/libraries/LSM303DLH/lpk7s5

XxXxXxXxXxXxXxXxXxXxXxXxXxXx LSM303DLH.cpp XxXxXxXxXxXxXxXxXxXxXxXxXxXx

/** LSM303DLH Interface Library
 *
 * Michael Shimniok http://bot-thoughts.com
 *
 * Based on test program by @tosihisa and
 *
 * Pololu sample library for LSM303DLH breakout by ryantm:
 *
 * Copyright (c) 2011 Pololu Corporation. For more information, see
 *
 * http://www.pololu.com/
 * http://forum.pololu.com/
 *
 * Permission is hereby granted, free of charge, to any person
 * obtaining a copy of this software and associated documentation
 * files (the "Software"), to deal in the Software without
 * restriction, including without limitation the rights to use,
 * copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following
 * conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
 * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
 * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
 * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 * OTHER DEALINGS IN THE SOFTWARE.
 */
#include "mbed.h"
#include "LSM303DLH.h"

#ifndef M_PI
#define M_PI 3.14159265358979323846
#endif

#define FILTER_SHIFT 6      // used in filtering acceleromter readings

const int addr_acc = 0x30;
const int addr_mag = 0x3c;

enum REG_ADDRS {
    /* --- Mag --- */
    CRA_REG_M   = 0x00,
    CRB_REG_M   = 0x01,
    MR_REG_M    = 0x02,
    OUT_X_M     = 0x03,
    OUT_Y_M     = 0x05,
    OUT_Z_M     = 0x07,
    /* --- Acc --- */
    CTRL_REG1_A = 0x20,
    CTRL_REG4_A = 0x23,
    OUT_X_A     = 0x28,
    OUT_Y_A     = 0x2A,
    OUT_Z_A     = 0x2C,
};

bool LSM303DLH::write_reg(int addr_i2c,int addr_reg, char v)
{
    char data[2] = {addr_reg, v};
    return LSM303DLH::_compass.write(addr_i2c, data, 2) == 0;
}

bool LSM303DLH::read_reg(int addr_i2c,int addr_reg, char *v)
{
    char data = addr_reg;
    bool result = false;
   
    __disable_irq();
    if ((_compass.write(addr_i2c, &data, 1) == 0) && (_compass.read(addr_i2c, &data, 1) == 0)){
        *v = data;
        result = true;
    }
    __enable_irq();
    return result;
}

bool LSM303DLH::read_reg_short(int addr_i2c,int addr_reg, short *v)
{
    char *pv = (char *)v;
    bool result;
   
    result =  read_reg(addr_i2c,addr_reg+0,pv+1);
    result &= read_reg(addr_i2c,addr_reg+1,pv+0);
 
    return result;
}

LSM303DLH::LSM303DLH(PinName sda, PinName scl):
    _compass(sda, scl), _offset_x(0), _offset_y(0), _offset_z(0), _scale_x(0), _scale_y(0), _scale_z(0), _filt_ax(0), _filt_ay(0), _filt_az(6000)
{
    char reg_v;
    _compass.frequency(100000);
       
    reg_v = 0;
    reg_v |= 0x01 << 5;     /* Normal mode  */
    reg_v |= 0x07;          /* X/Y/Z axis enable. */
    write_reg(addr_acc,CTRL_REG1_A,reg_v);
    reg_v = 0;
    read_reg(addr_acc,CTRL_REG1_A,&reg_v);

    reg_v = 0;
    reg_v |= 0x01 << 6;     /* 1: data MSB @ lower address */
    reg_v |= 0x01 << 4;     /* +/- 4g */
    write_reg(addr_acc,CTRL_REG4_A,reg_v);

    /* -- mag --- */
    reg_v = 0;
    reg_v |= 0x04 << 2;     /* Minimum data output rate = 15Hz */
    write_reg(addr_mag,CRA_REG_M,reg_v);

    reg_v = 0;
    //reg_v |= 0x01 << 5;     /* +-1.3Gauss */
    reg_v |= 0x07 << 5;     /* +-8.1Gauss */
    write_reg(addr_mag,CRB_REG_M,reg_v);

    reg_v = 0;              /* Continuous-conversion mode */
    write_reg(addr_mag,MR_REG_M,reg_v);
}


void LSM303DLH::setOffset(float x, float y, float z)
{
    _offset_x = x;
    _offset_y = y;
    _offset_z = z;  
}

void LSM303DLH::setScale(float x, float y, float z)
{
    _scale_x = x;
    _scale_y = y;
    _scale_z = z;
}

void LSM303DLH::read(vector &a, vector &m)
{
    short a_x, a_y, a_z;
    short m_x, m_y, m_z;
    //Timer t;
    //int usec1, usec2;
   
    //t.reset();
    //t.start();

    //usec1 = t.read_us();
    read_reg_short(addr_acc, OUT_X_A, &a_x);
    read_reg_short(addr_acc, OUT_Y_A, &a_y);
    read_reg_short(addr_acc, OUT_Z_A, &a_z);
    read_reg_short(addr_mag, OUT_X_M, &m_x);
    read_reg_short(addr_mag, OUT_Y_M, &m_y);
    read_reg_short(addr_mag, OUT_Z_M, &m_z);
    //usec2 = t.read_us();
   
    //if (debug) debug->printf("%d %d %d\n", usec1, usec2, usec2-usec1);

    // Perform simple lowpass filtering
    // Intended to stabilize heading despite
    // device vibration such as on a UGV
    _filt_ax += a_x - (_filt_ax >> FILTER_SHIFT);
    _filt_ay += a_y - (_filt_ay >> FILTER_SHIFT);
    _filt_az += a_z - (_filt_az >> FILTER_SHIFT);

    a.x = (float) (_filt_ax >> FILTER_SHIFT);
    a.y = (float) (_filt_ay >> FILTER_SHIFT);
    a.z = (float) (_filt_az >> FILTER_SHIFT);
   
    // offset and scale
    m.x = (m_x + _offset_x) * _scale_x;
    m.y = (m_y + _offset_y) * _scale_y;
    m.z = (m_z + _offset_z) * _scale_z;
}


// Returns the number of degrees from the -Y axis that it
// is pointing.
float LSM303DLH::heading()
{
    return heading((vector){0,-1,0});
}

float LSM303DLH::heading(vector from)
{
    vector a, m;

    this->read(a, m);
   
    ////////////////////////////////////////////////
    // compute heading      
    ////////////////////////////////////////////////

    vector temp_a = a;
    // normalize
    vector_normalize(&temp_a);
    //vector_normalize(&m);

    // compute E and N
    vector E;
    vector N;
    vector_cross(&m,&temp_a,&E);
    vector_normalize(&E);
    vector_cross(&temp_a,&E,&N);
   
    // compute heading
    float heading = atan2(vector_dot(&E,&from), vector_dot(&N,&from)) * 180/M_PI;
    if (heading < 0) heading += 360;
   
    return heading;
}

void LSM303DLH::frequency(int hz)
{
    _compass.frequency(hz);
}

XxXxXxXxXxXxXxXxXxXxXxXxXxXx LSM303DLH.h XxXxXxXxXxXxXxXxXxXxXxXxXxXx

#include "mbed.h"
#include "vector.h"

#ifndef M_PI
#define M_PI 3.14159265358979323846
#endif

/** Tilt-compensated compass interface Library for the STMicro LSM303DLH 3-axis magnetometer, 3-axis acceleromter
 *
 * Michael Shimniok http://bot-thoughts.com
 *
 * Based on test program by @tosihisa and
 *
 * Pololu sample library for LSM303DLH breakout by ryantm:
 *
 * Copyright (c) 2011 Pololu Corporation. For more information, see
 *
 * http://www.pololu.com/
 * http://forum.pololu.com/
 *
 * Permission is hereby granted, free of charge, to any person
 * obtaining a copy of this software and associated documentation
 * files (the "Software"), to deal in the Software without
 * restriction, including without limitation the rights to use,
 * copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following
 * conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
 * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
 * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
 * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 * OTHER DEALINGS IN THE SOFTWARE.
 *
 * @code
 * #include "mbed.h"
 * #include "LSM303DLH.h"
 *
 * Serial debug(USBTX,USBRX);
 * LSM303DLH compass(p28, p27);
 *
 * int main() {
 *   float hdg;
 *   debug.format(8,Serial::None,1);
 *   debug.baud(115200);
 *   debug.printf("LSM303DLH Test\x0d\x0a");
 *   compass.setOffset(29.50, -0.50, 4.00); // example calibration
 *   compass.setScale(1.00, 1.03, 1.21);    // example calibration
 *   while(1) {
 *     hdg = compass.heading();
 *     debug.printf("Heading: %.2f\n", hdg);
 *     wait(0.1);
 *   }
 * }
 * @endcode
 */
class LSM303DLH {
    public:
        /** Create a new interface for an LSM303DLH
         *
         * @param sda is the pin for the I2C SDA line
         * @param scl is the pin for the I2C SCL line
         */
        LSM303DLH(PinName sda, PinName scl);

        /** sets the x, y, and z offset corrections for hard iron calibration
         *
         * Calibration details here:
         *  http://mbed.org/users/shimniok/notebook/quick-and-dirty-3d-compass-calibration/
         *
         * If you gather raw magnetometer data and find, for example, x is offset
         * by hard iron by -20 then pass +20 to this member function to correct
         * for hard iron.
         *
         * @param x is the offset correction for the x axis
         * @param y is the offset correction for the y axis
         * @param z is the offset correction for the z axis
         */
        void setOffset(float x, float y, float z);
       
        /** sets the scale factor for the x, y, and z axes
         *
         * Calibratio details here:
         *  http://mbed.org/users/shimniok/notebook/quick-and-dirty-3d-compass-calibration/
         *
         * Sensitivity of the three axes is never perfectly identical and this
         * function can help to correct differences in sensitivity.  You're
         * supplying a multipler such that x, y and z will be normalized to the
         * same max/min values
         */
        void setScale(float x, float y, float z);

        /** read the raw accelerometer and compass values
         *
         * @param a is the accelerometer 3d vector, written by the function
         * @param m is the magnetometer 3d vector, written by the function
         */
        void read(vector &a, vector &m);
       
        /** returns the magnetic heading with respect to the y axis
         *
         */
        float heading(void);
       
        /** returns the heading with respect to the specified vector
         *
         */
        float heading(vector from);
   
        /** sets the I2C bus frequency
         *
         * @param frequency is the I2C bus/clock frequency, either standard (100000) or fast (400000)
         */
        void frequency(int hz);
   
    private:
        I2C _compass;
        float _offset_x;
        float _offset_y;
        float _offset_z;
        float _scale_x;
        float _scale_y;
        float _scale_z;
        long _filt_ax;
        long _filt_ay;
        long _filt_az;
      
        bool write_reg(int addr_i2c,int addr_reg, char v);
        bool read_reg(int addr_i2c,int addr_reg, char *v);
        bool read_reg_short(int addr_i2c,int addr_reg, short *v);
};
 

XxXxXxXxXxXxXxXxXxXxXxXxXxXx vector.cpp XxXxXxXxXxXxXxXxXxXxXxXxXxXx

 #include <vector.h>
#include <math.h>

void vector_cross(const vector *a,const vector *b, vector *out)
{
  out->x = a->y*b->z - a->z*b->y;
  out->y = a->z*b->x - a->x*b->z;
  out->z = a->x*b->y - a->y*b->x;
}

float vector_dot(const vector *a,const vector *b)
{
  return a->x*b->x+a->y*b->y+a->z*b->z;
}

void vector_normalize(vector *a)
{
  float mag = sqrt(vector_dot(a,a));
  a->x /= mag;
  a->y /= mag;
  a->z /= mag;
}

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 #ifndef vector_h
#define vector_h
typedef struct vector
{
  float x, y, z;
} vector;

extern void vector_cross(const vector *a, const vector *b, vector *out);
extern float vector_dot(const vector *a,const vector *b);
extern void vector_normalize(vector *a);
#endif

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MBED Example: How to use geographical position and calculation using latitude and longitude

.from: http://mbed.org/users/shimniok/libraries/GeoPosition/ly4w47

XxXxXxXxXxXxXxXxXxXxXxXxXxXxXxXxXx GeoPosition.cpp XxXxXxXxXxXxXxXxXxXxXxXxXxXxXxXxXx

#include "GeoPosition.h"
#include <math.h>

// Earth's mean radius in meters
#define EARTHRADIUS 6371000.0

GeoPosition::GeoPosition(): _R(EARTHRADIUS), _latitude(0.0), _longitude(0.0)
{
}

GeoPosition::GeoPosition(double latitude, double longitude): _R(EARTHRADIUS), _latitude(latitude), _longitude(longitude)
{
}
   
/*
double GeoPosition::easting()
{
}

double GeoPosition::northing()
{
}
*/

double GeoPosition::latitude()
{
    return _latitude;
}

double GeoPosition::longitude()
{
    return _longitude;
}

void GeoPosition::set(double latitude, double longitude)
{
    _latitude = latitude;
    _longitude = longitude;
}

void GeoPosition::set(GeoPosition pos)
{
    _latitude = pos.latitude();
    _longitude = pos.longitude();
}

/*
void GeoPosition::set(UTM coord)
{
}
*/

void GeoPosition::move(float course, float distance)
{
    double d = distance / _R;
    double c = radians(course);
    double rlat1 = radians(_latitude);
    double rlon1 = radians(_longitude);

    double rlat2 = asin(sin(rlat1)*cos(d) + cos(rlat1)*sin(d)*cos(c));
    double rlon2 = rlon1 + atan2(sin(c)*sin(d)*cos(rlat1), cos(d)-sin(rlat1)*sin(rlat2));

    _latitude  = degrees(rlat2);
    _longitude = degrees(rlon2);

    // bring back within the range -180 to +180
    while (_longitude < -180.0) _longitude += 360.0;
    while (_longitude > 180.0) _longitude -= 360.0;
}

/*
void GeoPosition::move(Direction toWhere)
{
}

Direction GeoPosition::direction(GeoPosition startingPoint)
{
}
*/

float GeoPosition::bearing(GeoPosition from)
{
    double lat1 = radians(from.latitude());
    double lon1 = radians(from.longitude());
    double lat2 = radians(_latitude);
    double lon2 = radians(_longitude);
    double dLon = lon2 - lon1;

    double y = sin(dLon) * cos(lat2);
    double x = cos(lat1) * sin(lat2) - sin(lat1) * cos(lat2) * cos(dLon);

    return degrees(atan2(y, x));
}

/*
float GeoPosition::bearing(LatLong startingPoint)
{
}

float GeoPosition::bearing(UTM startingPoint)
{
}
*/

float GeoPosition::distance(GeoPosition from)
{
    double lat1 = radians(from.latitude());
    double lon1 = radians(from.longitude());
    double lat2 = radians(_latitude);
    double lon2 = radians(_longitude);
    double dLat = lat2 - lat1;
    double dLon = lon2 - lon1;

    double a = sin(dLat/2.0) * sin(dLat/2.0) +
               cos(lat1) * cos(lat2) *
               sin(dLon/2.0) * sin(dLon/2.0);
    double c = 2.0 * atan2(sqrt(a), sqrt(1-a));
   
    return _R * c;
}

/*
float GeoPosition::distance(LatLong startingPoint)
{
}

float GeoPosition::distance(UTM startingPoint)
{
}
*/

void GeoPosition::setTimestamp(int time) {
    _time = time;
}

int GeoPosition::getTimestamp(void) {
    return _time;
}


   

XxXxXxXxXxXxXxXxXxXxXxXxXxXxXxXxXx GeoPosition.h XxXxXxXxXxXxXxXxXxXxXxXxXxXxXxXxXx

#ifndef __GEOPOSITION_H
#define __GEOPOSITION_H

#ifndef _PI
#define _PI 3.141592653
#endif

#define degrees(x) ((x)*180/_PI)
#define radians(x) ((x)*_PI/180)

/** Geographical position and calculation. Most of this comes from http://www.movable-type.co.uk/scripts/latlong.html
 *
 */
class GeoPosition {
public:

    /** Create a new emtpy position object
     *
     */
    GeoPosition();

    /** Create a new position with the specified latitude and longitude. See set()
     *
     *  @param latitude is the latitude to set
     *  @param longitude is the longitude to set
     */
    GeoPosition(double latitude, double longitude);
   
    /** Get the position's latitude
     *
     *  @returns the position's latitude
     */
    double latitude();
   
    /** Get the position's longitude
     *
     *  @returns the position's longitude
     */
    double longitude();
   
    /** Set the position's location to another position's coordinates
     *
     *  @param pos is another position from which coordinates will be copied
     */
    void set(GeoPosition pos);
   
    /** Set the position's location to the specified coordinates
     *
     *  @param latitude is the new latitude to set
     *  @param longitude is the new longitude to set
     */
    void set(double latitude, double longitude);
   
    /** Move the location of the position by the specified distance and in
     *  the specified direction
     *
     *  @param course is the direction of movement in degrees, absolute not relative
     *  @param distance is the distance of movement along the specified course in meters
     */
    void move(float course, float distance);

    /** Get the bearing from the specified origin position to this position.  To get
     *  relative bearing, subtract the result from your heading.
     *
     *  @param from is the position from which to calculate bearing
     *  @returns the bearing in degrees
     */
    float bearing(GeoPosition from);
   
    /** Get the distance from the specified origin position to this position
     *
     *  @param from is the position from which to calculate distance
     *  @returns the distance in meters
     */
    float distance(GeoPosition from);
   
    /** Set an arbitrary timestamp on the position
     *
     * @param timestamp is an integer timestamp, eg., seconds, milliseconds, or whatever
     */
     void setTimestamp(int time);

    /** Return a previously set timestamp on the position
     *
     * @returns the timestamp (e.g., seconds, milliseconds, etc.)
     */    
     int getTimestamp(void);

private:
    double _R;          /** Earth's mean radius */
    double _latitude;   /** The position's latitude */
    double _longitude;  /** The position's longitude */
    double _northing;   /** The position's UTM northing coordinate */
    double _easting;    /** The position's UTM easting coordinate */
    int _time;          /** Timestamp */
};

#endif

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