mirror of https://github.com/ArduPilot/ardupilot
110 lines
3.2 KiB
C++
110 lines
3.2 KiB
C++
/*
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APM_Compass.cpp - Arduino Library for HMC5843 I2C Magnetometer
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Code by Jordi Muñoz and Jose Julio. DIYDrones.com
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This library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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Sensor is conected to I2C port
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Sensor is initialized in Continuos mode (10Hz)
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Variables:
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Heading : Magnetic heading
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Heading_X : Magnetic heading X component
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Heading_Y : Magnetic heading Y component
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Mag_X : Raw X axis magnetometer data
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Mag_Y : Raw Y axis magnetometer data
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Mag_Z : Raw Z axis magnetometer data
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Methods:
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Init() : Initialization of I2C and sensor
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Read() : Read Sensor data
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To do : Calibration of the sensor, code optimization
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Mount position : UPDATED
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Big capacitor pointing backward, connector forward
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*/
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extern "C" {
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// AVR LibC Includes
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#include <math.h>
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#include "WConstants.h"
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}
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#include <Wire.h>
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#include "APM_Compass.h"
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#define CompassAddress 0x1E
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// Constructors ////////////////////////////////////////////////////////////////
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APM_Compass_Class::APM_Compass_Class()
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{
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}
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// Public Methods //////////////////////////////////////////////////////////////
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void APM_Compass_Class::Init(void)
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{
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Wire.begin();
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Wire.beginTransmission(CompassAddress);
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Wire.send(0x02);
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Wire.send(0x00); // Set continouos mode (default to 10Hz)
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Wire.endTransmission(); //end transmission
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}
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// Read Sensor data
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void APM_Compass_Class::Read()
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{
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int i = 0;
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byte buff[6];
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Wire.beginTransmission(CompassAddress);
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Wire.send(0x03); //sends address to read from
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Wire.endTransmission(); //end transmission
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//Wire.beginTransmission(CompassAddress);
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Wire.requestFrom(CompassAddress, 6); // request 6 bytes from device
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while(Wire.available())
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{
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buff[i] = Wire.receive(); // receive one byte
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i++;
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}
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Wire.endTransmission(); //end transmission
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if (i==6) // All bytes received?
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{
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// MSB byte first, then LSB, X,Y,Z
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Mag_X = -((((int)buff[0]) << 8) | buff[1]); // X axis
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Mag_Y = ((((int)buff[2]) << 8) | buff[3]); // Y axis
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Mag_Z = -((((int)buff[4]) << 8) | buff[5]); // Z axis
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}
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}
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void APM_Compass_Class::Calculate(float roll, float pitch)
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{
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float Head_X;
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float Head_Y;
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float cos_roll;
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float sin_roll;
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float cos_pitch;
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float sin_pitch;
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cos_roll = cos(roll); // Optimizacion, se puede sacar esto de la matriz DCM?
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sin_roll = sin(roll);
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cos_pitch = cos(pitch);
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sin_pitch = sin(pitch);
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// Tilt compensated Magnetic field X component:
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Head_X = Mag_X*cos_pitch+Mag_Y*sin_roll*sin_pitch+Mag_Z*cos_roll*sin_pitch;
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// Tilt compensated Magnetic field Y component:
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Head_Y = Mag_Y*cos_roll-Mag_Z*sin_roll;
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// Magnetic Heading
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Heading = atan2(-Head_Y,Head_X);
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// Optimization for external DCM use. Calculate normalized components
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Heading_X = cos(Heading);
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Heading_Y = sin(Heading);
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}
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// make one instance for the user to use
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APM_Compass_Class APM_Compass; |