mirror of https://github.com/ArduPilot/ardupilot
116 lines
3.1 KiB
C++
116 lines
3.1 KiB
C++
/*
|
|
AP_Compass.cpp - Arduino Library for HMC5843 I2C Magnetometer
|
|
Code by Jordi Muñoz and Jose Julio. DIYDrones.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.
|
|
|
|
Sensor is conected to I2C port
|
|
Sensor is initialized in Continuos mode (10Hz)
|
|
|
|
Variables:
|
|
heading : Magnetic heading
|
|
heading_X : Magnetic heading X component
|
|
heading_Y : Magnetic heading Y component
|
|
mag_X : Raw X axis magnetometer data
|
|
mag_Y : Raw Y axis magnetometer data
|
|
mag_Z : Raw Z axis magnetometer data
|
|
|
|
Methods:
|
|
init() : initialization of I2C and sensor
|
|
update() : update Sensor data
|
|
|
|
To do : Calibration of the sensor, code optimization
|
|
Mount position : UPDATED
|
|
Big capacitor pointing backward, connector forward
|
|
|
|
*/
|
|
|
|
|
|
extern "C" {
|
|
// AVR LibC Includes
|
|
#include <math.h>
|
|
#include "WConstants.h"
|
|
}
|
|
|
|
#include <Wire.h>
|
|
#include "AP_Compass.h"
|
|
|
|
#define COMPASS_ADDRESS 0x1E
|
|
|
|
// Constructors ////////////////////////////////////////////////////////////////
|
|
AP_Compass::AP_Compass()
|
|
{
|
|
}
|
|
|
|
// Public Methods //////////////////////////////////////////////////////////////
|
|
void
|
|
AP_Compass::init(void)
|
|
{
|
|
Wire.begin();
|
|
Wire.beginTransmission(COMPASS_ADDRESS);
|
|
Wire.send(0x02);
|
|
Wire.send(0x00); // Set continouos mode (default to 10Hz)
|
|
Wire.endTransmission(); // end transmission
|
|
}
|
|
|
|
// update Sensor data
|
|
void
|
|
AP_Compass::update()
|
|
{
|
|
int i = 0;
|
|
byte buff[6];
|
|
|
|
Wire.beginTransmission(COMPASS_ADDRESS);
|
|
Wire.send(0x03); // sends address to read from
|
|
Wire.endTransmission(); // end transmission
|
|
|
|
//Wire.beginTransmission(COMPASS_ADDRESS);
|
|
Wire.requestFrom(COMPASS_ADDRESS, 6); // request 6 bytes from device
|
|
while(Wire.available()){
|
|
buff[i] = Wire.receive(); // receive one byte
|
|
i++;
|
|
}
|
|
Wire.endTransmission(); // end transmission
|
|
|
|
// All bytes received?
|
|
if (i == 6) {
|
|
// MSB byte first, then LSB, X,Y,Z
|
|
mag_X = -((((int)buff[0]) << 8) | buff[1]); // X axis
|
|
mag_Y = ((((int)buff[2]) << 8) | buff[3]); // Y axis
|
|
mag_Z = -((((int)buff[4]) << 8) | buff[5]); // Z axis
|
|
}
|
|
}
|
|
|
|
void
|
|
AP_Compass::calculate(float roll, float pitch)
|
|
{
|
|
float head_X;
|
|
float head_Y;
|
|
float cos_roll;
|
|
float sin_roll;
|
|
float cos_pitch;
|
|
float sin_pitch;
|
|
|
|
cos_roll = cos(roll); // Optimization, you can get this out of the matrix DCM?
|
|
sin_roll = sin(roll);
|
|
cos_pitch = cos(pitch);
|
|
sin_pitch = sin(pitch);
|
|
|
|
// Tilt compensated Magnetic field X component:
|
|
head_X = mag_X * cos_pitch + mag_Y * sin_roll * sin_pitch + mag_Z * cos_roll * sin_pitch;
|
|
|
|
// Tilt compensated Magnetic field Y component:
|
|
head_Y = mag_Y * cos_roll - mag_Z * sin_roll;
|
|
|
|
// Magnetic heading
|
|
heading = atan2(-head_Y, head_X);
|
|
ground_course = (degrees(heading) + 180) * 100;
|
|
|
|
// Optimization for external DCM use. calculate normalized components
|
|
heading_X = cos(heading);
|
|
heading_Y = sin(heading);
|
|
}
|