Compass.cpp

/*
  Copyright (c) 2013 Arduino LLC. All right reserved.

  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 "Compass.h"
#include <Wire.h>

void Compass::begin(){
	Wire.begin();
}
float Compass::getReading(){
	_beginTransmission();
	_endTransmission();
	
  //time delays required by HMC6352 upon receipt of the command
  //Get Data. Compensate and Calculate New Heading : 6ms
  delay(6);

  Wire.requestFrom(HMC6352SlaveAddress, 2); //get the two data bytes, MSB and LSB

  //"The heading output data will be the value in tenths of degrees
  //from zero to 3599 and provided in binary format over the two bytes."
  byte MSB = Wire.read();
  byte LSB = Wire.read();

  float headingSum = (MSB << 8) + LSB; //(MSB / LSB sum)
  float headingInt = headingSum / 10; 
  
  return headingInt;
}

void Compass::_beginTransmission(){
  Wire.beginTransmission(HMC6352SlaveAddress);
  Wire.write(HMC6352ReadAddress);
}
void Compass::_endTransmission(){
  Wire.endTransmission();
}