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hmc6352.cpp
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hmc6352.cpp
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/*
hmc6352 Arduino library
Copyright (C) 2012 Diego Fernandez Duran <diego@goedi.net>
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program 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 General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
Based on Vaibhav Bhawsar work:
http://recombine.net/blog/article/49/hmc6352-sparkfun-compass-and-arduino
*/
#include "hmc6352.h"
#include <Arduino.h>
#include <Wire.h>
HMC6352::HMC6352(int address)
{
this->address = address;
// Shift the device's documented slave address (0x42) 1 bit right
// This compensates for how the TWI library only wants the
// 7 most significant bits (with the high bit padded with 0)
slave_address = address >> 1;
// Start Wire library
Wire.begin();
}
int HMC6352::get_heading()
{
// Send a "A" command to the HMC6352
// This requests the current heading data
Wire.beginTransmission(slave_address);
// Send "Get Data" command
Wire.write("A");
Wire.endTransmission();
// The HMC6352 needs at least a 70us (microsecond) delay
// after this command. Using 10ms just makes it safe
delay(10);
// Read the 2 heading bytes, MSB first
// The resulting 16bit word is the compass heading in 10th's of a degree
// For example: a heading of 1345 would be 134.5 degrees
// Request the 2 byte heading (MSB comes first)
Wire.requestFrom(slave_address, 2);
byte headingData[2];
int i = 0;
while(Wire.available() && i < 2)
{
headingData[i] = Wire.read();
i++;
}
// Transform the data to integer
int headingValue = headingData[0]*256 + headingData[1];
return headingValue;
}