HMC5883L 3-axis digital compass module GY-273

Arduino code example:

Library

#include <Wire.h>
#include <HMC5883L.h>

HMC5883L compass;


void setup(){
 Serial.begin(9600);
 Wire.begin();
 
 compass = HMC5883L(); //new instance of HMC5883L library
 setupHMC5883L(); //setup the HMC5883L
}

// Our main program loop.
void loop(){
 
 float heading = getHeading();
 Serial.println(heading);
 delay(100); //only here to slow down the serial print

}

void setupHMC5883L(){
 //Setup the HMC5883L, and check for errors
 int error; 
 error = compass.SetScale(1.3); //Set the scale of the compass.
 if(error != 0) Serial.println(compass.GetErrorText(error)); //check if there is an error, and print if so

 error = compass.SetMeasurementMode(Measurement_Continuous); // Set the measurement mode to Continuous
 if(error != 0) Serial.println(compass.GetErrorText(error)); //check if there is an error, and print if so
}

float getHeading(){
 //Get the reading from the HMC5883L and calculate the heading
 MagnetometerScaled scaled = compass.ReadScaledAxis(); //scaled values from compass.
 float heading = atan2(scaled.YAxis, scaled.XAxis);

 // Correct for when signs are reversed.
 if(heading < 0) heading += 2*PI;
 if(heading > 2*PI) heading -= 2*PI;

 return heading * RAD_TO_DEG; //radians to degrees
}