hi
i want to use gy271 HMC5883 .
i use this code :
#include <Wire.h>
#include <Adafruit_Sensor.h>
#include <Adafruit_HMC5883_U.h>
/* Assign a unique ID to this sensor at the same time */
Adafruit_HMC5883_Unified mag = Adafruit_HMC5883_Unified(12345);
void displaySensorDetails(void)
{
sensor_t sensor;
mag.getSensor(&sensor);
Serial.println("------------------------------------");
Serial.print ("Sensor: "); Serial.println(sensor.name);
Serial.print ("Driver Ver: "); Serial.println(sensor.version);
Serial.print ("Unique ID: "); Serial.println(sensor.sensor_id);
Serial.print ("Max Value: "); Serial.print(sensor.max_value); Serial.println(" uT");
Serial.print ("Min Value: "); Serial.print(sensor.min_value); Serial.println(" uT");
Serial.print ("Resolution: "); Serial.print(sensor.resolution); Serial.println(" uT");
Serial.println("------------------------------------");
Serial.println("");
delay(500);
}
void setup(void)
{
Serial.begin(9600);
Serial.println("HMC5883 Magnetometer Test"); Serial.println("");
/* Initialise the sensor */
if(!mag.begin())
{
/* There was a problem detecting the HMC5883 ... check your connections */
Serial.println("Ooops, no HMC5883 detected ... Check your wiring!");
while(1);
}
/* Display some basic information on this sensor */
displaySensorDetails();
}
void loop(void)
{
/* Get a new sensor event */
sensors_event_t event;
mag.getEvent(&event);
/* Display the results (magnetic vector values are in micro-Tesla (uT)) */
Serial.print("X: "); Serial.print(event.magnetic.x); Serial.print(" ");
Serial.print("Y: "); Serial.print(event.magnetic.y); Serial.print(" ");
Serial.print("Z: "); Serial.print(event.magnetic.z); Serial.print(" ");Serial.println("uT");
// Hold the module so that Z is pointing 'up' and you can measure the heading with x&y
// Calculate heading when the magnetometer is level, then correct for signs of axis.
float heading = atan2(event.magnetic.y, event.magnetic.x);
// Once you have your heading, you must then add your 'Declination Angle', which is the 'Error' of the magnetic field in your location.
// Find yours here: http://www.magnetic-declination.com/
// Mine is: -13* 2' W, which is ~13 Degrees, or (which we need) 0.22 radians
// If you cannot find your Declination, comment out these two lines, your compass will be slightly off.
float declinationAngle = 0.22;
heading += declinationAngle;
// Correct for when signs are reversed.
if(heading < 0)
heading += 2*PI;
// Check for wrap due to addition of declination.
if(heading > 2*PI)
heading -= 2*PI;
// Convert radians to degrees for readability.
float headingDegrees = heading * 180/M_PI;
Serial.print("Heading (degrees): "); Serial.println(headingDegrees);
delay(500);
}
and the result in serial monitor is :
HMC5883 Magnetometer Test
------------------------------------
Sensor: HMC5883
Driver Ver: 1
Unique ID: 12345
Max Value: 800.00 uT
Min Value: -800.00 uT
Resolution: 0.20 uT
------------------------------------
then i used this code :
#include <Wire.h>
#include <HMC5883L.h>
HMC5883L compass;
void setup()
{
Serial.begin(9600);
Wire.begin();
compass = HMC5883L();
compass.SetScale(1.3);
compass.SetMeasurementMode(Measurement_Continuous);
}
void loop()
{
MagnetometerRaw raw = compass.ReadRawAxis();
MagnetometerScaled scaled = compass.ReadScaledAxis();
float xHeading = atan2(scaled.YAxis, scaled.XAxis);
if(xHeading < 0) xHeading += 2*PI;
if(xHeading > 2*PI) xHeading -= 2*PI;
float xDegrees = xHeading * 180/M_PI;
Serial.println(xDegrees);
delay (1000);
}
and result in serial monitor is: (i dont move sensor !!!!)
179.30
46.23
141.17
27.48
179.10
0.53
45.96
0.23
0.23
45.86
53.02
26.57
173.09
169.70
0.29
179.93
30.07
and with out attaching sensor it continues !!!!
222.54
178.32
177.21
178.29
179.10
200.85
178.25
219.76
26.73
243.76
178.20
181.94
91.52
178.16
15.15
166.60
2.51
272.55
157.56
150.75
150.57
3.59
45.16
2.97
2.74
2.55
46.89
136.39
45.15
is it working good 
