hmc5883l outputting random degrees

Other Hardware Sensors
1

Hello,

I have recently bought a GY-271 HMC5883L compass sensor for use in my robot car.
Link to the product is here: link to product

Now I want to test the sensor without putting it in my robot car first to know that it works, but I can't seem to get it working.

I followed this tutorial to try and get it to work: link to article

My connections are like this:

  • VCC to arduino 5v
  • GND to arduino gnd
  • SDA to arduino A4
  • SCL to arduino A5

and this is the code I uploaded to the Arduino Uno like it says in the tutorial:

#include <Wire.h>
// Reference the HMC5883L Compass Library
#include <HMC5883L.h>
 
// Store our compass as a variable.
HMC5883L compass;
// Record any errors that may occur in the compass.
int error = 0;
int ledpin = 13;
// Out setup routine, here we will configure the microcontroller and compass.
void setup()
{
  // Initialize the serial port.
  Serial.begin(9600);
pinMode(ledpin, OUTPUT);
  Serial.println("Starting the I2C interface.");
  Wire.begin(); // Start the I2C interface.
 
  Serial.println("Constructing new HMC5883L");
  compass = HMC5883L(); // Construct a new HMC5883 compass.
    
  Serial.println("Setting scale to +/- 1.3 Ga");
  error = compass.SetScale(1.3); // Set the scale of the compass.
  if(error != 0) // If there is an error, print it out.
    Serial.println(compass.GetErrorText(error));
  
  Serial.println("Setting measurement mode to continous.");
  error = compass.SetMeasurementMode(Measurement_Continuous); // Set the measurement mode to Continuous
  if(error != 0) // If there is an error, print it out.
    Serial.println(compass.GetErrorText(error));
}
 
// Our main program loop.
void loop()
{
  // Retrive the raw values from the compass (not scaled).
  MagnetometerRaw raw = compass.ReadRawAxis();
  // Retrived the scaled values from the compass (scaled to the configured scale).
  MagnetometerScaled scaled = compass.ReadScaledAxis();
  
  // Values are accessed like so:
  int MilliGauss_OnThe_XAxis = scaled.XAxis;// (or YAxis, or ZAxis)
 
  // Calculate heading when the magnetometer is level, then correct for signs of axis.
  float heading = atan2(scaled.YAxis, scaled.XAxis);
  
  // 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: 2� 37' W, which is 2.617 Degrees, or (which we need) 0.0456752665 radians, I will use 0.0457
  // If you cannot find your Declination, comment out these two lines, your compass will be slightly off.
  float declinationAngle = 0.0457;
  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; 
 
  // Output the data via the serial port.
  Output(raw, scaled, heading, headingDegrees);
 
  // Normally we would delay the application by 66ms to allow the loop
  // to run at 15Hz (default bandwidth for the HMC5883L).
  // However since we have a long serial out (104ms at 9600) we will let
  // it run at its natural speed.
  //delay(66);
}
 
// Output the data down the serial port.
void Output(MagnetometerRaw raw, MagnetometerScaled scaled, float heading, float headingDegrees)
{
   //Serial.print("Raw:\t");
   //Serial.print(raw.XAxis);
   //Serial.print("   ");   
   //Serial.print(raw.YAxis);
   //Serial.print("   ");   
   //Serial.print(raw.ZAxis);
   //Serial.print("   \tScaled:\t");
   
   //Serial.print(scaled.XAxis);
   //Serial.print("   ");   
   //Serial.print(scaled.YAxis);
   //Serial.print("   ");   
   //Serial.print(scaled.ZAxis);
 
   //Serial.print("   \tHeading:\t");
   //Serial.print(heading);
   //Serial.print(" Radians   \t");
   Serial.print(headingDegrees);
   Serial.println(" Degrees   \t");
  //delay(1000);
  if((headingDegrees >=1)&(headingDegrees <= 45)  )
  digitalWrite(ledpin,HIGH);
  else 
  digitalWrite(ledpin,LOW);
}

I commented out the unnecessary lines at the bottom because my goal is to only get the degrees of the compass, but even with the lines uncommented it still doesn't work.

All the libraries used are correctly imported.

This is what I am receiving in the serial monitor when running the code:

1499×684 11.2 KB

The same three degrees keep showing.

Now I am completely lost here.
I've tried several tutorials but I keep getting the same problem.
If anyone could help thanks in advance.

arduino_HMC5883L_sensor_problem.PNG
arduino_HMC5883L_sensor_problem.PNG1499×684 11.2 KB

2

I would first test with a mechanical compass to see whether there is any local interference. There still might be, a mechanical compass is likely less sensitive.

Then use a magnet close to the sensor to create a magnetic field that overpowers all local sources to test whether there is something wrong with the sensor handling.

Another test would be to run the Arduino from a battery and away from your computer. Use a little LCD to display the data. My laptop makes my mechanical compass crazy.