HMC5883L - wie bekomme ich vernünftige Kursanzeigen?

/*

 Uses HMC5883L to get earths magnetic field in x,y and z axis 

 Displays direction as angle between 0 and 359 degrees

*/

#include <Wire.h> //I2C Arduino Library

const int hmc5883Address = 0x1E; //0011110b, I2C 7bit address of HMC5883

const byte hmc5883ModeRegister      = 0x02;

const byte hmcContinuousMode        = 0x00;

const byte hmcDataOutputXMSBAddress = 0x03;

void setup(){

  //Initialize Serial and I2C communications

  Serial.begin(9600);

  Wire.begin();

  //Put the HMC5883 IC into the correct operating mode

  Wire.beginTransmission(hmc5883Address); //open communication with HMC5883

  Wire.write(hmc5883ModeRegister); //select mode register

  Wire.write(hmcContinuousMode);   //continuous measurement mode

  Wire.endTransmission();

}

void loop(){

  int x,y,z; //triple axis data

  //Tell the HMC5883 where to begin reading data

  Wire.beginTransmission(hmc5883Address);

  Wire.write(hmcDataOutputXMSBAddress); //select register 3, X MSB register

  Wire.endTransmission();

 //Read data from each axis, 2 registers per axis

  Wire.requestFrom(hmc5883Address, 6);

  if(6<=Wire.available()){

    x = Wire.read()<<8; //X msb

    x |= Wire.read(); //X lsb

    z = Wire.read()<<8; //Z msb

    z |= Wire.read(); //Z lsb

    y = Wire.read()<<8; //Y msb

    y |= Wire.read(); //Y lsb

  }

  //Print out values of each axis

  Serial.print("x: ");

  Serial.print(x);

  Serial.print("  y: ");

  Serial.print(y);

  Serial.print("  z: ");

  Serial.print(z);

  int angle = atan2(-y , x) / M_PI * 180; // angle is atan(-y/x)

  if(angle < 0)

     angle = angle  + 360; // angle from 0 to 359 instead of plus/minus 180

  Serial.print(" Direction = ");

  Serial.println(angle);

  delay(250);

}