Find the heading using magnetometer BMX055

Other Hardware Sensors
1

Hi guys,
I have played with the BMX055 sensor from Bosch. I want to find the heading of the system using the integrated magnetometer but I can not find the heading of the system.
I have tried using below equation but it did not work.

Heading = atan2(Y_magnetometer, X_magnetometer) * 180 / PI;

the code for reading the magnetometer data:

// Addr_Mag 0x13 
void BMX055_Mag()
{
  int data[8];
  for (int i = 0; i < 8; i++)
  {
    Wire.beginTransmission(Addr_Mag);
    Wire.write((0x42 + i));    // Select data register
    Wire.endTransmission();
    Wire.requestFrom(Addr_Mag, 1);    // Request 1 byte of data
    // Read 6 bytes of data
    // xMag lsb, xMag msb, yMag lsb, yMag msb, zMag lsb, zMag msb
    if (Wire.available() == 1)
      data[i] = Wire.read();
  }
  // Convert the data
  xMag = ((data[1] <<8) | data[0])>>3;
  if (xMag > 4095)  xMag -= 8192;
  yMag = ((data[3] <<8) | data[2])>>3;
  if (yMag > 4095)  yMag -= 8192;
  zMag = ((data[5] <<8) | data[4])>>1;
  if (zMag > 16383)  zMag -= 32768;
}

My question is:

  1. Is there any problem with my provided code?
  2. How to calculate the heading using a magnetometer?
    Thank you for your help,
2

Magnetometers do not work "out of the box" and need to be calibrated. The most comprehensive tutorial on calibration is Tutorial: How to calibrate a compass (and accelerometer) with Arduino | Underwater Arduino Data Loggers, but you can find simpler approaches on line that will give approximate directions.

If you want help with code, post ALL of it. Snippets are useless.

3

Thank you for your reply,
That is a helpful link. I will read through the suggestion link and calibrate the magnetometer. I will post the result when I succeed.

4

This topic was automatically closed 120 days after the last reply. New replies are no longer allowed.