Can't get MPU-9250 Sensor to work as compass

Using Arduino Sensors
#1

Hello there!

After several hours of trying to get my MPU-9250 to output it's heading, I thought maybe someone in this forum is able to help me. I am using it with an Arduino Uno R3.

I have tried every MPU-9250 library I found, especially SparkFun's (GitHub - sparkfun/SparkFun_MPU-9250_Breakout_Arduino_Library: Arduino sketch for MPU-9250 9DoF with AH) which is based on kriswiners. I also tried kriswiners library and the Bolderflight library, but never got correct results. The heading is sometimes negative, never over 180°, and so on... I have calibrated it with a figure 8 movement several times, still, no correct results.

Is there any good tutorial I could follow? All I want is the compass heading, nothing else.

Would greatly appreciate any help!

#2

You need to properly calibrate the magnetometer for it to work at all. After that, the code is pretty simple, no library needed.

heading = atan2(mag_y, mag_x)*180./PI; //in degrees, magnetometer held level, Z straight down.

Here is an overview of the calibration process.

#3

It seems like the SparkFun program also does a calibration process in the beginning, but my heading is always negative, so is that calibration just not good enough?

#4

Correct.

#5