Inaccurate heading from Qwiic Micro Magnetometer - MMC5983MA

Sensors IMU & Motion
1

I bought 2 and I think I’m having trouble with both. 1 definite problem with one, and a possible problem with the other.

My setup: Arduino IDE → I2C Digital Compass example → RedBoard Qwiic → Qwiic cable → Qwiic Micro Magnetometer - MMC5983MA

1st problem, maybe a redboard problem:

Readings are hovering around one of 3 positions.

Here’s a snippet of the readout from the serial monitor in Arduino IDE:

Heading: 132.9

Heading: 132.9

Heading: 132.8

Heading: 132.8

Heading: 132.8

Heading: 132.7

Heading: 151.1

Heading: 150.9

Heading: 150.7

Heading: 150.9

No matter what direction I point, it will be one of these 2 positions, or sometimes about 118.

Strangely, the problem does not occur on my other RedBoard, but both boards and both magnetometers are new.

Second problem (with a different magnetometer) / maybe not a problem?:

Running the Digital Compass example in Arduino IDE, When I point North, I see approx 360 degrees, but when I point the opposite direction (what I would assume to be South) I get about 220 degrees. I.e. North and South do not appear to be opposite. However, when I point at 180 degrees according to the magnetometer, and then 270 degrees, it is almost a perfect right angle (measured on paper).

Any help would be appreciated! Thanks :smiley:

2

Magnetometers don’t work out of the box as a compass, and need to be calibrated.

Simple tutorial: https://diydrones.com/profiles/blogs/ad … or-dummies

Best overview and advanced guide: https://thecavepearlproject.org/2015/05 … r-arduino/

3

I was working my way through these tutorials, but had no success. Are you sure this method works for the MMC5983MA? Is there something I need to do for this to work with the MMC5983MA? If you are sure the tutorial is sufficient I will continue trying to work it out :slight_smile:

The Arduino sketch mentioned in the Simple tutorial doesn’t seem to do anything or create any output in the Arduino IDE serial monitor for my RedBoard Qwiic.

4

The methods described work for any magnetometer.

Use Serial.print() to output raw measurements on the Arduino serial monitor (or use a terminal program to log them to a file) and process the data with other programs.

See this forum post for more examples: https://forum.pololu.com/t/correcting-t … eter/14315