Arduino Forum

Using Arduino => Sensors => Topic started by: Kaizen_Inventor on Oct 16, 2019, 05:15 pm

Title: Selecting Magnetometer
Post by: Kaizen_Inventor on Oct 16, 2019, 05:15 pm
Hi there,
I am working on project which requires a Magnetometer Sensor. Because I am in need of precise and accurate data for calculation , I am confused that which board should I select and there are many out there.

Thanks in advance.
Title: Re: Selecting Magnetometer
Post by: jremington on Oct 16, 2019, 06:26 pm
Please define "precise and accurate", using numbers with units of measurement, and state your budget.

For sensors, avoid eBay junk. The more you spend, the higher the quality.
Title: Re: Selecting Magnetometer
Post by: Idahowalker on Oct 16, 2019, 10:30 pm
To narrow down the field you might limit your selection to those magnetometers that use the SPI buss. Communication bottlenecks may, at some point, become an issue.
Title: Re: Selecting Magnetometer
Post by: MarkT on Oct 16, 2019, 11:32 pm
Precise and accurate isn't really what a MEMS magnetometer will give you I'm afraid, they are micro-miniature
and that means compromize on specifications.

But what do you mean by "precise" and "accurate"?  What maximum flux density do you need?
Title: Re: Selecting Magnetometer
Post by: Kaizen_Inventor on Oct 17, 2019, 04:50 pm
I am not sure about magnetic flux,

Actually , I am trying make my telescope system and for that I need to known the direction I am pointing. Hence, I thought that I could use magnetometer as a compass to figure it out.

But the magnetometer I used HCM5883I didn't offer me a constant output, the data I received was fluctuating.

And because small variation in data can mess up the system I needed a accurate magnetometer and realiable too.

In this context I was using the words precise and accurate.

Thanks you in advance
Title: Re: Selecting Magnetometer
Post by: jremington on Oct 17, 2019, 05:05 pm
A MEMS magnetometer like the HMC5883L (no longer manufactured, by the way, most sold as such these days are actually mislabeled QMC5883) need to be carefully calibrated to work as compasses, and at best, you will get perhaps +/- 1 degree accuracy.

If that is good enough, buy a more modern compass module from Pololu and follow this tutorial to calibrate it: https://thecavepearlproject.org/2015/05/22/calibrating-any-compass-or-accelerometer-for-arduino/ (https://thecavepearlproject.org/2015/05/22/calibrating-any-compass-or-accelerometer-for-arduino/).