Okay - I am getting very frustrated here - I thought I was having trouble with my sparkfun magneto so I ordered a DIY - Only to have the same problem - Last flight I was unable to use CLI to determine my offsets - The last number always stays -2048 no matter how I turn it -


Little more info - My compass offsets used to be as follows: 395, -85, 11.5
Now they are reading 395, 187, -2048
If I move the magneto around there is no change in these numbers - Thanks guys

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     You're saying that you're also seeing -2048 for the 3rd (the Z) value coming back from your magnetometer?


     It sounds very much to me like a broken mag in your case.  The tapping on the mag board sounds like it's causing a reset of the mag board.  So I think a new mag will fix the problem.

Yep, see my thread here: http://diydrones.com/forum/topics/another-magnetometer-question?xg_...
Except it's also intermittently just returning zeroes, or freezing on a set of readings. I just redid all the solder connections to it and it's still acting up.

Mine was no Mag error - It did exactly the same thing with a brand new mag - One was a sparkfun one was a DIY - One did exactly the same thing on 2 different APM's as well- Has to be the oilpan or a faulty new mag - But this board is also a foxtrap - they have been plagued with problems -





My magnetometer shows this reading. Should i buy new 1??


     definitely your mag isn't working.  It could be a number of things.  Have you double checked that you wired it up correctly according to the wiki?


Hi Randy,


Thanks for reply. Im using drones mag connected using cable. My mag works nice before a small crash. Is there anyway to check a fried mag???





I watched your test video...
I too have had some weird trouble like yours while doing bench testing.
Hopefully what I discovered may be helpful.

After investigating I found that the 5 volt power on the APM system was dropping to low when servos were connected when using the usb port, causing a reset or brown out.

I connected my power supply to the APM power input and I found that the servos, even with no mechanical load, could cause the current to exceed 2 amps briefly.
With the USB connected and a RX NiCad battery pack connected to the receiver to supply extra power for the servos, the problem almost went away... As the battery pack voltage dropped the problem reappeared.

So, I de-soldered the jumper that connects APM board power to the positive on the servo connectors.
Problem gone.

Thanks Chris - I did not have anything connected and it was still doing it just sitting here




Hi Michael,

A somewhat non related question about compass drift/accuracy. You mentioned you have been flying for months using the compass. Do you have any comments on noticeable drift in flight ? Or even bench testing ?  I would also assume you run through a calibration step at start up ? Maybe not since for steering the absolute heading isn't a real issue ? Have you noticed any non linear regions in the compass swing ?


My questions are driven by an expected application that would need compass accuracy to about 5 degrees over several hours of operation.





     I think it depends upon he environment you're flying in mostly rather than this particular compass.  As i'm sure you know, there's no 'drift' like a gyro of course but if you're testing in your house or outdoors in an urban environment there are magnetic disturbances all over the place and these throw off all compasses including these magnetometers.


     The requirement for 5 degrees of accurancy is not that difficult nor is several hours of operation.



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