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DeveloperPermalink Reply by Randy on July 21, 2011 at 12:07am

to compare the arducopter compass and the regular compass, you should set the declination to zero in the CLI.  If you don't do this, the ardu mag will show you true north instead of mag north (true north is important for position hold).

 

the other difference between the two will be the offsets.  If you haven't flown your quad yet, the offsets will be all zero and this will lead to some inaccuracy in the headings returned by the ardu mag.  If you fly it (or wave it around in the air for more than 4 minutes), the offsets should be updated and saved to eeprom (you can check via the CLi).

 

after all that I'd expect they'd be pretty close but even then 5 degrees of difference isn't much...we only need it to be accurate enough to stop yaw drift and work for position hold.

 

 

 

 

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Permalink Reply by brett binnekade on July 21, 2011 at 12:30am

Oh yes that actually makes sense now, setting the declination to zero.

 

Once you put the declination in then the quad should point to true North.

 

got another quick question regarding the image below.

I cant show the values as I dont have my quad with me to plug in.

somewhere in the place that I have marked in red is a value called Magnetic_DEC or something like that.

What is this value for? Mine was showing 0.309 which is not my magnetic declination of 17,44.

 

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DeveloperPermalink Reply by Randy on July 21, 2011 at 12:44am

It's a guess but i might be that it's the declination shown in radians.  17.44 degrees = 0.304 radians.

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Permalink Reply by brett binnekade on July 21, 2011 at 4:01am

good quess=) I think you may be right! can anyone clarify?

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