I have an apm2.5 with a cheap Chinese neo-6 ublox + compass V 2.0 board
and have been having problems in auto mode and circle.
on investigation i found that the mission planer compass display was very non liner
compared to the actual heading several re calibrations were tried some better some worse
on looking at the board i noticed that there is rechargeable battery underneath the magnetometer chip
so i unsoldered this battery, re calibrated and all non linearity disappeared !! ( and low offsets)
placing the battery near the chip pulled the indication way off
lesson learned (again) Don't Bye Chinese Clones!!
So if you are having strange bhaveyer in auto modes and have this v2.0 board
throw it away and get a real one
Yes i agree with your comments,
My point is that the board is poorly designed with a magnetic battery( no current flowing )
on the underside of the board overlapping the mag chip.
why start out with a built in handicap like this ?.
also current flowing (therefor mag field) presumably changes during charging ?
Sorry I didn't make it clear that the battery i am taking about is the gps backup battery which allows the saveing of information in the ublox module, and is part of the gps board,
Its odd that is made from magnetic materials?
It affects the mag chip even when disconnected
further experiment revels that calibration techniques seem to alter calibration
( best seems to be level rotate about earth vertical axis, nose up rotate about earth vertical axis,nose left rotate about earth vetical axis,nose right rotate about earth vetical axis ,nose down rotate about earth vertical axis, inverted rotate about earth vertical axis,)
Perhaps some one could clarify the correct technique ?
I am going to relocate the battery to the opposite corner of the board where it seems to not interfere with the mag chip and gives lowest offsets -80, 20, 25,.
I now get + - 2 degs accuracy which i think is pretty good
That is good enough for sure. Better than most compasses.
hi to all
I bought a not so cheap GPS + compass from witespyquad (http://witespyquad.gostorego.com/flight-controllers/ublox-6m-gps-w-...) and I get a horrible compass calibrations with apm 2.6. Values > 300. The Quad fly well but I dont not like so high values and mission planner is still waiting more data after >2000 points.
I just put a 3dr module and mission planner send me 80, 8, 40 after 500 points calibrations.
It is right that the huge battery is pasted under the compass. I put off the battery but values seem to stay aroud 300.
Any idea ?
Thank you !
This looks like the same board as mine.
settings roll 0 orietation 0
on mission planer look at the compass direction with and without the battery (just hold it in place by hand)
To see if makes any difference.
mine caused an error of 80 +. degs?
If I understand well, there is no need to move the battery BUT we have to follow your rotate way ?
I get it ! Put off the GPS, put it on the back
simple but I get offset of 50...