Bit of a technical support call this one.
I've got one of these:
http://www.goodluckbuy.com/ublox-neo-7m-gps-module-10hz-with-compass-for-apm-flight-controller.html
attached to an apm 35x35 (http://www.goodluckbuy.com/miniapm-v3-1-mini-ardupilot-mega-2-6-external-compass-apm-flight-controller-for-multicopter-fpv.html).
I've got it all running, apart from the compass. When I try to calibrate, it only has data points on one axis of the calibration screen "ball" and never actually completes - keeps saying it's missing data points.. I end up with crazy offsets, like 10000, 75000,14000 and the compass doesn't work. GPS works fine. Unit itself worked ok on another quad. I've tried swapping the cables over, but then it fails to do anything at all - it collects 4 data points, then fails to collect anymore.
What have I done wrong?
Replies
Hello
look at them here: http://www.rcgroups.com/forums/showthread.php?t=2182722
I haven't finished my build yet but i'm using the same APM mini and discovered that it does in actual fact have an onboard compass despite claiming to be a 2.6 revision. On mine JP1 was shorted out of the box so you may have a case of conflicting compasses. If you're only moving the external compass maybe the internal compass, being static, is muddling the calibration.
HTH
Chris
The GPS/compass module you bought: are you sure it is not a bad Chinese clone; I would not be too sure about sourcing from this kind of web site.
Have you tried another GPS/compass module (one from 3dr that you know for sure is working), to exclude a problem with this mini APM Chinese cheapo?
Have you tried to use Ublox center to load the GPS/compass module with the 3dr parameters file?
Are you rotating the craft around all it's axis when you calibrate it?
However, when calbrating I'm only moving the compass, not the quad. Does that matter?
YES, it does. That is the whole point to compass calibration. The calibration essentially identifies metallic items in your airframe like bolts, fasteners, wiring, battery, etc and allows the copter to compensate for that when trying to navigate in the larger magnetic field of the earth.
yup.