Compass Calibration procedure

Did I miss a memo? It seems the Compass Calibration procedure has changed?

Edit 12-2016 : Many in the forum pilots say "Dennis Balwin's Way" is the best way to calibrate compass. Also, if having trouble over 915Mhz SiK Radios, try a good USB cable. OK ... now back to the old post.

Now, it's just ... "One strategy for capturing all the white dots is to rotate the vehicle slowly so that each side (front, back, left, right, top and bottom) points down toward the ground for a few seconds."

It's more like the linked video. There is certainly no "dancing" or "chair spinning"in that video.

All I know is that I'm trying to calibrate the compass via 915mhz radios. After trying "compass dance" and "spinning chair method" ... MP errors out before it Auto-Completes. Many white dots are still left.

Best I can tell, after some testing (and multiple tries for a clean compass calibration) the new procedure is very easy.

Initial Setup/ Mandatory Hardware/ Compass/ Live Calibration (at bottom)

Holding the quad in front of you (like it's hovering) ... you slowly rotate it these 3 ways (toward ground), until it's back where it started from.

1. Pitch forward 360 degrees (toward ground). Two complete times (2 revolutions)
2. Roll it 360 degrees (toward ground). Two complete times (2 revolutions)
3. Yaw it 360 degrees (on it's side, like a wheel rolling on the ground). Start with motor(s) pointing directly to ground and Yaw it all the way around. Two complete times (2 revolutions)

Toward the end of step 3, it should beep (auto complete) and give you the Offsets. If it won't complete:

1. Just try again. If done clean--and-fast it seems normal for it to Auto-Complete early, toward end of step 2. If it misses a dot early, it's easier to just reset.
2. Be sure radios aren't too close (resend errors cause dots to not populate properly?).
3. Go slower and turn more perpendicular and carefully. Slightly sway as each major "face" points straight down to earth.
4. Start over and add step 4 below ...

4. Hold it like a cross (instead of X) and pitch-rotate so each motor points to ground. Turn it 90-degrees and do the other 2 motors. Some time during this Step-4, it should Auto-Complete.

It's something real close to this I think. I used the above, got a nice (clean and fast) calibration done (over 915mhz radios with ECC on) and haven't repeated it since. It's been working fine in flight.

Notes:

• It's normal for it to show 2 compasses. It's normal for phantom/un-used Compass-2 to show Error:99.
• This is with AC 3.1.5 and MissionPlanner 1.3.27.
• I think it's better to go outside to do compass calibration. This removes any chance of structure interference during calibration or general compass operation (finding exact North, etc.).
• I leave Auto-Dec on and go outside to calibrate compass. This allows a basic GPS fix and then FC can use Auto-Dec (lookup-table based on GPS). I'm not sure if Declination is used during calibration or not, but maybe it is.
• If inside with no GPS, I temporarily turn-off Auto-Dec and set it manually during compass calibration. However, other benefits of going outside are undeniable.
• My original Compass Calibration notes are in a section here (most still apply). The last time I previously tried to calibrate my compass (months ago) the normal "compass dance" worked fine for me. But not now.
• If compass is set to External, it uses the compass's orientation parameter (COMPASS_ORIENT,0). If set to Internal (COMPASS_EXTERNAL,0) it's ignored (and instead uses the FC's orientation). Pretty sure that is the only difference between them.
• After compass calibration, MP should give you a pretty good indication if your compass is working. Watch heading as you yaw and pitch quad on table. While testing (only), don't power-up with Nova pointing direct North (the FC's default when no compass is attached).
• You only need one good/clean compass calibration done on quad. You don't need to keep re-calibrating it every time you fly or even at a new field or even country. The only time you need to recal is if you re-mount compass due to frame upgrade, crash, or something like that (and then you are back on the work-bench running MissionPlanner anyway). Once the compass is calibrated, you are done. Everyone should leave Auto-Declination Enabled. When you go to any field, you will have a minimal (4-6 satellite) GPS 3D-fix anyway. The flight controller uses this to look-up actual Declination on stored table.
• After compass calibration, you can check quad against a good quality conventional (old-school magnetic) compass. Test in all 4 directions and at various quad pitches. Do not use cell-phone compass. Do not get cell-phone (or similar device) near compass, especially not while calibrating or checking.