Firstly a huge thanks to the AC3 dev team, I'm really excited about this version. The Dev's are also putting in long hours and responding quickly to all the questions posted, a superb effort.
I built my Tarot T810 hexa (I was busy with a build log but got carried away with the build, I'll update soon) and took it out for some initial hovering today.
I connected the APM 2.5 via USB to download the log in order to check vibrations, and noticed that the compass was moving around (by as much as 30 degrees, even more). I then reconnected the batteries and the compass was still moving around, but once I armed the copter the compass stabilized a bit, but still moving around?
Attached is the TLOG, I was wondering what would cause this, as there was no power to the ESC's while connecting to USB, so no mag field interference? On a side note, I did compassmot with an Attopilot current meter attached, but ended up blowing the current meter when i reconnected it wrong way round :( - these log are without a current sensor attached, maybe this could cause issues?
Below is the mag field on USB
Here is the mag field in a hover.