Apm 2.8 internal/external compass issues

Message subject: Re:hoping you can help with this situationFolder: Inbox
If you could ask this question on the forum I’ll do my best to answer. If it’s asked on the forum it benefits others who may have the same question. If you have asked the question send me link and I’ll take a look. Thanks. Bill

Sent: Sun Nov 08, 2015 5:46 pm View message | Post a reply
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Message subject: Re:hoping you can help with this situationFolder: Sent messages
Thanks for responding. Let me ask you this. If I rotate the ublox gps/compass module 180 degrees while the apm board remains stationary, should the software not recognize this rotation as if the copter is turning 180 degrees. Currently, when I do this, the software does not react in any way when I rotate the compass module.
If I rotate the apm 180 degrees but leave the gps/compass module stationary, apm planner recognizes that the copter has turned 180 degrees.

Or, were you trying to explain to me that when the module is connected to the apm, it registers the movement of the apm board as a sort of proxy for the compass module itself.

Also, even without the compass module attached, the board transmits compass data. Wasn’t the 2.8 supposed to be without an internal compass? It is an authentic 3dr board that has 2.8 printed on it. Should I try to get the retailer that sold me the board to exchange it for an apm 2.8 that is truly without a compass?

I was planning on using this board for my new tarot 650 build. It being the first quad I have built of significant expense, I really just wanna be confident the board is going to perform as expected before risking my new setup.

Sent: Sun Nov 08, 2015 5:22 pm View message
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Message subject: Re:hoping you can help with this situationFolder: Inbox
The APM2.x cannot distinguish if the compass is onboard or external. It has the same id. Even though it’s externally connected, it reports the same as though it was onboard. This is why when using APM2.5 HW you need to cut the compass pcb track to disable the onboard one. As for 2.8HW I don’t know the specifics, but if it’s not there, it should just work.

Sent: Sun Nov 08, 2015 12:16 pm View message | Post a reply
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Message subject: hoping you can help with this situationFolder: Sent messages
Hi Bill. You have been very helpful in the past so I thought I’d send you a pm and see if you might be able to shed some light on an issue that I’m having with a new APM 2.8 board.
1st issue is that I was under the impression that the 2.8 does not have an onboard compass. I plugged it in to apm planner via usb connection as soon as I opened the package and I was surprised to see that it was transmitting compass data to apm planner. I went connected my external ublox neo8mn to the unit and went into the initial setup tab. I did tyne accelerometer calibration and in the compass tab I selected the option,“apm with 3dr gps/compass”. I went ahead with the live calibration, which seemed to be successful. So, I exited the setup tab and opened the flight data tab. At this point I noticed that the compass data was still coming from the apm 2.8 internal compass. Gps 3d fix and sats available were all good, but the compass being recognized by APM planner was not the external compass. I opened the config/tuning tab> advanced parameters_
These are the settings that that I found there;
COMPASS is attached via external cable
primary compass> first compass
compass 2> disabled
compass 3>disabled

I’m assuming the reason that I can’t get my board configured for the external compass has something to do wight hose settings mentioned above or it is related to the new jumpers on the 2.8 tha weren’t present on the 2.6. If you know how to config for external compass on the APM 2.8 and wouldn’t mind sharing your knowledge, I’d greatly appreciate it.
Jon Grace

Sent: Sun Nov 08, 2015 11:07 am View message

The compass indicator in the PFD on APM Planner 2.0 is the heading of the vehicle. This is not the compass and is based on yaw for copter. (See MAVLink message VFR_HUD)

The actual output of the compass can be view in the MavLink Inspector widget. There you should see the behaviour you are expecting. message is in MAVLINK_MSG_ID_RAW_IMU

thanks bill