Pixhawk 2.1 / GPS Here setup and calibrations

Good afternoon,

i just acquired a Pixhawk 2.1 with a GPS module “Here” ( bundle available at Skyetech, great serice by the way ) .

I was used to Pixhawk 1 and i must admit i am a bit lost regarding the Compass / GPS setup on this little guy despite searching on the forum.

Here are a coupe of questions, i would be more than happy to compile the infos i can gather here to complete the available PDF from Hex regarding initial setup…

  1. In mission planner (1.3.46) , i installed the beta firmware 3.5 RC4 ( 3.4.6 gave me gyro errors messages) for a quad ( will be the flying guinea pig…)

  2. On the Compass settings, should we select Pixhawk/PX4 or APM with external compass ? I selected PX4. Would be neat to have a simple option " PX2.1 with GPS here" … Compass 1 is setup on " none" regarding orientation mounting by default.

  3. In general compass settings, ok we sure have the comapss 1 as external compass, so i guess we have compass 2 and 3 as internal but here is the thing : i did a calibration with the unit umounted on a frame so GPS “Here” was not attached to the PX2.1 , and the bigger offset i get is on… compass 2 ?? I thought i would get it on compass 1 ( crazy offset) and have close offsets values on compass 2 and 3 as they would be supposed to be built on the same hardware part ( PX2.1) … If someone can enlight my candle, thank you in advance .

  4. So here are my actual settings :

Flight controler type : Pixhawk / PX4
Compass (General) : enabled, primary compass :1, automatic declination
Compass 1: Enabled and none for orientation, externaly mounted
Compass 2 : Enabled
Compass 3: Enabled

I also have a very noob question : When i use the graphs for tuning, and select Mag Field 1, 2 and 3, the magfield 1 and 3 are same direction, but magfield 2 is inverted with magfield 3 on the roll ( same on tilt) ??. I could understand magfield 1 would be inverted ( wrong orientation or mounting) but 2 and 3 ? What would i be missing here ? For me it would mean that compass 2 and 3 ( onboard) would be mounted on up and one down on the PCB , would it be possible that the mags are built ( hardware) one facing up and one facing down and that it would be needed to trick the thing by setting compass 2 as externalwith a roll 180 orientation installation? Sorry for the noob question, for me it would be like compass 2 and 3 fight together most of time so true readings are from compass 1 (external on GPS Here antenna ) and 3 ?

Thank you for any input,

Hi, any idea anmody please ? :slight_smile:
Or is it just htat it’s needed to use only one compass ( internal) + external only ?
Thanks a lot forany information,

The internal compass variances differ greatly.
It is even recommended not to use internal compasses.
At any one time the Arducopter code only uses one compass.
The other compasses are there as a fall back.
On our installations I fir 2 external compasses and have only the best internal active as a fall back.

Thank you very much for your answer,

Yes, variance is great, i confirm that…

I will get a second compass ( external) unit and setup all this little world to see how it goes,

Thank you again,