Hi all,

I built a 4inch LR quad and put the Matek S8M-5883 GPS+Compass on it. I’m trying to make sure i have the alignment right for the compass as it is currently not performing as expected. Today I locked 8 satellites, took off and went straight ahead of me about 300m and activated GPS return to home and the quad pointed directly away from me and kept flying.

The mateksys website says that standard setup (i.e., FC pointing forward and compass pointing forward) is CW270 Flip. My set up is different with both of them actually pointing backward and the GPS unit at a bit of a downward angle so when the quad tilts forward it will point more up. See very badly drawn schematic here:



I have it set to CW270 (since they are both still pointing in the same direction, I thought that would be the right setting). But I changed the mag_align_pitch from 180 to 135 (to account for the 45 degree pitch angle it is on). I have the use magnetometer on RTH turned on.

Does this seem right? Should it be 225 on pitch? Should the yaw be different? Is there something else altogether I’m missing? I’m not actually going medium or long range until i’m really confident that this unit will perform as expected and for some reason can’t figure this part out!

Thank you!

I think you want mag alignment set to CW90 Flip in that case. Not sure if the mag align pitch setting is important, but what you have it set to sounds correct.

Hi V-22, I think the yaw setting (the CW270 vs 90) is relative to the FC and assumes the FC and the GPS are facing forward. If I flip both to face back, aren’t they still the same relative to each other, so still CW270?

(23-Dec-2020, 02:14 AM)clone2002 Wrote: Hi V-22, I think the yaw setting (the CW270 vs 90) is relative to the FC and assumes the FC and the GPS are facing forward. If I flip both to face back, aren’t they still the same relative to each other, so still CW270?

I 'm pretty sure it's relative to the craft. You need to tell the FC which direction is forward so it knows what the gyro orientation is, and you need to tell the magnetometer what direction is forward so it knows what direction the craft is facing.

Hmm, I tried that, CW90 flip didn't seem to work. Honestly both of them (CW90FLIP and CW270FLIP) kind of work if I angle the craft forward so the magnetometer is flat, but then the compass on BetaFlight just spins back to north (or south depending on which of the above i do), and can sort of lock on that but other directions don't seem to work. Argh, very frustrating!

also this is what Matek says on their site: "Compass Alignment(Arrow forward and flat mounting), INAV/BetaFLight: CW 270° Flip when flight controller arrow is facing forward also"

At the bottom of this page in "Tips"
http://www.mateksys.com/?portfolio=m8q-5883

I had issue with getting the exact compass to work. It seems to take a minute or two to start reading the right heading. Try letting the gps unit warm up for a few minutes outside with nothing overhead. Using your phone compass find north. Place quad facing north and read the OSD. If it’s north your done, move quad in all directions noting your phone compass corresponds. If it’s not right, don’t unplug the Lipo but get into BF and change degrees then set quad back outside. Do this until it reads north.  Don’t have your props on! You should be getting a lot more than 8 satellites usually I’m getting 16-17. Make sure your VTX is putting out the lowest power so you don’t overheat it. I found it just works better if I let the quad stay powered during the time adjusting compass degrees in BF. Not sure why either kinda a noob myself maybe it’s just my set up.

Maybe try cw135 flip. 1/2 of 270, or 180? I have all of my mateks w arrow facing forward using the 270. i'm not sure the angle makes much of a difference but the rotation will, the one i just built is at approx 45 deg angle and it points north just like my analog compass.

i settup "rescuemode" a few times, is there also "return to home"?
i dont know a compass configuration, i cant help. i only like to suggest "home arrow"-osd feature. i used it to check the functionality of the 3d-fix befor try rescuemode by a switch, but probably the suggestion doesnt match the problem on a compass....

Thanks everyone, I think I largely got it working. I think I had interference from my crossfire antenna which i mounted too close to the unit. I moved it away and think that largely took care of it. For me 90 degrees worked and i set mag pitch to 160 degrees instead of 180 (new mount is about 20 degrees angled). So far it seems ok, but if anything changes will let you know!

Do you get more satellites now?

(25-Dec-2020, 08:18 AM)Kevin2112 Wrote: Do you get more satellites now?

I never had an issue with satellites, it’s just that 8 is my minimum for setting home. But usually get between 13-20 once flying. The main issue was the compass alignment. For now the arrow home works well and it seems to know where it’s going if I trigger RTH (I have mag on for RTH). I’m flying with DJI and not all the OSD elements are visible, so I don’t see the compass bar to check but things seem to be working as they should!

Good to know you got it working. I don’t trust mine enough to switch rescue mode on.