Crius AIO Pro V2.0 magnetometer variations

brewski · Post by **brewski** » Thu May 22, 2014 9:40 am

Hi Guys,
Just installed my new Crius AIO Pro V2.0 last night, updated the installed V2.2 to 2.3, calibrated sensors/TX & took for a flight today. Only small TX adjustments in Accro & no ACC adjustments needed in Angle/Horizon for stable hover. I noticed A big improvement in Baro enabled with the high res Barometer on this board compared to to the Crius SE 328 BM058 sensor. Quad will hold within approx. 300mm..superb!

I then tried enabling Headfree mode & it wandered depending on throttle. I connected to PC & observed the readings with throttle & saw changes of up to 30degrees!
Being an electronics engineer this makes sense with high current distribution board 10 millimetres below FC.
The magnetic fields generated in the distribution board and cables is quite small but the magnetometer is only detecting very low (in comparison) magnetic fields of the earth.

I will be installing a magnetic shield between distribution board & fc. Ideally .2mm steel or stainless steel will do the job, but possibly other metals could be used.
If you doubt try run GUI & bring a small magnet near FC & see the result.
We shield the barometer from propwash & sunlight but don't consider the heavy current flowing in power distribution board, which in many designs is in close proximity to FC.

Anyone else noticed this issue?

Cheers..B

waltr · Post by **waltr** » Thu May 22, 2014 3:38 pm

This is a very common issue and has been noted many times.
No one has been able to shield the magnetometer so I would like to hear your results.

The common solution that does work is to move the magnetometer far away from the battery/motor leads. This is why many of the GPS modules also have a magnetometer and they are mounted on a stalk.

OrbitCowboy · Post by **OrbitCowboy** » Fri May 30, 2014 1:44 am

My current quad has a Q-brain 25A x4 ESC, just below the 328p FCB. I wonder whether using the perforated material used in the doors of microwave ovens would isolate the power distribution board from the FCB.

brewski · Post by **brewski** » Fri May 30, 2014 9:07 am

Hi OrbitC,

I tried some perforated thin steel as carpenters use to joint wood. This only resulted in about 5 degree improvement. It initially threw mag out about 20deg from residual field so I had to do a recal with plate installed. Thinking seriously about removing mag IC from FC & connecting it with ribbon cable. I could then mount it on stalk with GPS antenna as I've seen on some commercial quads. Others mount mag chip low on rear leg. A bypass ceramic capacitor would need to be fitted on IC power pins & possibly shielded cable may be required.
I'll write it up on forum if I go ahead & it works when I get time.
Another (easier & less destructive) solution is to disable mag on board & use external I2C mag board. These can also be purchased with GPS antenna on same board.
Cheers..B

OrbitCowboy · Post by **OrbitCowboy** » Fri May 30, 2014 11:35 am

@brewski

Too advanced for me ... once I find that heading hold isn't working maybe I'll try a section of space blanket or something.

-- OC

brewski · Post by **brewski** » Sat May 31, 2014 12:20 am

Space blanket is only aluminium foil so will do nothing. You need something that can block magnetic fields.
I am next going to try twisting all high current carrying cables as this cancels the field they generate.

PirateFly · Post by **PirateFly** » Sat Aug 02, 2014 12:25 am

Hey Brewski,

I know this thread is a few month old, but I was just wondering if you had any success with the onboard magnetometer?

Thanks
-J

brewski · Post by **brewski** » Sat Aug 02, 2014 2:18 am

Hi PirateFly,

I got it a lot better by twisting the heavy current leads from distribution board & raising FC 20mm . Metal shield in between helped by about 10 deg but still not happy.

On Crius AIOP V2 it is very easy to disconnect onboard Mag, just cut links on J2 & J3.
You then modify the MW 2.3 Navi b7 def.h (not config.h).
Under #if defined Crius_aiop_pro_V2_v1 uncomment (//) out line-
#define MPU6050 _12C _AUX_MASTER //MAG
Save & then upload to your FC.

I mounted ext Mag board on CF square tube out front of quad & now have no deviation with any throttle setting.

eatkabab · Post by **eatkabab** » Mon Sep 15, 2014 5:21 pm

I too have this mag issue on my Naze32 but that issue cannot be solved easily. I'm moving to an AIOP V2 and this is the first helpful thread I've found on how to enable an external GPS/Compass module. So by cutting J2 and J3, are these the two tiny traces you're talking about?:

The ones connecting the two right pads on both SJ2 and SJ3?

Also, I'm planning on using MegaPirate. Any idea how to change the code to allow compass input from the I2C port? I assume that's what is used...

Thanks very much for this thread.

Arakon · Post by **Arakon** » Mon Sep 15, 2014 5:36 pm

Once you disable the onboard compass, you simply hook up the external compass to i2c.. no other changes needed.

eatkabab · Post by **eatkabab** » Mon Sep 15, 2014 6:49 pm

Wow thanks for the super quick response.

So it's really as easy as finding that line of code in the config.h, flipping it to 'off', and plugging in the compass module? It kinda auto 'installs' itself or the board knows to look for it? I'm assuming MegaPirate is more straightforward than multiwii but I haven't used either yet...hardware on the way.

Arakon · Post by **Arakon** » Mon Sep 15, 2014 7:04 pm

No, you have to cut the traces of the jumpers pictured above. You can't disable it in software, since you'd automatically disable an external compass too.. they use the same address.

eatkabab · Post by **eatkabab** » Mon Sep 15, 2014 7:26 pm

so cut the two tiny traces I pictured in my post, plug into I2C and done?

Arakon · Post by **Arakon** » Mon Sep 15, 2014 7:31 pm

Exactly.

eatkabab · Post by **eatkabab** » Mon Sep 15, 2014 7:40 pm

really?! No software to configure no issues? Just get a compatible gps/compass module (Ublox 6M I presume)?

brewski · Post by **brewski** » Mon Sep 15, 2014 9:01 pm

eatkabab wrote:really?! No software to configure no issues? Just get a compatible gps/compass module (Ublox 6M I presume)?

I used an ext compass board but the combined UBlox + Mag will also work. As far as firmware goes you just need to undefined line in Def.h and define mag sensor type in I2C sensors in Config.h.

Arakon · Post by **Arakon** » Mon Sep 15, 2014 9:06 pm

I didn't have to make any software changes and it worked right away. Both are hooked up to the I2C port, and both use the same address, it doesn't matter if it's on the board directly or hooked up with wires. So unless you have issues, try without changing the software first.

brewski · Post by **brewski** » Tue Sep 16, 2014 12:57 am

Arakon wrote:I didn't have to make any software changes and it worked right away. Both are hooked up to the I2C port, and both use the same address, it doesn't matter if it's on the board directly or hooked up with wires. So unless you have issues, try without changing the software first.

Yeah I didn't try it without modding firmware. As both on same address & FC is defined, MW will be looking for a HMC5883 Mag on I2C bus.
If running Megapirates on Crius AIOPV2 you should read this excellent guide http://xxl-modellbau.de/abbildungen/qua ... rateNG.pdf

khaidang27 · Post by **khaidang27** » Fri Jun 26, 2015 8:55 am

i got it. Thank you so much All.
@Leo: i am so sorry ^^ thank you Sir!

Leo · Post by **Leo** » Fri Jun 26, 2015 1:03 pm

Please don't double post. You question has been answered in your other post.

MultiWii