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$15 external compass for APM 2.5

Posted by Scott Reid on September 11, 2013 at 7:45pm

As a followup to a conversation in this thread: http://www.diydrones.com/profiles/blogs/3dr-gps-mag-back-in-stock

I have successfully used this $15 sparkfun HMC5883L breakout board: https://www.sparkfun.com/products/10530

as an external compass on my APM 2.5.

Used the instructions here: http://copter.ardupilot.com/wiki/common-external-magnetometer-for-improved-performance/

The process is even simpler than those instructions, since the sparkfun board is already wired for 3.3V. Just connect four wires and cut a jumper on he APM to disable the onboard compass.

I wasn't able to source the correct cable from sparkfun, but got one that was 1mm OC instead of the 1.25 OC that the APM uses on the i2c port. A little very minor pin bending and hot glue to hold it in seemed to do the trick.

The HMC583L is the same sensor that's on the APM and on the 3DR external compass/GPS module.

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Comments

Josh Potter September 12, 2013 at 6:48am

I've also used this compass. It was more of a I need other stuff from sparkfun and they ship really fast. Fast shipping is important to a lot of customers.
Stefan Gofferje September 12, 2013 at 6:44am

I use an HMC5983 which is the successor and supposedly more precise and more EMI resistant. $6 from ebay.
http://www.ebay.com/itm/350797015473

Additionally, I found a ten pack mini JST 1.25 4 pin with 15cm cable for $4.39, also on ebay.
http://www.ebay.com/itm/181198791446
The same seller also has 3, 5 and 6 pin cables

HMC5883L go on ebay from $3 free shipping.
Scott Reid September 12, 2013 at 6:10am

Thanks TC and John for pointing out the metal screw potential issue. I'll replace that with a nylon hardware and recal.

For some reason I was under the impression that the 3DR external compass was either unavailalbe or way more $$.. For $18 + $3 for the cable I would in hindsight probably go that route just to be able to get the cable and sensor on one order.

-SR
Admin

Thomas J Coyle III September 12, 2013 at 5:16am

@Scott,

I would replace that steel screw and washer with either nylon or brass ones. I have used both nylon and brass hardware to mount my HMC5883L compasses and have not had a problem with mag calibration.

Just a thought.

Regards,

TCIII ArduRover2 Developer
Magnus von Rosen September 12, 2013 at 2:00am

And since this morning,

http://www.hobbyking.com/hobbyking/store/__26861__Arduino_HMC5883L_...

$8.54 when signed in.

/Magnus
Euan Ramsay September 12, 2013 at 1:57am

Woops, sorry, I meant these:

http://www.goodluckbuy.com/hmc5883l-triple-axis-compass-magnetomete...
Euan Ramsay September 12, 2013 at 1:55am

I got three of these:

http://www.goodluckbuy.com/hmc5883l-3v-5v-triple-axis-compass-magne...

All work fine.

I used one of these to hook it up (with one end snipped off):

http://www.buildyourowndrone.co.uk/DF13-4-Position-Connector-19-cm-...

Both companies are much cheaper to ship than 3DR.
Chris September 12, 2013 at 1:12am

All I still need is that cable with DF13 4 pin connector. Just can't find a place with decent shipping to Austria. 3Drobotics ask me USD38.00 for a USD2.50 item. And that is their cheapest rate.
Rana September 12, 2013 at 12:05am

Randy, 3DR external Mag is great have provision for 3.3V and 5V, its price is 17.99US$
Developer

Randy September 11, 2013 at 11:35pm

The external compass from 3drobotics is only $13.04 more of course...just saying..

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