ArduCopter 2.5 released!

Version 2.5 of the ArduCopter code is now available in the AP Mission Planner and in the downloads area!



  1. The first ArduCopter code release optimized for the APM 2.  Leans and drift should be much reduced or even eliminated for most users.  This was accomplished through a number of core improvements to the DCM implementation by Tridge like this one and this one.
  2. Loiter and waypoint following should be improved due to a D term bug fix, some tuning and the improved DCM performance mentioned above.
  3. On start-up, the yaw heading is updated with first successful mag read (so you should no longer see the slow rotation from north to your actual heading).
  4. Increased output rate to ESCs to 490hz.  This update rate is also user selectable using the new RC_SPEED parameter.
  5. hexa copter stability patch bug fix (should resolve slight flattening when pitching forward and accelerating very rapidly).
  6. improved baro filtering
  7. fix to dataflash logging of Mag heading
  8. addition of H1 swash plate type and bug fix for proactive yaw compensation for collective pitch changes for TradHelis.



The default PIDs are optimized for a 3DR/Jdrones quad with 850 motors and 10" props. If you're using more powerful motors/props, start by turning down Rate Roll P in 25% steps.

While some testers have reported very good flights with the default PIDs, some have reported that this release is a little "sharper" due to the DCM improvements and have found they needed to:

     reduce stabilize P by 10% (i.e. 4.5 -> 4.2)

     reduce stabilize D by 30% (i.e. 0.15 -> 0.10)

     increase rate D from 0 to 0.001

Tuning loiter can be tricky.  Refer to the discussions which will appear below for more community feedback on what parameters work best.


Please post your feedback in this discussion.  For enhancement requests  and bug report, please add them to the arducopter issues list.  When possible please include logs (tlog and/or dataflash) and tell us whether you're using APM1 or APM2 and what version of the software you're using (presumably 2.5 but tell us anyway!).


Thanks for this release go to the developers (both in the core team but also those who have provided bug fixes through the issues list) and also the community members who participated in the previous release thread and provided some great detailed information in the form of issue reports and logs which allowed us to nail some bugs!


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  • Yes and yes. I used exactly the same method for correcting mine. At least I'm not the only one. Maybe we need to find the root cause for this and get it included in the manual. I expect this will be due to a local magnetic field caused by the hardware.

  • I thought it would be interesting to mention an observation I made regarding magnetic declination.

    In my experience, setting the correct magnetic declination for your location is not enough. You also have to perform procedure to establish a correction factor for your particular airframe. Before I go any further with this, am I the only one who has had a similar experience? 

  • Developer

    We're getting close to pushing out the 2.6 release so I have dropped a Beta version in the downloads area.  This version has not been extensively tested yet so please use with caution!


    This is a smaller release than 2.5 was but still includes these improvement:

       1. Improved compass offset calculations by Tridge.

       2. Automatic compass declination on first GPS lock by Adam Rivera.  This will be on by default but you can turn it on/off by setting the COMPASS_AUTODEC parameter to 1 (=on) or 0 (=off).  When enabled it will overwrite your declination when you first get GPS lock.

       3. AP_Motors architectural improvement by Randy including addition of "stability patch" for Octo and Octo-Quad.

       4. LED improvement by Robert Lefebvre.  APM1 only for now.  More details will be provided by Robert at the official release time.

       5. improved logging of loiter and roll, pitch and yaw rate controllers by Randy.  Logging of these controller's P, I and D components can be enabled by going to the terminal screen, type "logs" and "enable PID".  Next time you tune with CH6 you will see new PID-XYZ lines appearing in the logs.


    The AP_Motors change (#3) is the most risky and that is what we would like people to test.  Ideally we'd like at least one person with each of these frame types ( Quad , TradHeli , Tri , Hexa , Y6 , Octa , Octa-Plus) that:

         a) the motors test from the CLI menu works ok and that the motors spin-up in the correct order.

         b) stabilize mode is ok (no need to test higher functions like loiter, RTL, Alt hold as none of the flight controllers have been modified for this release) 

         c) ESC calibration works (please be careful! take your props off when trying this!) -- this is more optional.


    It's also possible #2 has fixed the camera twitching that people have reported so if someone could try that out, that would be great.


    Thanks for your help!

  • can somebody explain how to program or activate flight mode in mikrocopter calledfree care in multiwii head free, not as it teeth in arducopter, but if I would like to know how does the programming sa to keep the orientation in this mode. thank you very much

  • My APM2 came in this week.  :-)

    Today I had some time to test.

    I used an DIY frame 50 cm with KDA 20-22L and APC 10x4,7props powered by a 5000mAh 30C batt

    It flew very nicely with default pid's

    One thing I'm battling with is the fact as soon as I swith to Alt Hold, lets say from about 1,5m, the quad goes up to 3 meters. Retried from 1m and again it goes up to 3 m. Above the 3 meter it stays at the desired height.

    Its like the 3 m is the minimum.

    I have no sonar attached.

    Could this be a parameter??


    Attached is the log

    2012-04-13 20-56 8.log

  • My second APM1 board is missing a diode that some how got knocked off. Is it possible to just power the APM1 via USB together with the power hack?

  • Marco.... know if you can work with ultra pwm speed as they work from 200 to 1200.and be able to change the code to use? ... I'm asking because I have a plate alsomultiwii and that some codes were changed and you can use that speed, thanks

  • I see many problems with 2.5.3. which can be really safe to fly? .... you can still rely on2.0.49? I appreciate your help.

  • I tried today the new version 2.5.3. After the two and a half minutes quadro flip and crash. Can someone wiser please tell me what was wrong by looking at the log file?

    APM2, Quad X, ROXXY 2827-34 760kv, APC 12x4,7, 4s 6000mAh, flight weight 1700g, default PID:s

    2012-04-12 19-36 7.log

  • you are absolutly correct!

    Was testing indoors the entire time.


    Went out, got the GPS lock...and BAMM!....its working!



    Should've of tried that first.  I could of sworn, that I used to be able to test indoors before and still have the mode switch.

    Maybe it was changed in the new versions of APM.


    Now its time to test v2.5.3

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