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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  • Hey again guys.

    quick one here, I've tried to read through most of this thread regarding the YAW issue people are having, on my big octos it's almost impossible to fly as yaw is all over the show with 2.5.3, but when going back to 2.3 or .49 its solid.. So obviously not a hardware thing, any help, has this been solved yet ?

    Any help or advice would be great.



  • I want to check the barometer feed. In the tuning "Graph This" box which one do I tick to see the live feed?

  • Hi,


    I had try ttuning Loiter in 2.6 beta, still no luck, the quad will stay for about 5 seconds after that it will fly away for upto 25 meter before I stop the movement by taking the control back. My quad using X525 frame with NTM motor 2836/750 KV. Stability mode fly perfectlly stable and no issue with compass.

    I wish someone can help me analyze my log and give me some hint on which parameter I should tune. I have enable PID logging, and in these flight I use Chanel 6 tuning to tune LOITER_P values, min = 0 to max 1500.


    I had 2 flights and both of them no success in Loiter.




    2012-04-15 13-39 2.log

    2012-04-15 13-40 3.log

    X525(initial loiter)-2.param
  • Barometer Issues!?. 

    Ok, here is another problem Ive spotted in the mind field of hardware issues and for people who continually bang their heads trying to fix them through PID tuning. .

    If you have a housing that is covering over all of your electronics such as a plastic container,.. then when you descend or ascend quickly the pressure inside the container changes and gives your barometer an false reading.  

    For example if you descend quickly the pressure increases inside the container making the barometer think that you are descending faster than you actually are. So the APM will try to compensate this out and try to increase the throttle and this probably cause a bouncing behavior some people are finding happens .

    Some may argue that the barometer cant be this sensitive, but I beg to differ because the pressure variation it can sense for the pressure variances in altitude that it works off is very fine. The pressure change inside the container even for horizontal flight will be enough to for it to sense the changes of pressure in the container.

    This also includes pressure zones around the incoming and out going air stream around the props if they are to close to the container or even if you have an open center frame the pressure zone around the props can possibly still affect the barometer

    Im considering some fixes for this such as a tube that has a H tube branch at its end and that sits above or below the center board.

    I would be interested to know what others view and ideas are on this. .

    Ive opened a separate discussion on this here

  • 3692398562?profile=original

    Just my 2 cents.

    Coming from a Naza on this frame to a APM2, I am very please with the change.  A couple hours of reading and tuning and it is enjoyable to fly in stable mode with my Gopro cam.  To me this is a big jump from my experience with a APM1 2860 from last year.  This frame is 600mm with Avroto motors (750KV) and 11" CF props.  Because of the motors my Rate P is down to .095 and because of the Simonk flashed ESC's my Stab P is up to 8.0.  I spent more time troubleshooting the wrong Gimbal pinouts in the wiki then anything else.  Cut my Thr P in half for alt hold and it shows a very good improvement over the APM1.  I also found that a cover over the center plate also helped with stability.  It cut the wind from vibrating the APM2 which is stretched over rubber bands.  A big improvement with this board was seen when I mounted it an inch and half off the center plate, my mag started working well after that.  Before it was flush to the plate and my Dist board caused horrible problems in air.


    Anyway... thanks for the improvements and the hard work.

  • Hi folks,

    today I uploaded 2.6b code to my APM1.4. Since I do always slight mods of code beause there is still not implemented CH7/4 out reversioning (if someone interested more can be reade here) since I fly traditional tricopter I found small changes in code - new classes introduced (AP_motors and subclasses) This seems to be very nice improvement and this is only part of others. Congratulations to all developers.

    I found also some new feature - COPTER_LEDS. Personaly I use different code for LEDs based on U4eake's inventions. I would put question here on this forum if somebode can explain me how does this work owerall - there is no note on WIKI on it yet.

    Anyway I have to agree with U4eake - architecture of code sure improved but the flying performance doesn't suffice me more than 2.0.49. I must object to auto mode - it really doesn't work for me. Lat and Lon of WPs are  achieved somehow but altitude definitely not. Had mission with 3 WPs, one with 30m alt, second with 150m alt and last back to 30m above home.

    Perhaps there is some problem when copter have no sonar and relays only on baro. Who knows...

  • Hallo peeps,

    Took 2.6beta out for a spin, 3dr frame, jdrones 850 kit, 10*4.5 3S 2650

    Decided to go for the 'out of the box' route so uploaded, set up radio, modes etc etc. Manually entered my mag dec, no calibration assuming it would be done for me at first GPS lock.

    And did the following video and log, just press play on the video a few seconds after the log starts for reference mutterings...

    All looks good to me, other than a slight yaw wandering, as seen on the video. Also the logs are showing some crazy compass readings to my only semi trained eye. Should I be twisting cables maybe? The logs look pretty good to me though other wise, I'd love some opinions :)

    2012-04-14 07-14-10.tlog

  • 100KM

    I've never had a good flying copter anymore since 2.0.49.  So yesterday I was tired of it, kicked out 2.5.3 and went back to 2.0.49 on my hexa.  today I flew it in a fair bit of gutsy wind (3-4 beaufort). 

    APM1.4 1280 board with sonar, mediatek gps and magnetometer.  The standard suggested combo in februari 2011.  Hexa with supersimple 20A esc's, KD20-22L motors and 11x4.7 APC props.  Selfmade alu-composite frame.

    Stabilise was very good : no more yaw problem, 20° yawing on takeoff or unexpected yaws during flight, had to lower stabP and rateP a bit and then got a predictable, stable and responsive hexa.
    Althold on sonar was perfect.  It would even follow the shape of my transmitter case when I flew over it.  On baro it varied by about 1m, which is a good as the apm1 baro gets.  Standard althold pid's.
    Loiter was pretty good : it drifted away in the wind for 10m orso, then fought it's way back to the loiter point and stayed there : no circles. (standard loiter pid)
    RTL was very good, except that it climbed a little due to the wind, then got out of sonar range and into apm1 baro range which made it climb a bit further.  I made it RTL cross on the wind and it was nice to see the copter arc into the wind to it's home location (69% in the Tlog).
    Simple mode was perfect and made flying rotating circles easy, as wel as leaning into the wind while rotating.
    Didn't get to test auto cause I forgot to cache google maps on the old mission planner 1.0.88.
    For me this is still the version to beat performance wise.  It may have some bugs, but at least my hexa is a pleasure to fly with it. 
    No cables had to be twisted or copters rewired to get this result...


    2012-04-14 07-29-40.tlog
  • Another question for the group, can I upolad sketches using xbee connection instead of usb?  My usb is a litlle tricky, connects and disconnects at it own will, pins went bad bent in usb? I tried to upload via xbe and I get "warning not a 2156? (i think)  and it freezes, can anyone point me to a how to if you can load sketches via xbee using arduino?

  • I am running ArduCopter 2.5.3 on an x8 using turnigy 18A escs, and Kda 20-22Ls.  I uploaded sketch for X8 via arduino,  but for some reason motors 7 and8 continue to beep, I programmed the escs individually as per wiki, but it still won't acknowledge 7 and 8 at all now.  I had it working sorta, where all esc would beep (odd sequence, sounded like 1-4 beep then 5-8 would beep.  But 7 an 8 would keep beeping till the APM finished booting up.  Now I can't get them to start at all.  swapeed escs and connections, this is definately an issue in the APM2 or software... Anyone having this issue with X8 config?

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