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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Vincent what are your current parameters? I am very curious becase I think the standard ones have to be tweaked a little to get a good reliable flight.




I think you missed something...


There's surely nothing in the code or to do with APM that could make an ESC smoke?

Sounds like dud ESC's (chinese imports, hobbywing, turnigy?) coincidentally installed on the third arm.

The only reason smoke is going to come out is that you somehow overloaded the BEC. If you aren't using a power distro board that isolates the 5volt power coming from the ESC BEC (regulator) then it's highly likely when the other motors begin to draw some serious amperage and those motors aren't working (the beeps due to wrong input signal or other issue) suddenly you have a high current ground loop or 5 volt loop and something has to give. It's known there were different wiring diagrams and connections for octo.

Again, this is a wiring problem, either not isolating the BEC (the middle pin of every ESC but 1) and or a massive ground loop when the current comes unbalanced.

Yes you have a code/wring problem too with those two motors but the wiring is what caused the smoke, not the code.

You can send invalid signal to an ESC all day long and as long as that signal isn't above 5 volts, it's basically impossible to cause smoke to come out.


I've warned in another thread that just this type of thing could occur when using different ESCs and then just plugging them into the APM board thus tying all the BECs together and the BECs being different designs and part numbers fight each other to maintain the 5 volt power to the APM. Clearly this is the most likely cause of your issue. Being that on APM1 the signal pins on an octo were not in a bus row like APM2, your wiring isolated those BECs and you just didn't even catch it.

Thanks for the replies. I've build a few big octos and know the system inside out, it's def not a wiring issue as I only have signal wires from ESC going to APM, and +- into a power disto circuit, as with all my other copters. The reason I thought it might have been code is a possible new code change which left out octos (this happened before when they brought out a new version, they did motor section re-code and no1 remembered to check the octo/hex settings, I was first to try fly with octo, which did not work ;) )

I've replaced the ESC and all working now, altough still getting a delayd start up tone from the same new ESC, 7 motors beep together, but 3rd channel is late.... ??

Coinsadance that two octos do the same on same channel ? perhaps.

???? oooops

Well i fly with default parameters and flies good with a 1,6kg frame. But adding the gopro + video tx is rather unstable.

did you try also replacing that same motor? I had nearly exactly the same problem and could smell burnt electrics, although it still flew. What I found is one of the windings had a loose wire that was rubbing against the inner housing. it was only slightly intermittent and made the motor/esc behave very strangely. Eventually it shorted out one of the chips on the ESC.   Id check the motor and at least test it with a different one

The only way to trouble shoot this is to put some o-scope captures of the output signal at startup. Again, based on what I know, 90% of these cheap ESCs use an Arduino chip as the controller and basically, you're taking the ouput the the 2560 pin on the APM and sending to to another Atmel 5v 8 bit microcontrollers input pin. Even if the pin was left high or low, I don't see how that results in smoke. Maybe there is flaw in the ESC code that a perfect combination on the input pin crashed it's microcontroller such that all three Mosfets turned on thus shorting phase to phase. A more detailed look at what failed on the ESC would be far more fruitful in determining exactly what failed and the root cause rather than postulating that some errant signal from the APM caused the esc to fail.


I'm not in anyway doubting your claim there might be a problem in the code as a delayed signal on channel 3 is a problem, I just consider that a different issue than burning up an ESC. This weekend, I'll try and set up my APM 2 in octo and take a look myself and see if this is reproduceable (the errant pwm) and while I'm not up to speed on the latest code, definitely can try to help determine from a signal standpoint what's going on. Worst case, I send an ESC up in smoke as well. If it does go up, might be a good time to get a look at the ESC source code (probably cannot get it), look for error conditions that could cause it to go up. Again, I'm not doubting you in any way, just more concerned there is a magic trick here that is lurking in our ESCs if given the wrong signal. Almost every ESC I have touched has the same basic architecture and the same micro. The 20A and 30A appear to be running the same firmware, so again, i have a new concern an errant signal can let out the magic smoke.

If you can, some pictures of the ESC that did smoke might be helpful. The fact that this happened twice is of concern. Again, there are two issues, one is possibly bad code making errant signals out of channel 3, and far worse, is an esc that burns when it receives this signal.

Finally upgraded my AMP2 from AC 2.1.X to 2.5.3,

What a nice improvement! I now feel that the Acro and Stabilized modes on my quad are as smooth and controllable as they are with a MultiWii board.

Need to find a bigger space to test Loiter and Position modes (what is the difference again?).

Hi, Vincent
have the same frame.
 0,145 pitch rate,
 throttle trim 348
thr max 900.
the other parameters for defects. fairly stable with little wind to keep very small jump height due to uneven weed
engines and propellers XAircraft 10x4.5. apm 1, code2.5.3, 10 amp Turnigy esc, 2650 45c, LV EZ4, contour hd camera, and other a transmitter connected to  5.8GHz 200mw.
weight 1,350kg autonomy 10 minutes....

I flew my new crash quad last night ( I call it the crash quad because I built it purely for testing the extremesI can try out on AC/APM ) but I flew with my open pilot cc board and its so easy!!!.. what a great system! I hate to rag APM and I like this as well and am awed by the magnificent development and great work done on it, but OP really leaves it for dead for ease of use. I had it fitted, calibrated and flying all  in under 15min. and didn't even look at the PIDS.  Even their GCS is so intuitive and the board is small and a brilliant piece of hardware. . Only draw back is it doesn't have GPS autopilot yet and its so slow to develop. I often dream of the day that OP and AC join hands and then really make some great advancements in UAV. 

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