Copter-3.3 beta testing

Warning #1: an issue has been found with Tower's Pause button which can cause the vehicle to fly to an old position if the vehicle has not sent a position update to Tower in some time.

Warning #2: Copter-3.3.2 fixes a bug found in Copter-3.3.1's desired climb rate initialisation which could lead to a sudden momentary drop when switching from Stabilize or Acro to AltHold, Loiter or PosHold.

Warning #3: Copter-3.3.2 fixes an issue found in Copter-3.3.1 which could lead to hard landings in RTL or AUTO if the WPNAV_SPEED_DN was set too high (i.e. >400 or 4m/s) and/or the WPNAV_ACCEL_Z was set too low (i.e. <100 or 1m/s/s).

Warning #4: a bug was found in Copter-3.3 which could cause a sudden crash if you abort a Take-off initiated from a ground station.  Video description is here.  The bug is fixed in Copter-3.3.1 so we recommend upgrading.

Note #1: AC3.3-rc8 corrected a long standing bug in the HDOP reporting.  HDOP values will appear about 40% lower than previously but this does not actually mean the GPS position is better than before.
Note #2: if upgrading from AC3.2.1 the vehicle's accelerometer calibration needs to be done again.
Note #3: set SERIAL2_PROTOCOL to "3" and reboot the board to enable FrSky telemetry like in previous versions.
Note #4: the wiki will be updated over the next few weeks to explain how to use the new features

Copter-3.3.1 is available through the mission planner.  The full list of changes vs AC3.2.1 can be see in the ReleaseNotes and below are the most recent changes since AC3.3.

Sadly this version (and all future versions) will not run on the APM2.x boards due to CPU speed, flash and RAM restrictions.

Changes from 3.3:

1) Bug fix to prevent potential crash if Follow-Me is used after an aborted takeoff

2) compiler upgraded to 4.9.3 (runs slightly faster than 4.7.2 which was used previously)

Changes from 3.3-rc11:

1) EKF recovers from pre-arm "Compass variance" failure if compasses are consistent

Changes from 3.3-rc10:

1) PreArm "Need 3D Fix" message replaced with detailed reason from EKF

Changes from 3.3-rc9
1) EKF improvements:
    a) simpler optical flow takeoff check
2) Bug Fixes/Minor enhancements:
    a) fix INS3_USE parameter eeprom location
    b) fix SToRM32 serial protocol driver to work with recent versions
    c) increase motor pwm->thrust conversion (aka MOT_THST_EXPO) to 0.65 (was 0.50)
    d) Firmware version sent to GCS in AUTOPILOT_VERSION message
3) Safety:
    a) pre-arm check of compass variance if arming in Loiter, PosHold, Guided
    b) always check GPS before arming in Loiter (previously could be disabled if ARMING_CHECK=0)
    c) sanity check locations received from GCS for follow-me, do-set-home, do-set-ROI
    d) fix optical flow failsafe (was not always triggering LAND when optical flow failed)
    e) failsafe RTL vs LAND decision based on hardcoded 5m from home check (previously used WPNAV_RADIUS parameter)

Thanks for your testing!

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      • Hello Vesselin

        I have a strange behaviour in 3.3.2 APM copter version .

        After armed and the motors begin spin, while increase the throttle the 2 front motors spin more than the 2 of back.(quadcopter x frame) and the have response delay for any  throtle change. If i increase throtle for take of

        the copter turn back until back motors touch the ground.

        I tried several times to erase and install again the version 3.3.2  with all procedures with no result.(i have done esc calibration ,radio calibration...)

        Installed the 3.2.1 version and all is normaly.


        Pixhwak from 3dr

        telemetry 433mhz

        T-motors 3508-20 580KV

        T-motors esc 30 amp opto 400mhz.

        battery: 4s 16000mah

        AUW: 3300gr.

        Thank you in advance


        2016-02-19 10-00-15 3.bin.log

        2016-02-19 09-26-41.log

        • Did you check the settings values if same in the 3.3.2?

          Sometimes when you import the settings from previous release version, they are different or some not imported at all. Have to check all PIDs, flags, etc. manually.

          • Thank your for your response.

            I did reset  the full parameters to default after install the 3.3.2.

  • Midflight-Disarm -> Crash

    Hello together,

    I´d like to share my latest experience with you:

    To test the redundancy capacities of a recently built Coax Octocopter X8, I turned off Motor 1 to check the emergency flight behaviour.

    In Stablilize and AltHold Mode, the reaction were OK. Mainly during faster Yaw-Turns the crafts began to shake but always recovered

    As final check I tested RTL. Even though there were some unintended Yaw-turns while retunrning to home-point, the craft managed to reach it.

    As soon as the descending started, all motors where stopped/disarmed and the craft fell to the grund from app. 20m height.

    Even if there were quite unstable moments during the whole test flight, I´m quite sure, that the craft would´ve recovered on the landing process, if no Disarm-Command would´ve occured.

    I´d really like to get your feedback and would be happy if someone (Randy?) could have a look at the log file.

    There are huge and very fast roll amplitutes before the Crash-error, I can´t imagine that they are even physically possible with this big and heavy craft (maybe some kind of EKF error?).

    Kind regards and thank you in advance!



    AC 3.3.2

    AUAV X2 Flight Controller
    8x 4225 390kv Motor, 17x6 Folding Prop
    AUW: ~ 3800g




    • The controller performed well for such “disabled” bird…


      All the flight is quite good, but clear instability in the Roll after both RTL commands. The power to the controller is lower – 4.91V, should be about 5.2V normally. Probably not big issue for this flight.

      Among all the flight the controller gives good Throttle Out. But again after the both RTLs, the Throttle Out have high peaks, and at the 4 min flight time it reached the maximum – 1000.


      All this leading to the conclusion that the controller performed well until height of 20m, keeping the bird in decent flight.

      After all the permanent Roll oscillations and constantly overloaded ESCs, the final Throttle Out 1000 browned the ESCs and motors stopped.

      It happened at line 63.


  • I did some flights with 3.3.3 in pos hold with nothing strange; yesterday I installed the gimbal and assign ch6 to tilt movement as instructions explain, today afternoon forecast indicates no wind so I went to check the gimbal and more functions from 3.3.3, forecast was incorrect but I tried anywere, GPS had some gliches for first time, I was near trees but not the first time that I fly near trees without problem. I try pos hold and guided mode, Pos hl sometimes well some not, first guided test well, second guided test a gps glich and fly near trees so landed and went boxes to look logs  (I hope was the best choice), I found fligth mode 16 err in logs and exf err and suposse  gps cosecuence, In the afternoon, strong wind, I was intrigated and try far from gps interferences and well fixed gps wires with fastik, at the begining the err mode and exf appears again but, this time no gps gliches, I only change firm and program the ch6 for gimbal, I re -check the pwm values and looks well ;What could  be happened?

    The last flight log attached

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    • It's looks something assigning ch6 to gimbal perhaps, because I check older logs and nothing strange, It's looks that affect pos hold mode but I don't know how to solve, any idea? I checked ch6 in basic tunning and is assigned to NONE

      • I recalibrate the radio, little test and now looks well again, I'm going to continue testing.

        But refering to code, I'm not shure if it not an issue that log doesn't indicate the gps glich, only says EKF 1 or 2 err. This is the log with that problem.

        Dropbox - Link not found
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        • Maybe this will help?

          • Thank's Joe, that exact reaction that the copter have, I jump the updated instructions; I have to say that reaction when lost gps was much better than some years ago when the guy flyed like a cohet when he lost gps.

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