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!

You need to be a member of diydrones to add comments!

Join diydrones

Email me when people reply –


  • I am using RC 10 still and had a odd bug after an Auto mission. The mission went ok, but after landing and automatically disarming I could not rearm in Althld. After the first mission while changing modes and trying to rearm the quad finally desided to rearm after 2 mins of setting.

    After the second mission I could not get a rearm at all even after several minutes.
    MP only showed a "Disarmed" message on screen.

    I will have to wait until this evening to review the logs.

    I was wondering it this had happened to others as well.
  • I'm trying to track down some compass issues on a AUAV-X2. If I disconnect the external compass on rc12, COMPASS_EXTERNAL still always says "1" after I reboot. I tried setting manually and it always gets reset. This is supposed to be autodetected on a pixhawk - anyone else see this behaviour? The compass IDs also do no get reset - are these determined at calibration time or on boot? I had assumed boot, but maybe its only calibration?


    • Different question. If I calibrate the internal compass on its own I get offsets of (52, -104, 327), if I calibrate them together I get (-15, -32, 127). How can this be? I would expect the values to be close-ish, but they are miles apart!

      Both times I had a good set of data points and the output is relatively stable if I rerun the calibration.

      Or is this more a mission planner question?

      • Developer


        I agree with you that there shouldn't be any difference to the compass calibration results depending upon how the compasses are calibrated (how many, in what order, etc).

        .. and as you guessed, it's more of a mission planner question I think.  The compass calibration logic is completely within the mission planner.  For Copter-3.4 the calibration will be moved to the vehicle (it's already in master).


      that is apparently a support for multiple redundant compasses that would be awesome if it worked - but as all external compasses units in the gps receivers sit on same hardware address nothing of that works.

    • I am still on rc10 but if I disconnect gps with external compass it for sure sets compass external parameter to 0.

      • Never mind - I had pulled the GPS cable so the compass was connected but not powered (I'm guessing).

        Disconnecting the compass does result in the external parameter being set to 0.

  • Popping in here to say that 3.3 rc12 ran great on my IRIS+. Granted I was not able to test every single mode and function but out of the modes I was able to fly in ,AltHold, Sport, PosHold, Circle everything went smooth.  First flight no gimbal. took off fine. Got to a good altitude and let AutoTune run. AutoTune complete. Ran tests in AltHold, PosHold, Sport, Circle, Land, all good no issues IRIS+ was 100% spot on. Second flight gimbal attached. Launched fine. tested same flight modes, all good. No issues, IRIS is solid. Had 12sat 1.4hdop on both flights. Had my ground station up and running but I was flying IRIS+ a few feet away so I wasn't see what the HUD was displaying. 

    I would post my logs but the issue of "Error receiving log list" that other's have run into is prevalent. I have tried some of suggestions that were previously posted but I am still receiving the error....I will continue to try and figure this anomaly out.

    Todd H

    Oh and thank you to all the testers and programmers. I don't think that can ever be said enough.

This reply was deleted.


Gremsy liked Gremsy's profile
Mar 12
DIY Robocars via Twitter
RT @chr1sa: Donkeycar 4.4 released with tons of new features, including path learning (useful with GPS outdoors), better Web and Lidar supp…
Nov 27, 2022
DIY Robocars via Twitter
RT @NXP: We are already biting our nails in anticipation of the #NXPCupEMEA challenge! 😉 Did you know there are great cash prizes to be won…
Nov 24, 2022
DIY Robocars via Twitter
RT @gclue_akira: レースまであと3日。今回のコースは激ムズかも。あと一歩 #jetracer
Nov 24, 2022
DIY Robocars via Twitter
UC Berkeley's DIY robocar program
Nov 24, 2022
DIY Robocars via Twitter
RT @chr1sa: The next @DIYRobocars autonomous car race at @circuitlaunch will be on Sat, Dec 10. Thrills, spills and a Brazilian BBQ. Fun…
Nov 24, 2022
DIY Robocars via Twitter
RT @arthiak_tc: Donkey car platform ... Still training uses behavioral cloning #TCXpo #diyrobocar @OttawaAVGroup
Nov 20, 2022
DIY Robocars via Twitter
RT @emurmur77: Points for style. @donkeycar racing in @diyrobocars at @UCSDJacobs thanks @chr1sa for taking the video.…
Nov 20, 2022
DIY Robocars via Twitter
RT @SmallpixelCar: Going to @diyrobocars race at @UCSDJacobs
Nov 8, 2022
DIY Robocars via Twitter
RT @SmallpixelCar: Race @diyrobocars at @UCSDJacobs thanks @chr1sa for taking the video.
Nov 8, 2022
DIY Robocars via Twitter
RT @PiWarsRobotics: Presenting: the Hacky Racers Robotic Racing Series in collaboration with #PiWars. Find out more and register your inter…
Oct 23, 2022
DIY Robocars via Twitter
RT @Hacky_Racers: There will be three classes at this event: A4, A2, and Hacky Racer! A4 and A2 are based around UK paper sizing and existi…
Oct 23, 2022
DIY Robocars via Twitter
Oct 23, 2022
DIY Robocars via Twitter
Oct 19, 2022
DIY Robocars via Twitter
Oct 18, 2022
DIY Robocars via Twitter
RT @NeaveEng: Calling all UK based folks interested in @diyrobocars, @f1tenth, @donkey_car, and similar robot racing competitions! @hacky_r…
Oct 13, 2022