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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  • Randy, Leonard,

    After finally be able to download RC9, due to very bad internet connections at my current holiday location, yesterday I had the first flight with this firmware.

    In the meantime read the Blog post of Leonard, about the Motor Bel Play, and the feedback from Wes which basically delivered the proof that this should bring down the Z Axis Vibrations, I removed the play on all 6 Motors (power usage is going up a little (2 amps)), as I did have quite some up and down movement on the 4114 I am using.

    After taking it up, the motors already sounded much more monotone without the occasionally quick ramping up like they did in RC8, so it did fly much better as before...

    In the logs however I do find clipping, but it's not going up as high as before...

    Vibrations seems to be lower as well, in comparison with the previous logs I looked at

    Looks like the latest changes in RC9 are working out.

    Thanks Devs !

    Logfile :

    P.S By looking at the previous log of RC8, it seemed I did have an unhealthy barometer value as well, as somewhere just 

    before the uncontrolled altitude gain, the Baro switched 2 meters within 100ms, which is hardly something you can trigger by flying I guess....

    I would have expected a small tweak to the EKF parameter to make the Barometer less important, but don't see the change there...? , so I guess it's done somewhere in the EKF code ?

  • Randy,

    On this "Error Compass Variance" issue I and a few others seem to be having with Pixhawk Lites, what specifically are the 2 things that are being compared and found to have a variance, and what is the threshold? Might help if we can graph the 2 variables and see if they can be improved.

    Also, one thing I have noticed with this controller. When I go into a compass calibration using live calibration and the compass dance, the calibration completes most of the time before I have completed the full dance, if that makes sense.

    Thanks for your help!


    • Developer

      Scott, Craig,

      Doing these kinds of tests you mention would be great.  Make sure to provide dataflash logs of course ideally with the logged-while-disarmed LOG_BITMASK set.  So far Luis and Scott have provided logs and they've shown real physical issues instead of firmware problems but in any case, more data would be greatly appreciated.

      I think using the latest beta mission planner is easiest.  It's got a new live EKF viewer that shows the compass variance as a bar that changes from green (good) to orange to red.


      • I have a dumb question. 

        I finished the 3.1.5 and 3.2.1 on the 1st hawk lite today but now I am going to do the 3.3-rc10 but I need a howto on the auto tune for 3.3.

        On 3.1.5 AT took just a few minutes so I was able to complete on a single battery [2200mAh 4S]
        on 3.2.1 AT took a LOT longer and it was a little windier so I wasn't able to do it all on the first attempt but was able to complete on a 2nd attempt [less re-adjusting]. Now it seems that since 3.3 adds yaw that there is no way I will be able to run all 3 axis on a single battery and I see you can set to test whichever axis you want once or two at a time what is the exact processing doing so.

        When I do the AT on 3.2.1 and older, it does the tests and then stops then I turn off AT then switch to Stab, then land and disarm. What am I to look for if I only do 1 axis at a time? Will it do the dance, then stop, then I do what? Turn off AT and then switch to Stab and then land? How will I know it's done with each "leg" of the test?

      • Just tried the EKF / Vibe viewer of MP with DJI F450 Frame DJI E310 Propulsion kit, CUAV Pixhack mounted pretty hard onto 2 HK Sekisui 3mm pads with AC 3.3-rc9 , nice feature, I´d like to have portable. Sorry for the video quality, just a quick´n dirty backyard video, single hand operation.Primarily PosHold.

        Btw.Stock settings(Default PID )no compassmot done (might explain the orange/red compass bar @ throttle peaks?).Surprisingly the PIXHACK doesn´t suffer of bad vibes..about the same I had with PIXHAWK mounted a lot softer onto 3DR foam.

        pixhack f450.jpg

        pixhack sekisui.jpg

        • Developer

          That's the first real-time vibe viewer test I think.  Cool to see!  ..and apparently no problems with vibes on this copter!

          • Thx,Randy. Your announcement of this nice tool just came right in time for me, since I´ve been recently worried about higher hardware requirements of the 3.3-rc concerning vibes and additionally potential insufficient internal damping of the CUAV FC. It always hard for me to find out, what´s really wrong. So this seems to be a "fool proof" fast helper for confidence.

            • Developer

              Yeah, I think this and the EKF viewer are really going to help people diagnose issues with their copters before they lead to a crash or flyaway.

              The next step RobL and I have been discussing is a real-time "control" display.  So this would give an objective warning and measurement of how good/bad the vehicle's attitude control is.  So when the vehicle is dutifully maintaining it's desired roll, pitch, yaw (and perhaps position) this display would be all green but if it starts to lose control in one (or more) axis the display would go orange and then red.  This fits in well wit how we diagnose bad copter behaviour - normally the first question we try to answer is, "was it an attitude estimation problem or was it a control/tuning problem?".

              Anyway, this idea won't make it into AC3.3 but maybe AC3.4.

              • I don't suppose those nice features will be in APM Planner for Mac's will they? Is a lot of what's needed for that with the GCS software itself too right? aka Bill would need to work with you guys on that for APM Planner? Sounds like a great visual way to get an idea what's going on! 

                • Developer


                  They should go in for AP2 as well.   I've certainly raised issues for the EKF and vibe monitors to Bill Bonney and I know he was looking at them.

This reply was deleted.


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