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 –


    • Developer

      Hi John,

      When the safety button is solid there is nothing being sent to the esc's. I bet if you pull the esc out of the pixhawk while everything is powered up you will see the same thing. This is what your ESC does and has nothing to do with the pixhawk.

    • what do you mean goes into breaking mode? Whenever you remove power from the ESCS/motors they will get "stiff" for a while until all the caps release their charge. This has been this way for well as long as brushless escs came out with caps on them.

      • Well about 18 or so multi rotor builds over last 6 years and I find they don't all do this my friend. It doesn't happen with my NAZE32, APMs, Openpilot Revo, DJIs and so on. I have only had this happen one time ages ago, but cant remember now why and which FC it was and then how I fixed it.

        If what you say should be true, it should happen in every case then?  So then why doesn't it happen if I unplug the battery when it is "armed"?   Yet when it is put into safe mode the motors go "stiff" after 5 seconds and then stay stiff after I unplug the battery.

        I would assume if the caps are doing this then they would do it constantly armed or disarmed? Why is it that when armed they are not and when disarmed and put back into safe mode, after 5 seconds they go stiff again? I would have assumed once put into safe mode, nothing should be going to the motors or the ESCs caps? Yet they are?

        This is a Pixhawk fw issue I think.

        • It has ALWAYS done this on every one of my multirotors. From back when I started using the early miltiwii boards, all the way up to my hawks. Here is a pretty good explanation why.

          • Then obviously not all ESCs do this then. The other ESCs I use don't do this on my 800 hex, min quads etc, and the ones I now have are the first time I have used them. Anyway thanks for you input, its now crystal clear.

  • Any update on getting terrain following in the next update?  Is this still on track?  Just curious after having to abort a mission yesterday in a remote location.  Flight started in a bit of a bowl and the intent was to fly the perimeter of a farm about 30 feet above the tree line.   But on the first leg with Iris about 300 yards away heading over rising terrain I didn't like the margins and engaged RTL.  Yes, I know I could sit down with a topo map to plan such a mission but how much simpler it would be if if the waypoint altitudes could be AGL and not relative to takeoff point.  Hoping to see this very useful feature...

    • Just fix a LIDAR to it.

      • So far, LIDAR sensors like LidarliteV2 don't work in auto flight mode.  I do a lot of mapping is areas with 50m trees lol, not so cool when your mission  is at 80m and your vertical data isn't spot on.  It would be nice if you could set a limited minimum distance between unit and ground independent of the AGL you set in Mission Planner.  If you could set say 20m as you safety margin.  Take off and fly the auto mission at say 80m AGL, but if something encroaches into that 20m the autopilot would ascend to whatever altitude that put 20m between it and the object.  After clearing the object it would return to the requested AGL (sensor pretty much useless beyond 40m).  Or just got get a Nvidia Jetson...  So want one of those lol!

        • What I was thinking is that if the GPS database includes elevation (maybe a bad assumption?) that when you load waypoints into Pixhawk you could specify AGL relative to each waypoint instead of relative to takeoff elevation.  Seems that would be far more useful and would streamline mission planning in hilly areas.... no need to break out the topo chart or guestimate.

          • Developer


            What you describe is planned for Copter-3.4.  I have a half-baked development version that uses the terrain database (fed from the google-earth or other mapping services) but it needs a bit more development and lots more testing before it's ready.

This reply was deleted.


DIY Robocars via Twitter
RT @SmallpixelCar: Wrote a program to find the light positions at @circuitlaunch. Here is the hypothesis of the light locations updating ba…
6 hours ago
DIY Robocars via Twitter
RT @SmallpixelCar: Broke my @HokuyoUsa Lidar today. Luckily the non-cone localization, based on @a1k0n LightSLAM idea, works. It will help…
DIY Robocars via Twitter
@gclue_akira CC @NVIDIAEmbedded
DIY Robocars via Twitter
RT @luxonis: OAK-D PoE Autonomous Vehicle (Courtesy of zonyl in our Discord:
DIY Robocars via Twitter
RT @f1tenth: It is getting dark and rainy on the F1TENTH racetrack in the @LGSVLSimulator. Testing out the new flood lights for the racetra…
DIY Robocars via Twitter
RT @JoeSpeeds: Live Now! Alex of @IndyAChallenge winning @TU_Muenchen team talking about their racing strategy and open source @OpenRobotic…
Nov 20
DIY Robocars via Twitter
RT @DAVGtech: Live NOW! Alexander Wischnewski of Indy Autonomous Challenge winning TUM team talking racing @diyrobocars @Heavy02011 @Ottawa…
Nov 20
DIY Robocars via Twitter
Incredible training performance with Donkeycar
Nov 9
DIY Robocars via Twitter
RT @JoeSpeeds: Sat Nov 6 Virtual DonkeyCar (and other cars, too) Race. So bring any car? @diyrobocars @IndyAChallenge…
Oct 31
DIY Robocars via Twitter
RT @JoeSpeeds: @chr1sa awesomely scary to see in person as our $1M robot almost clipped the walls as it spun at 140mph. But it was also awe…
Oct 29
DIY Robocars via Twitter
RT @chr1sa: Hey, @a1k0n's amazing "localize by the ceiling lights" @diyrobocars made @hackaday! It's consistently been the fastest in our…
Oct 25
DIY Robocars via Twitter
RT @IMS: It’s only fitting that @BostonDynamics Spot is waving the green flag for today’s @IndyAChallenge! Watch LIVE 👉…
Oct 23
DIY Robocars via Twitter
RT @IndyAChallenge: Congratulations to @TU_Muenchen the winners of the historic @IndyAChallenge and $1M. The first autonomous racecar comp…
Oct 23
DIY Robocars via Twitter
RT @JoeSpeeds: 🏎@TU_Muenchen #ROS 2 @EclipseCyclone #DDS #Zenoh 137mph. Saturday 10am EDT @IndyAChallenge @Twitch
Oct 23
DIY Robocars via Twitter
RT @DAVGtech: Another incident:
Oct 23
DIY Robocars via Twitter
RT @DAVGtech: What a great way to connect why @diyrobocars community is so valuable and important! Have to start somewhere @IndyAChallenge…
Oct 23