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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                  • Developer

                    Hi Pomaroli,

                    Yeh, that has the new Autotune in it. Give it a go and let me know how it goes.

                    The heavier wiring might change things a little but not much.


                  • hi Leonard, i'm just finished today updating the power system to AWG10 cables and XT90 plugs. just wondering if this will make a difference.
                    I've seen in the firmware repository that there is a newer version of RC1 with date 2014-04-15 is it the newest autotune version ?  shall i give it a try or wait for RC2   ?

    • Thank's Randy, no Pixhawk for the moment but in wish list for this year :) :I think I find an issue in land mode but I have to do another check and post in the correct post (3.2.1) during next week with logs.

  • Sad to see APM dropped.

    • Hi !

      Would it be possible to compile for APM when disabling some of the options ?

      (In the .h file only flash savings are mentioned, no idea of CPU and RAM savings).

      Any hope for that ?



      • Developer


        No chance I think.  There's a massive increase in the number of calculations being done with the EKF and the older, simpler inertial nav (complementary filter) has been removed.  If you're really keen to keep going on the APM2.x boards then sticking with AC3.2.1 and if you're looking to add new features, then working off that branch is best.

        • Hi !

          Thank you for the quick answer. I am fine with 3.2.1. I guess i will wat for a killer feature and then upgrade to Pixhawk. APM 2.5 & 2.6 clones are now sold for < $40, WOW :-)


          • These kind of systems will even get cheaper. One day everybody will be able to afford some brand or another.

            I remember the systems like Micropilot, Hellicomand Profi/GPS and as such years ago when these systems were just coming onto the market. Each system was costing a fortune. Lol...

    • All good things come to an end ...Pixhawk 1 or 2 shopping time.

      • Sure. It would be nice to know the Pixhawk's shelf life before making a purchase.

        My APM 2.5's usable life was less than 2 years and that is with adding an external compass and some other improvements to keep it current. 

        Yes, it is still running and usable but now will no longer be a current FC sadly. 

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