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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      • Disabling int compass solve mine

  • A big thank you to Randy, Leonard and all the developers as well as all the great people from around the world contributing to the discussion. 3.3.1 is absolutely rock solid, safety and stability have improved steadily in the year since I started out in this. It has been great fun for me as well as my High School Students, we have all learned a great deal thanks to this group.

    Thanks to all,
    Fly on
  • my gimbal now works fine on AC3.3.1 rc1 :) thanks again!

  • Hi Randy, I currently using AC 3.3.1. Last time when i test my hex-copter with mission planner 3.32. Firstly, I sent command to take-off to 5 m, it's ok. But when i send commands to take-off to 10 m, it didn't work. Then I switched the firmware to AC 3.2.1, I tried take-off to 5 m and then take-off to 10 m, it worked. Could you give some suggestions. Thanks so much.

  • Does EKF use both internal and external compass data for processing? I know they don't switch in flight (if copter has both). 

    Today I had EKF warnings for Mag.  The external compass is a good 6" away from the power wires, so I'm puzzled as to why EKF is complaining.

    • Developer


      No the EKF only uses the primary compass which would be the external one if you've got it attached.

      • I was having all sorts of issues w/ my little copter w/ auav-x2 board. Auto missions were very uneasy/wiggly, it toilet bowled, it had all sorts of random AHRS and arming errors.  I made lots of posts about it over the summer, but finally found the cause recently..
        Even though I have an external compass, it was the internal compass. 
        After trying everything else, I decided to disable one compass, and just use the other.   If I disable the external compass, north is no longer north, no matter what orientation I set the compass as....  Basically, the internal compass is no good. 
        If I use only the external compass, all is good.  No more random drifting off in some direction.  No more toilet bowling. 

        I guess the developers would know more than me, but my observation has been the bad internal compass did indeed cause issues when both compasses were enabled. 

        • Developer


          That's a bit strange 'cuz the EKF shouldn't be accessing the internal compass.  Basically the internal compass shouldn't be used for anything except the consistency check.

  • Testing 3.3:

    Was really pleasantly surprised: The satellite Spektrum compatible receiver works! Even the channels are in the right order! Great! Love it!


  • Thank's Randy, we don't have to change rc1, it's the same no?

    Another thing, when I installed the 3.3 with pix my OSD read all in 0, I have to change sr values before some reading, now I noticed another persons with same problem, perhaps it's usefull to have the correct SR values for OSD as standard params not to have that problem? or if you are not using osd you need different params?

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