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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    •  I am on 3.3rc10 and I think I have the same issue with dataflash log - it seems mission planner either downloaded just a portion of a log or ready just portion of the log.

      I am at work, I will try to upload the log when I get home.

  • If I have a copter with LidarLite on it and fly a Auto mission and set the height to 25 m in mission planner will it use the Lidar to keep the height on 25 m above the ground?

    I use to fly in areas where there is no terrain data so it would be nice if I could use the Lidar to keep the altitude over ground.

    • Developer


      No, I'm afraid the lidar-lite altitude is not used during missions.  We're looking to add Terrain Following during missions using the google maps altitudes to Copter-3.4 and we've discussed also incorporating the range finder altitude into that but I can't make any promises yet.

      It's slightly more complicated than it seems because for a proper solution we need to allow the pilot to specify what altitude they want to be used during the mission (i.e. alt-above-home, alt-above-sealevel, alt-above-terrain) which affects a number of parts of the system including the GCS, the mission command storage and finally the vehicle position controllers.

      • Hi Randy!
        For thoose who fly in an area without google maps altitude (for me Storlien, Sweden) and not so flat landscape it would be a great help to be able to set desired altitude to be used by Lidar, and then just plan the route.

        Is it possible to implement it as a security parameter in auto to not go below ground altitude xx m. reported by lidar?

        Holding my thumbs for that it will be implemented in future releases for this great product.

      • Please spend the time to incorporate Lidar for missions. It would be great for many things from simple terrain following to mapping.

        Not to mention it is just plain cool!

        Randy, do you already have a Lidar lite or does somebody need to send you one?
  • Is 3.3 out?
    Checked in MP for beta FW and I got "APM:Copter V3.3 Quad"?
    Or a bug in MP.


    • I think it´s out since 14 hours.

      APM:Copter Release Notes: ------------------------------------------------------------------ Copter 3.3 29-Sep-2015 / 3.3-rc12 22-Sep-2015 Changes from 3.3-rc11 1) EKF recovers from pre-arm "Compass variance" failure if compasses are consistent ------------------------------------------------------------------
  • Hello my name is arpan I just joined diy drones . I am facing problem with apm I have rc timer apm 2.5.2. Problem is when I am testing motors on motor test page (I have a hexa copter )so when I hit motor a m5 starts rotating.when I have checked the ecs coneutrons. To the apm more than 10 times. I have uploaded v3.2.1 . When I hit me some other motor starts rotating. Pls help
    • Hi Arpan 

      Welcome to DIY drones !   I see you posted a message relating to Version 3.2.1 ..Please can you post this message on the correct place for 3.2.1 support at

       This place is for 3.3 version running with Pixhawk 32 bit controller. 


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