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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      • Hi Thorsten,

        The buzzer hasn't moved from its original place, in the top shell.

    • It would probably help Randy / Devs if you could post a log. Bummer about the broken leg :[ 

      • Thanks Richard.

        I'll only have access to the Iris tomorrow. I'll put them up then if no one has a flash of inspiration in the meantime.

        • Developer

          As Richard says, it's guesswork without a log.  The rapid descent at the end is almost guaranteed to be because the battery was getting very low - if so, we will see in the logs that the output throttle was at 100% as it was falling.  This basically means that the battery failsafe needs to trigger earlier.  It could be as simple as setting the failsafe voltage higher or the battery capacity lower.

          • Here are 4 logs to download with graphs for quick view: 2 failsafe crashes, 1 successful RTL test and 1 successful Land test

            Crash 1:

            3702846044?profile=originalCrash 2:

            3702846061?profile=originalSuccessful RTL tests: 

            3702846079?profile=originalSuccessful Land tests:


            Shared with Dropbox
            • Frederic, is you Iris modified in any way?

              Does your buzzer go off when the battery failsafe kicks in?  It usually does.

              Thorsten had a problem similar to this where he found the problem was actually that the buzzer caused a problem with the IMU, because it was too close.  I would think the standard Iris buzzer location wouldn't cause this problem or they would all do the same thing.  But maybe your buzzer has been moved or something?

              • Hi Rob,

                It's an upgraded Iris that I bought new in June 2014. Aside from installing the Iris+ upgrade kit, I made no mods. The upgraded Iris never exhibited this behaviour before, and I've relied on the battery failsafe many times.

                Yes the buzzer does go off when the failsafe kicks in. I have not moved the buzzer - it is inside the top shell. I've opened the shell yesterday to get the logs off the memory chip and did not notice the buzzer being loose.

                Thanks a lot for your help.

                • T3

                  Hi Frederic,

                  I just had a look at one of your logs and I am pretty sure it is the buzzer. It is the exact same thing I experienced. When you switch a flight mode there is a buzzer tone and the IMU readings diverge (yellow and orange lines):3702926936?profile=original

                  In these cases my copters were either falling or climbing for some meters (which seems not to be the case with your copter). After relocating the buzzer all was fine.

                  Looking forward to your test!

                  Best regards,


                  • Developer

                    I'd just stick with the 3M foam that 3DR sells.  Paul Riseborough recommends the "Hobby King pink foam" but it's only sticky on one side.

                  • Ok - Thanks again Thorsten. I'll keep my eye open for softer foam to support the Pixhawk.

This reply was deleted.


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