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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      • just flew in a bit of wind.. on 3.2.1 i had no issues stock params pids ..on a zmr 250 frame... i just used 42hz instead of the default.. drifts slightly to the left.. maybe because of the wind.. but omg my heart was racing.. used a 20 c 1300mah zippy batt 10 bucks on hobby-king got about 4 min before it gave me my warning..

        3.3 is just too buggy now..... im using the micro pixhawk from hobby-king

        with the apm micro sensors.... no issues once i switched back with the  compass issue..... even after i choose which one.. from what i understand the pix picks the external one if its attached automatically but i had to manually go into mp and choose 1 which is external.. then i 3.3 rc12 all the issues arose on a clear day too.. everything calibrated...  now my external gps takes a long time to lock on..

        when i use my 450 quad with apm 2.6 its almost instantaneous ..

        maybe because its a official one and hobby king uses Chinese clones i dont know.. but once i switched back flew great.. alot of up and down and a little drift to the left.. but with 10 mph winds maybe thats normal.. held  loiter fine..

        with all my money invested around 500 dollars on this little 250 quad i was sooo nervous lol.. 

        the cool thing i didnt have to touch the pids then again i was only hovering and in a small back yard... but pretty stable 

        heres some pics of my setup..

        1806 motors.. Chinese qav250 frame. 

        12 amp afro esc's

        micro pixhawk with gps and pd board

        3 blade 5x3 props

        spectrum 6210 receiver with satellite 

        dx8 radio

        3dprinted parts for cell phone holder

        telemetry kit

        galaxy s4 phone as tablet

        ppm encoder




    • Reload the params and double check the internal is still set to be off. If it is then that warning seems to be a mistake doesn't it? 

      • yup im getting a green lite on the pix now..

        im getting bad velocity  but before i was a yellow.. so now im sure it will fly... 3.3 has bugs that need to be fixed and looked at

  • auto analysis doesnt work anymore? is something wrong on my end? I get pop ups saying 'time' and then 'bad input file' but the logs open fine when i review them. Also im using the latest beta mission planner

  • Parachute function test was success with firmware 3.3. Test sessions covered two manual ejects and two automatic recoveries. One motor were killed mid air by cutting power off using relay. In this blog you'll find more info.

    • how much weight those it all add up?

    • very cool!!!!

  • I flew 3.3 c12 tonight and flew in alt hold and pos hold and both were improved from 3.2 I think. Alt hold was more consistent even in yaw'ing and or tight circles. Previously my quad would gain in one direction or lose in another before but now it's just... well ... awesome.  I then flew around in pos hold up to and round 15 mps and noticed a more consistent posisition hold and braking to stop position. Not a huge gain over 3.2 but seemed more consistent. Smoother would be the best way to describe it.

    The biggest improvement for me was seen when I chopped the throttle from about 45 meters and it dropped like a rock BUT was completely stable without the wobble from the prop wash that was VERY apparent with 3.2. NICE!!! WOW!!!

    Just a side note I didn't do any auto tune after updating to 3.3. So it was very apparent to me even without that it was much improved.

    I didn't do any auto.... But the two main things I want't  to see improve did!! Altitude. [ over water this is critical ] and pos hold.

    But perhaps the best thing to mention or note for me is NO errors mentioned. No EKF or Compasses inconsistent or anything. It just fire out of the box sweet.


    • Hi Richard,

      What are the specs of the craft you were flying? Thanks -


      • Give or take it's a 550 quad I built myself with 1100KV T motors and a 3s 5200 batt. I use and all in one ESC. A Taranis set up . 3702721808?profile=original

This reply was deleted.


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