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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      • How did I know you'd be agreeable to this idea?  :)

    • Great idea! I have often held the copter from below [ on first set up ] and in stab mode throttle up until it just about holds it's own weight. You can tell right away if one or more motors are not spinning right or being controlled correctly by moving the copter around a bit by hand... it should of course fight anything making it out of level. I also point each motor down and compare all of them for vibrations. Seems like it's not unusual to feel one motor and or prop still needs some work. You idea is probably a bit safer than what I have done!

      • Use a flight stand-  I would not ever suggest holding a quad in your hand with props on for testing, at almost face level no less... Esc's and FC's can glitch, a throttle control can get bumped. It does not take much of an accident for that quad to jump out of your hand and bite you, and those spinning blades have much more force behind them than you think.  I have two scars on my chest to back that up.

        What happened? An esc glitched and one motor went to 100% throttle instantly. Your reflexes are not physically fast enough to react to something like that. be safe.

        • Yes... your right... not the smartest move I agree. 

        • Sounds to me like another YES vote for a one-motor-at-a-time real time vibration motor test app...  :)

      • I always use my flight stand I made out of some old wood and PVC pipes. MUCH safer than holding on to it :)

    • Moderator


      ++1 That would be a fantastic idea! A simple utility that could loaded and run on the APM/Pixhawk, connected to Mission Planner etc. allowing the user an interface where they could enable and run individual motors at a specific user select-able output level from 0-100% repeatably.The sensors of the FC could be used to gather the information and Mission Planner could then display that information, allowing the user to dynamically balance/diagnose each motor/power system in a safe and easy way.

      Vehicle vibrations are such a major cause or contributor to the erratic behavior of flight controllers, that this seems to me to be a no-brainer. I think this should be as fundamental as calibrating the compass or accelerometers.

      We have utilities built in to Mission Planner to accomplish each of those tasks, why not one to check vibration levels during setup or after a crash for each individual motor? The more I think about it the more I think this is something that not only should be done, but must be done!

      Great idea Patrick!


      Nathaniel ~KD2DEY

      • So, How do we make this happen?

      • Glad to hear an enthusiastic response!  :)  I would run an app like this before and after most every flight.  I hope this thread catches on...  

      • +100 ON THAT ^^^

        this would be a huge beneficial feature. as it is, one cannot even test directly in MP if the motors are oriented correctly for the chosen frame / model.  the motors tab (IMHO) needs a serious overhaul.  the "ABCD" generic layout should be re-labeled 1,2,3,4(5,6,7,8..etc) in exact layout relation to the configured model and FC pwm output channels.  this way one could not only confirm correct motor hookup, but also know which motor is expected to spin up during a test.  fwiw :D

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