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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            • They are a bit of a pain to solder up but I really like how easily they disconnect.. Never had any problem with them. 

              • I find them easy as long as you pre-tin just the hashed end of the gold tab and the wire you're using. If you go over that hashed area, or the wire gauge is too heavy then they just never go into the housing.

  • A testament 3.3 beta.  8 days of mapping at 7 to 8 hours a day.  Countless hours of flights without a glitch.  Pretty much all auto missions.  I'd say it's ready for release!  Lets get some lidar terrain following in 3.4beta now : )  Terrain data doesn't do me a lot of good when a mine site has change in the last 6 month lol!   So beyond the 3.4 wish list, awesome job on 3.3! 

    • Developer

      Cool, thanks for the report!  We're planning on making Copter-3.3 the default version from the MP (and other GCSs) some time this week.

      • Congratulations to you and the Dev team! You did an amazing job.

    • +1!
  • Just had a very fun afternoon at a friend's farm with my 3DR X4 and QAV250, both running 3.3RC. I have taken advantage of IMU_USE to switch off my second dodgy IMU on my pixhawk and I have to say the results of that + 3.3RC + M8N are astounding. Absolutely rock solid. FPV was a delightful experience - I felt confident to go pretty much anywhere and everything worked 100% perfect. It was quite an eye-opener to compare the peformance of the M8N on the X4 with a 3DR LEA-6H on the QAV-250 - night and day in terms of stabilty, position holding etc. The QAV flew very well as well and was a lot of fun. Kudos to all concerned with the 3.3 development.

    • Developer

      Hi Andy,

      Good to hear people are starting to use arducopter on the 250's!! I am glad you are enjoying it!!

      • Hi Leonard - all thanks to you :)

        I'm interested in your COMPASS_MOT values. For the internal compass I have values of 50 on the X & Z access. Yes that's 50. Yours are much lower and yet this is the same frame. What could be generating so much interference? Could it really be the ESC's? I've carefully twisted all the motor wires, so I'm a bit perplexed.

        Even on the external I have values of around 5 for X & Z which still translates into something largish at 20 amps.

        • Developer


          I haven't seen your parameter file but I just wanted to check that you're not using the throttle based compassmot.  The throttle-based method (as opposed to the current based method) uses a different scale so the numbers appear much larger.  The thr method is also much less reliable because the compass interference is linear with current but not linear with throttle actually.  We're planning on removing the thr method for Copter-3.4.

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