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!

You need to be a member of diydrones to add comments!

Join diydrones

Email me when people reply –


  • Developer

    Robert, Winston,

    Very sorry about your crashes.

    I've looked at your logs and it looks like the EKF's coming up with bad attitude estimates for roll, pitch and yaw - or at least they inconsistent with the older DCM by >10degrees.  This is likely what's causing the out-of-control feeling you're getting.  Obviously this is pretty serious so I've posted a warning above to ask people to stay on -rc5 until we figure out what's going wrong and publish fixes.  Worst case we will roll-back to -rc5 until we figure it out.

    RobL had an issue with his helicopter as well and during that analysis Paul mentioned there was a change in the gyro offset learning - that would be consistent with this problem.

    3702036870?profile=original3702037015?profile=originalReally sorry again, hopefully this will help us get to the bottom of the problem soon.

    • Yes, something is badly wrong! If you plot the learned offsets against the compass inconsistencies you can see that the learned offsets vary hugely and almost randomly. You can also see that the inconsistencies rise with the variation. (I'm not sure if it's relevant but I see a similar oscillation but on a much smaller scale with rc5 and EKF_GBIAS_PNOISE set to 10x it's default)


    • Risk of early adopters - thanks for the explanation.
    • Thanks for the warning, Randy.

      I can't locate the link for the manual download of -rc5 for the downgrade.  Are you able to advise how to obtain it?

      • Developer

        We haven't stored the -rc5 binary anywhere (we have the source code though of course) and there's no easy way for me to revert the MP's beta version without yanking someone back from their day off so I'm afraid it's going to stay with -rc6 at least until tomorrow.  I just hope that people see the warning and are very careful or don't upgrade.

        • Many thanks for your explanation and for the very fast fix. I will go on with RC7 tomorrow. I did serveral flights with RC6 without any issue (4 flights with about 80 min flight time). I realize that every RC has a risk to use.

      • Same problem for me. For safety reasons it should be better to make only RC5 available through MP, or if you found the issue release RC7.

    • Thanks Randy
  • Hi!

    Yesterday I was testing ArduCopter3.3-rc6, after having upgraded from ArduCopter3.3-rc5 (with this firmware my Quadx remained stable, with good attitude and great consistency against the force that produces wind).

    First flight performed,

    I clearly saw that my quadx completely lost the tune, not stabilized, not attitude and very loose. I have tried to adjust it and do not get good results.

    Second flight,

    I changed the values of the following parameters:

    "INS_ACCEL_FILTER" = 42, changed to 20.

    "INS_GYRO_FILTER" = 42, changed to 20.

    With those values and flying in the AltHold mode, the quadx showed a very strange behavior, I lost control of the quadx, did not respond to the Throttle of the radio control and couldn't land it, so I had no more choice that impact it with a wall so stop.

    The damage was not severe.

    I returned to the Arducopter3.3-rc5 version, and everything is working well.

    2015-06-26 18-43-42 11.bin

    • Well, EFK2 error and LAND failsafe from very early ... similar to my error in the post above.

      Would you mind sharing the rc5 link please?

This reply was deleted.