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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              • Can you explain please? As I can see via IMU/IMU2 vibration is acceptable. 

                • T3

                  The IMU data is based on filtered accelerometer data, whereas the vibes are calculated on the raw IMU data.

                  Also your Acc data are (randomly; at least not related to pitch roll and yaw) increasing heavily. And since there is clipping you definitely have too high vibrations.

                  The best way is to look at all these data (IMU, Vibes and clipping) and to use the worst for interpretation.

                • T3


                  you should look at the Vibes messages (see: for more details).

                  As Rob mentioned the vibes are "extremely, extremely high" on your copter - they go up to 120. Normally it should be below 30. Below 50 should be ok. Depending on the damping system, the balancing of the props, and the frame setup it is possible to get the values below 10 even for larger copters (for in Loiter the vibes on one of my copters are < 5). 

                  I suggest to change the damping system and to carefully balance the props/motors.


                  • But IMU AccX, Y, Z level acceptable (IMHO). So I don't understood why IMU vibes good but VIBE section are bad. 

  • Have tested from rc1 still have the very same experience that position hold is behaving strangely (1) unreasonable rapid roll movements (no wind) after switching from Loiter (2) very bad breaking performance even with max settings (angle/speed of change).


    [cannot upload logs due to size]


    • Developer


      No much has changed in PosHold vs AC3.2.1 but it's certainly possible that it's been broken somehow.  Have you tested AC3.2.1's PosHold with the same parameters to see that it performs better?  I'd just like to confirm that this is an AC3.3 issue instead of a general PosHold performance issue.

      • Randy - you might be right, I did not use/test position hold intensively before 3.3 so I am not sure. Due to the nature of problems (copter movements) I assumed it is EKF related but it is assumption only.

  • Hi all, quick question if I may.

    Since upgrading to 3.3rc8 I'm having problems connecting via the radio telemetry port. I no longer get the flashing red LED on the air side half of the pair. I thought the receiver had failed and purchased another one. But this is the same.

    I can roll the firmware back to v3.2.1 and everything works fine but as soon as I revert back to 3.3rc8 it refuses to work.

    I read this thread daily and don't recall any notes about this so I thought I'd ask.

    Any ideas?



    • Mark,

      I'm going to assume here that you are using telem1 for your radio.

      If you connect your telemetry via less than 6 wires, IE, your radio doesn't have or doesn't connect RTS/CTS and if you have BRD_SER1_RTSCTS configured for automatic flow control (2, the default), then you have encountered the bug I reported here:

      This bug was present in the code for older releases, but seemed not to manifest there.

      You can work around the bug by setting BRD_SER1_RTSCTS to 0, no flow control.  Please let us know if this is your problem.

      I submitted a pull request 3 weeks ago which fixes the bug and also vastly reduces the time required to detect the lack of flow control, but so far the developers do not seem to have had time to review and merge the fix.


      • Thanks for the replies gentlemen,

        The problem was fixed by Brad's suggestion. Working on 3.2.1 but not on the latest really confused me.

        I really appreciate your help.



This reply was deleted.


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