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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      • Thanks for the response and hard work put in by you guys into the community. 

  • Hi there,

    Im trying to add px4flow(Lucas-Kanade method custom firmware) to pixhawk(3.3rc1) I think, Its work :)

    I have two question about that;

    1) Can I use Mission Plannner's user items "opt_m_x" and "opt_m_y" for optical flow checking?
    2) Which flight mode support optical flow? loiter, poshold, althold?

    • Hi guys,

      I use px4flow with this firmware ( to pixhawk(AC 3.3 rc1) by i2c.

      But it doesn't work. opt_m_x and opt_m_y are always zero.

      Did i miss something? 

      The i2c address should be changed?

      sorry for my English.

      • can you try  power up by USB first.

    • Developer


      Yes, optical flow should work although some more changes are coming to make it more reliable.  It was demonstrated at NAB with the solo.. it's all the same code.

      Only Loiter uses optical flow at the moment but that was a specfiic choice only because it's very new functionality  I expect we will extend it to other flight modes like RTL in the future (it's very easy to extend to other flight modes).

      Yes, I think the opt_m_x, y should show the raw output of the sensor.

      • Hi there,


        Im trying to add px4flow(Lucas-Kanade method custom firmware) to pixhawk(3.3rc1) I think, Its work :) 


        My question:


        1.Use USB connect PIX : I can in Mission Plannner's user items "opt_m_x" and "opt_m_y" for optical flow .

        2.Use Battery powered : Can't in  Mission Plannner's user items "opt_m_x" and "opt_m_y" for optical flow.

          But only reset PIX . I can in  Mission Plannner's user items "opt_m_x" and "opt_m_y" for optical flow.

  • I am waiting for the uploading the 3.3 rc 1 from the MP. WHEN is this ready?

    • Developer


      It's there, just click the beta firmware's link on the MP's install firmware screen.

      • Hi Randy, when I look at beta firmware´s in MP than I see only the 3.2 !!!

        • Developer

          Yes, I also see V3.3-rc1.  Maybe try updating your version of mission planner.  Also you must be using a Pixhawk but that shouldn't matter because the MP doesn't know what board you have when it's not connected.

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