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 –


  • just a feedback...I flashed the firmware, I haven't changed anything on my setup, just the firmware. Upon flashing, I cannot control my Alexmos gimbal's pitch. The Alexmos board is connected to the Aux1  port of Pixhawk which is programmed for the tilt control. It was working on AC3.2.1 before, but after flashing, the problem was there. I reverted to AC3.2.1 and again I can control the pitch. I tried to reflash AC3.3rc1 afterwards, but the problem persists. I used to control the pitch via RC6, the Gimbal is configured before in AC3.2.1, Can you help me please?

    • perhaps I need to rewire my gimbal to pixhawk... Can somebody enlighten me about the serial interface? i believe I am using the PWM setup, with RC9 (Aux1) connected to the Alexmos gimbal RC_pitch.. 

      Or it would be better if I can still use PWM for the RC pitch of the Alexmos BGC..

      • Anyone else having this problem?

  • WARNING to TradHeli users:

    Do not attempt to fly AC3.3 until you hear otherwise from me.  I have not even bench tested it yet, let alone test flown it.  There are quite a lot of changes that have gone in that could be crash-o-matic for helicopters.

    AC3.3 release for Tradheli is likely to be delayed.

  • Upload Copter 3.3 to replace the 3.3 dev (debug bad accel health, but IMU2,Dropix, etc,etc...)

    Needed 3 upload to manage the 3.3 installation.

    Seems to work great, little windy day (5Km/h), auto-tune is great, same result on the PID as VP Kuisma and others but seems to work fine, the Quad is fun to fly, even if, for the moment, only one battery for auto-tune and PosHold and...RTL

    aggressive PosHold flight is great.

    I'm really happy with the Ardu, great work! far away the best!


  • I'm looking forward to trying the 'new and improved' Auto Tune; just finished a quad that's a bit overpowered and wobbles like a weeble on descent. 3.2.1 AT gave some crazy results.


  • Re: "require the vehicle's accelerometer calibration to be done again" If I go up to 3.3 rc1 to do a test, when I go back to 3.2.1 to operate will I need to also redo the accelerometer calibration so it's compatible with 3.2.1? Or, having done it once with 3.3 rc1, is it good for 3.3 rc1 and 3.2.1?

    • Developer


           The accel calibration values are stored in different eeprom locations for AC3.3 vs AC3.2.1 so as you switch between versions, you'll see the accel calibration values switch to what they were when you last calibrated the accels using that firmware version.  So once you've done the accel calibratoin for AC3.3, it should be safe to switch back to AC3.2.1 without having to re-do the accel calibration again.

  • Is the increase in the number of Do_Jumps permitted from 3 to ? included in this release?

    • Developer


      Yes, the max number of do-jump commands has been increased from 3 to 15 for the pixhawk boards in AC3.3-rc1 (and higher).

This reply was deleted.


Shivchand Jaysaval liked Shivchand Jaysaval's profile
Aug 25