Copter-3.3 released!

After months of testing by the beta-testing team and no significant issue during the soft release, Copter-3.3 has been released.  You can load this version onto your vehicle using the Mission Planner or APPlanner2's Install Firmware screen.

As mentioned previously, this version and all future versions of Copter only work with fast CPU boards like the 3DR Pixhawk (and compatible) boards, VRBrain, NAVIO+, etc. Slower CPU boards (i.e APM2.x) can continue to load Copter-3.2.1 from the MP/AP2.

Support issues should be reported in the APM Forum.  Enhancement requests and confirmed bugs should go into the GitHub issues listThe wiki has been mostly updated but if you spot missing items please report them to the wiki issues list.

The full set of changes can be seen in the Release Notes but the highlights are below.

Known Issues/Warnings:

  • users will need to re-calibrate their accelerometers because of 5c (accelerometer range increase).
  • FrSky telemetry users must set SERIAL2_PROTOCOL to "3" and reboot the board to enable FrSky telemetry like in previous versions
  • this version corrects a long standing issue in the HDOP reporting so values will appear about 40% lower than previously but this does not actually mean the GPS position is better than before.
  • TradHeli is still in beta testing so it remains on AC3.2.1 for now.

Changes vs Copter-3.2.1
1) EKF replaces DCM/InertialNav for attitude and position estimation which provides more feedback and robustness in case of sensors failures
2) Control improvements:
   a) battery voltage compensation should maintain control as voltage drops
   b) current limiting can be used to reduce the maximum current requested to reduce strain on battery and ESCs
   c) air pressure compensation should reduce need for re-tuning when flying at different altitudes
   d) improved throttle curve should reduce wobbles during descents
3) AutoTune for yaw
4) Cameras & Gimbal improvements:
   a) SToRM32 gimbal support
   b) do-mount-control mission command allows controlling absolute camera mount angle during missions
5) Vibration resistance:
   a) real-time reporting of vibration levels by clicking on Vibe field on HUD (also recorded to logs)
   b) noise weighted average of accelerometers used to weight IMU towards the one exposed to less vibration
   c) accelerometer range increased from 8G to 16G to allow use in higher vibration environments (i.e. reduced "clipping")
6) Other:
   a) improved landing on slopes
   b) retractable landing gear support
   c) channels 9 ~ 12 can be used as auxiliary switches (like ch7, 8)
   d) PX4flow (optical flow) support in Loiter
   e) Brake flight mode (stops vehicle quickly but requires GPS)
   f) allow GPS, Telemetry, SToRM32 gimbal to be connected to any telemetry/serial port
   g) Lidar-Lite V2 support
   h) bug fix to RCMAP - remapped channel's MIN, MAX were taken from incorrect parameters meaning all channel ranges had to be the same
7) Tricopter tail servo parameters (MOT_YAW_SV_MIN, MAX, TRIM, REV)
8) Safety items:
   a) crash check triggers with 30deg lean angle error (for 2 sec) even if pilot's throttle is non-zero
   b) modified pre-arm checks to ensure good quality GPS and compas data
   c) lost copter alarm (hold both sticks down and right)
   d) motor interlock & emergency motor stop features on auxiliary switches (ch7 ~ ch12)
   e) RTL_CLIMB_MIN parameter allows forcing vehicle to always climb a few meters at beginning of RTL
   f) LED flashes green quickly if disarmed with 3D lock and SBAS

Thanks to Marco and all the beta testers who risked their vehicles so we could iron out issues and ensure a more reliable firmware for the wider community. Here are some of their videos:

ChrisN #1, #2, Paul Atkin #1, #2, #3, Gervais #1, #2, #3, Gleb Falaleev #1, #2, Pomaroli, Michael, Robert Baumgartner, De Le, Robert Baumgartner, Robert Navoni, Maciej Karpinski

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  • i just update and test fly with 3.2 - 3.2.1 and 3.3 new fw. the frist look, 3.3 is great. i have not test auto waypoint and follow me mode, if some one already test, please post here...

    Hover is very good improvement, but the gps mode 3.3 is not better than 3.2, maybe it will affect the gimbal but in return the thorllte frimware 3.3 is very great, i really love it.

    every new few is more good. i hope randy team is fix gps mode as soon. thanks randy team very much to share for public !

  • I finally flew 3.3 today in WINDY conditions and wow a major improvement over 3.2!!!!!! I couldn't believe looking at the trees bending over and looking at my quad just sitting there almost motion free. Cant wait to try some auto missions and see if the transitions between WPT's is a bit smoother... every version gets better and safer. Thanks Devs!!!! 

  • Drone Crash due to GPS Glitch.....

    Today reactions of drone when gps unconsistency occurs is max lean angle.....quick acceleration, high speed...

    So beginers that fly at 20/30 meters of wall or tree, don't have reflex to toggle althold mode to recover drone.

    EKF filter detect this unconsistency (we can see it through EKF STATUS on MP), but today it's impossible to set it to trigger ekf failsafe for auto invoke alhold or land....As I can see, trigger in this case is disabled (hardcoded)

    I don't understand, all it's done....

    Hope that you will launch another release soonly activating failsafe toggle to althold or land when EKF filter trigger gps unconsistency. As is suposed to do, like for mag issue...

    You can see details here:

    Also I can post video regarding reactions of drone when unconsistency of gps occur if you want.

  • Hi Randy. Can you check my post regarding SBUS output. I have been trying to make it work but so far no good. Thanks

  • Randy,

    Completed the accel recalibration, using the first option tilting/moving in all six planes, and resolved the bad ahrs issue.


    Now for auto-tune.  Frame is DJI S900 and taking off in Stab seemed much smoother even with the CG being off.

    Again, GREAT WORK!!!


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  • Developer


    Yes, there are a number of pre-arm and in-flight checks done on the IMUs and the EKF should switch over to use the good one in case of a failure.  If it's the MPU6k that fails (which was what was happening because of that manufacturing problem) the sensor driver actually tries to restart/re-configure the sensor although it doesn't always work.

  • Randy,

    Will do the recal as well.  The accel recalibrations used were the simple, sitting level recalibration.  Will do the first one at the top of the list instead of the simple, second on the list, as well as reset the logging.

    One other question.  Are there HW checks done on the IMU's and if so, does the information get consumed by EKK/AHRS?  I ask as there were Pxhwks that were shipped up until Feb 2014, which had some IMU's that were suspect.  This Pxhwk was purchased prior to Feb 2014, and curious to know if this could affect the bad ahrs error message, and secondly, if one of the IMU's is/goes bad, will the EKF take the failure into account?

    GREAT JOB to you and the entire team!


  • Developer


    PaulR had a look at it and says it's because there's a big accel bias on the MPU6k which suggests something went wrong during the accel calibration.  Could you try redoing that?  We will try to improve the pre-arm-check failure messages for future releases (issue raised here).

    3702108920?profile=originalBy the way, the pic above shows the difference in the accelerometer values reported by the primary and secondary accels.  They're quite different!

  • Randy,

    Will reset to bitmask and upload the log after.  Initially, indoors with hdop at 1.49 and sats at 10.  Moved it outdoors, rebooted, hdop at .8 and sats at 12/13.  Is EKF only related/use GPS or does is consume IMU data as well?

    Waiting for a post approval on APM:Forum.  :)

  • Developer

    TimV, I don't see anything super obvious so I've asked Paul to have a look (that message normally comes as a result of the EKF not being happy).  Are you trying to arm indoors or outdoors?

    It could be the GPS which seems to be missing about 30% of messages, it could just be a logging issue though. Could you reduce the IMU logging from IMU_RAW to just IMU?  that means changing LOG_BITMASK to "131070".

    By the way, it would probably be better to post support Qs to the APM:Forum.

This reply was deleted.