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

E-mail me when people leave their comments –

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

Join diydrones


  • Hello Randy,

    Did all the following:

    Upgraded from v3.2 to v3.3
    Recalibrated Accel
    Recalibrated Compass
    HDOP from 0.8 to 1.1
    Sats from 10 to 13
    3DR Compass and Mag

    Rebooted after upgrade, and rebooted after recalibrations.

    Will not arm, messages displayed, Prearm Waiting on Nav

    Any ideas?

    Log attached.

    Dropbox - Error
    Dropbox is a free service that lets you bring your photos, docs, and videos anywhere and share them easily. Never email yourself a file again!
  • Hi Randy! I have been trying to get the sbus output to work today but I had no luck. I have a X8R and when I conect my Storm32 controller directly to the receiver I have no problems but when I try to do the same on the Pix I get no response. I have set the BRD_SBUS_OUT to 1 but still nothing. Any clues?

  • I put 3.3 on my X8.
    It flew fine but I notice it is hunting around a bit more than what it previously was on 3.2 in a hover.
    Could this be improved by trying to tune the EKY tuning settings?

  • correction: ardupilot documentation is updated, configuration changes are just sprinkled throughout the docs.

  • We really need an "Upgrade Checklist" in APM Planner that lists whatever recalibrations a pilot needs to do after a new firmware is installed. the ardupilot documentation doesn't mention any of these and there's no indicator anywhere in the mission planner that accelerometers need to be recalibrated.

    Looking forward to a test flight on 3.3. Nice work!

  • Developer

    @Ron, yes, feel free to go straight to Copter-3.3 for new builds.  That warning was there during the beta testing phase just to help us separate the frame issues from the software issues.

  • In the 3.3 beta thread, there is a warning to make sure your copter is flying well on 3.2.1 first before trying 3.3 beta. Now that 3.3 is an official release, can we go straight to 3.3 without first installing 3.2.1?

    I was building a new hexacopter today and planned to load 3.2.1 but the 3.3 release caught me by surprise.

  • great job, big thank you to all supporters


  • Developer


    You'll need to re-do the accelerometer calibration but shouldn't need to do the compass.  If you have problems with 3.3 then if you could post the dataflash log into the APM:Forum we can have a look.  If the issues you've been having are hardware related then it's unlikely Copter-3.3 will fix them but if it's vibration for example, then it might fly better.

  • thanks you randy, i'm sick with 3.2.1 i don't know it's fault or something wrong... i will update 3.3 today or tomorrow and test. should i need to re-compass and accels. ( do i need to choose 3dr iris+.param ) ?

This reply was deleted.