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


  • Hi,
    Wasn't EKF present at 3.2.1? I saw the EKF text in the HUD, with AC3.2.1
  • Hi Fnoop, thanks, I'll try posting there too.

    The foam hasn't caused problems before - I previously had it mounted using the thin (3mm?) foam that comes with the pixhawk but found vibrations were far too high, especially in the z (vertical) axis, and it couldn't do any of the auto modes (loiter, alt-hold etc) reliably. The gimbal is unrelated - it carries an HD camera. It's well isolated from the frame with both foam and rubber ball mounts, but I think it is still either managing to get vibrations into frame, or causing EM problems. I'm assuming the logs will tell the full story to an expert (hence posting here!) but I just don't really know where to start, or what "normal" logs look like in comparison.

  • @Andy - At the risk of involving a third forum, this might be a better place to ask rather than a blog post:

    You say you've got the pixhawk on a bed of soft foam - this is often not a good idea as it disconnects the IMU somewhat from the frame and can make it difficult to react properly to movements.  A gimbal is usually completely hung on springs(/balls) and further exacerbates the problem.  Try mounting your pixhawk on something a bit firmer  - the two-plate-separated-with-balls seems to work well, or some firmer foam squares, and see if that helps.

  • Hi Randy, I wonder if I could ask for some help. Since adding a cheap gimbal, I've been seeing EKF errors, and wild uncommanded movements. I've described it in more detail, with a video and link to the logs, here:

    Is there any chance you could have a look and see if there are any obvious pointers, or anything I could do to sort it out? I'm new to the game, and relatively out of my depth!

    Many thanks, Andy

  • Hey Randy,

    I'm wondering if you can answer me the following. Say I'm flying in a non GPS mode and my GPS is picking up essentially bad data and thinks I'm somewhere I'm not. As long as I stay out of the any GPS mode will any GEO Fence or fail safe kick in? I often do some indoor flights and don't use GPS however It is left connected.

  • here is the logs

  • hi Randy

    I just change new pixhawk to my iris+ and setup fw 3.3.1 and calibration all. When i fly with loiter mode and i change to mode alt hold. Iris+ is not hold high and its fly up about 4-5 feet. And when i back to loiter then its not hold high. Then it drop high like before i switch loiter mode to alt hold. Can u let me know what happen ? Thanks you.

  • Hi randy.
    I just change new pixhawk to my iris+ and setup fw 3.3.1 and calibration all. When i fly with loiter mode and i change to mode alt hold. Iris+ is not hold high and its fly up about 4-5 feet. And when i back to loiter then its not hold high. Then it drop high like before i switch loiter mode to alt hold. Can u let me know what happen ? Thanks you.
  • Does anyone know if there will be any issues using Mission's Planner geotagging function with the logs generated by 3.3? I was caught out by this when updating Ardupilot and just want to make sure before I update my hexa and I use it to do mapping with a Sony camera and use Mission Planner to inject the geo data to the exif info on the photos.

  • Developer


    hmm.. not sure about the issue getting stuck loading parameters.  Here are some random ideas:

    • Maybe it depends upon whether you connect using a telemetry radio or the USB cable.
    • make sure to use the latest Mission Planner (see update button on the Help screen).
    • Try disconnecting anything that could also be sending info to the ground statoin (i.e. a MAVLink gimbal like the SToRM32 gimbal or an OSD.
    • make sure to wait a minute after uploading the firmware before trying to connect to allow it time to upload the I/O board firmware
    • check the mission planner's messages tab (bottom right on Flight Data screen) to see if anything is written there
    • get a tlog and post it somewhere we can have a look at it (maybe the APMForum would be best).
This reply was deleted.