ArduCopter 3.2 ready for wider use

After months of testing, ArduCopter 3.2 (aka APM:Copter) is ready for widespread use and we invite all users to give it a try.  In order to manage the support load at first it will be available only through the Mission Planner and APM Planner2's Beta Firmwares link.  This link is visible from the regular "Install Firmware" page if you check the "Advanced View" on the Config/Tuning >> Planner page.  On APM Planner2 the "Advanced View" it is under the File menu.

In about two weeks we plan to replace AC3.1.5 with AC3.2 as the default version dispensed by the ground stations.

The full list of changes can be found in the ReleaseNotes but here are the highlights:
Flight Mode Enhancements:

  • PosHold flight mode: similar to Loiter but with direct response to pilot input during repositioning
  • ACRO mode handling improvement EXPO (for faster rotations)
  • Drift mode uses "throttle assist" (similar to AltHold)
  • Smoother transitions between flight modes (i..e when entering Loiter or RTL from high speeds)

Mission Enhancements/Fixes:

New Sensors/Devices:

Safety Features:

  • EKF/DCM check will switch to LAND mode if heading error > 60deg for 1 second
  • Baro glitch detection
  • Pre-arm check for Gyro calibration success
  • Pre-arm check that internal & external sensors (gyros, accels and compass) are consistent (Pixhawk only)
  • Parachute support (Pixhawk only)
  • Feedback to Pilot when taking off in AltHold, Loiter, PosHold (i.e. motors spin up a little as throttle is raised)
  • EKF (new attitude and position estimate system only used for reference in this release)

Bug Fixes:

  • Pixhawk GPS driver buffer overflow that could lead to missed GPS messages
  • Pixhawk I2C bug that could lead freeze up if I2C bus is noisy

Known issues/Warnings:

  • Pixhawk users will need to recalibrate their compasses
  • PosHold won't show up as option on FlightMode screen if you have an old version of mission planner.  Please select Help > Check for Updates
  • Landing detector is more strict meaning it may take longer to disarm after RTL, AUTO
  • Set THR_MID parameter especially if you have a very powerful copter because "Feedback to Pilot" raises throttle to 1/2 of THR_MID
  • Spline twitches slightly as it passes a waypoint especially if WPNAV_SPEED is set > 500.
  • Dropped support for NMEA and SIRF GPS on APM boards (ran out of Flash space)
  • Dropped ssupport for sonar for MultiCopters on APM1 and TradHeli on APM1 & APM2 (ran out of Flash space)

If you hit issues, please post them in the APM Forum and include a dataflash log file if possible.

Special thanks the Marco and the Beta Testing team from the AC3.2 beta testing thread who put their copters at risk in the pursuit of a smooth, safe release.  Here are links to some of their videos: Marco's DJIs900, Holger's Water Tower, Josh's Acro, Ray's TradHeli2&FPV, Raph's Hawaii, PhillS's CommandYawThor's Zombie Run&FollowMePhanivyas's Test, Rob's TradHeli, Christian's Test1&Test2Balloon's Spline, JimJ's FPV, Ultrojo's ROI & Spline&FollowMe1&FollowMe2, Troy's Mission

Thanks also to the code contributors to this release including Tridge, Jonathan, Leonard, RobL, Paul Riseborough, MichaelO, Julien Dubois, David Dewey, Andrew Chapman, Emile, Allyson and many more.  If you want to get involved check-out our dev wiki.

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  • @Todd - I only used PosHold once so others here will be able to give you better feedback. But to answer your question, I didn't notice any difference with hands off between PosHold and Loiter. The copter was locked in place and was quite stable. From my little play with PosHold it felt/behaved a bit more like what DJI controllers feel like in their 'GPS mode'. There was a small breeze when I was testing so it was doing a very good job at staying in place.

  • Thanks Darrell Burkey,

    Im curious to know what the difference between Position Hold & Loiter when not touching sticks?

  • Developer

    @Todd, there shouldn't be any need to re-do the autotune with AC3.2.  The PID gains should be pretty much (or exactly) the same as AC3.1.5.

  • Developer


    I think that was from Tridge (arduplane) who added the additional 3rd compass support after testing some prototype Pixhawk boards with the 3DR hardware people.  We should probably remove it because there's really no way to access it physically at least on the existing boards.

  • I've now flown 3.2 on a micro 250 (Pixhawk), a 3DR quad and a 3DR hexa (both APM 2.6). I haven't tuned any of them yet so just using the defaults. Gave stabilize, alt hold, loiter and land a good fly around with no issues whatsoever. I gave PosHold a go as well on the hex and it was fantastic. I really like it. Thank you so much to the team for your hard work. I can't wait to try out some of the more advanced features and to get some more experience with 3.2.

  • @ Rob  Lefebvre.

    Thanx for the clarification

  • Moderator


    Thanks for the reply. I understand the part about the I2C bus, but why do we then have compass3 parameters?

    Best Regards,

    Nathaniel ~KD2DEY

    (Just trying to understand the parameters)

  • Developer

    @John Anderson,

    I think those compass offsets will be fine.  The 2nd one is the internal one and we know the pixhawk board itself causes that compass's offsets to be larger.  With an external compass attached the internal one will never be used (even in case the external one fails).  With AC3.3 a fail-over to the internal will happen but that's a ways away still.


    There are some changes to the attitude control but they're pretty subtle so I wouldn't expect many people to notice.  We originally add a feed-foward to the rate controller but it's off by default for AC3.2.


    There's an internal compass which appears as compass2 but there's physically no way to connect a 2nd external compass to the pixhawk.  To get technical, the external compasses we use (HMC5884) have a hard-coded I2C address.  This means they must be connected to different I2C buses.  There is a 2nd I2C bus on the pixhawk but the pins aren't exposed so you can't plug anything into it.

  • I WISH the arm/disamr routine was FASTER LIKE NAZA... i dont understand why the aom take s5-6 seconds more than NAZA. NAZA is immediate and safer.

  • So far AC3.2 RC14 is working great, looking forward to test AC3.3 RC-1.....
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