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!

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Ok it is not my bluetooth driver's fault, it is indeed a Mission Planner problem of version 1.3.33.

1.3.32 works perfectly.

confirmed. First thought is was my bluetooth driver, but as you are saying, version 1.3.32 works!

Hello, I almost crashed today as my copter went crazy in stabilize mode while trying to position to land. It began to drift hard and I had to steer fully against the drift to catch it again. After estimated 2 seconds, it was stable again and I was able to land luckily. There was almost no wind!

I only see ERR EKF_CHECK in the log. Maybe you can help me find the cause.

I really thought this is almost impossible when flying in stabilize.

Here is the log, please have a look towards the end:


With the next battery, this issue also happened somewhere during the flight in greater altitude. After I noticed it, I switched to loiter, which caused the copter to go completely retard, giving full throttle while flying towards a certain direction. I catched it switching back to stabilize and landed.

Here is the second log containing this:


I had great luck not to crash today.

I really want to know what is wrong with the Pix these days.

I am flying a Hexa with AUAV-X2 board running Copter 3.3.2 stable.

Sunnysky 980kv motors with 10x5 props, 30A escs, Drotek M8N XL GPS on 4s.

Any help is appreciated.

Hi Dave

You're probably better off asking here:


or here:


This thread was for beta testing of the 3.3 code which is long over, even though in the last week or two it even seems to have expanded to general 3.2 and 3.4 questions..

Yes for servo deploy. That means that landing gear is open in start before flight.

Look this page: http://copter.ardupilot.com/wiki/landing-gear/.

Then look the values in this channel(from mission planner radio controller) that use for landing gear and change properly . For fail safe decrease this values .(ex. from 1750 to 1700) .

I solved my problem about the Landing Gear (=

First at all: thank you very much to everyone!

The problem was the following:
Landing gear that opens on copter start up.
Every time I plug the battery the landing gear open itself.

The solution was the following:
Use the Safety Switch.
I had disabled the safety switch.

With enabling it every problem was solved!

You have bad vibrations. Pretty sure that's the cause. Look at clip0/clip1 - it's clipping all the time and your vibe values are very high. Everything in the EKF is struggling - even earlier on in the flight, its only at the end that things get bad enough to cause an issue.

The thing I don't understand is the GyrX offset decreases rapidly at the end. Not sure if this is vibration related or not.

I wouldn't fly in anything other than stabilize with things the way they are - loiter is really chancing it!

somehow, I don't receive the activation mail :(

I also found that out now. But only in Z axis, am I right?

My FC sits in a case and this is mounted on Hobbyking FC mounting foam pads. What can I do to reduce the vibrations further?

I am wondering, why the copter almost crashed although I was flying in stabilize?

Here are two screenshots from the flight where the loiter flyaway occured:

I read in the Wiki, that if the EKF4.SV and SV value is above 1, the EKF stops using the GPS for calculating the position and the velocity.

Now why did it do that? As you can see, I have perfect GPS reception (hdop ~0.7, sats 13+).

Also the Mag failed for some unknown reason:

Shouldn't be caused by vibrations, I think.

Same behavior with the stabilize flight:

I don't understand why the copter behaved unstable despite flying in stabilize mode which has nothing to do with GPS?!

Thanks for your help.

I've always used a pixhawk on the two plate with rubber-thingees mount which has always worked great.  I then tried the hobbyking orange foam that the wiki suggests and it was a complete disaster for me - I got all sorts of barely recoverable control issues even in stabilise mode, so I went back to the two plate mount and worked perfectly again.  If you're getting high vibes it will certainly affect stabilise mode and it's a complicated subject with no single answer, so if you're having problems then try a different solution until you find one that works.  If you're getting clipping and high vibes then fix this first as it will always make your flights unstable, gps is largely irrelevent at this stage.

Thanks for your answer.

I have these mounting pads and thought of switching to the orange latex foam. But as this didn't work for you, I am afraid it won't help in my situation either..

The two plate mounting solution is no option for me because i want the FC to sit between the sandwich plates and there is not enough space for this mount.

I may have to test my motors maybe, as I already balanced my props.


I can help you with FFT analysis to discover resonant frequencies in your

vibration patterns to discover real cause  behind the vibrations.

Vibrations can be due to a number of parallel control data streams interacting each to other.


My fellow student lost his hearing, working as mainframe computer operator due to infrasounds generated by collective sound frequencies by individual mainframe colling system fans, damaging his inner ear mechanics.

So higher harmonics present in such sophisticated electronic gearbox -

processor's clock, PWM clock, flight controlle's clock, GPS clock ( 1Hz, 4Hz or 10 Hz), motor's RPM clock can make such to start generating much lower, infrasonic vibrations ( 1Hz - 30 Hz),

my next guess is moisture build up on platine connectors if you fly at higher altitude for a longer time

to keep stabilize mode to stabilize instabilities (see above) may eat up

100% processor power, make 100% memory busy,

so I would suggest to let Ardu fly your drone in debug mode and have

processor busy, memory free parameters downloaded via MAVLINK to your control station via telemetry.



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