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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@Maciej: just watching the video can't understand if your quad is well tuned, maybe post here your parameters after Autotune.
It seems too soft.

Hello everyone,

@Shaun, this mistake is due to the inclusion of the variable "Timeus" to CAM messages and restructuring of the message CAM data. Note that the variable "Timeus" has been included in all messages, so the messages ATT and GPS are also affected. To fix this, simply adjust properly "offtsets" in the setup screen Geotag Mission Planner tool.

Your configuration is incorrect, with new releases, for ArduCopter, Mission Planner must be set like this:

I hope I've helped.

Regards from Spain,


Round 2....


Sure here are the parameters. It feels much better than the previous autotunes where the quad was very "wobbly" and did overshoot quite a lot.

From google drive


Is there a recommended solution for mounting the pixhawk?  I notice that leonard recommends effectively hard-mounting it (which I'm not brave enough to do), and I can't find the 3dr recommended foam anywhere else except for 3dr (which I'm not suffering the ordering process and costs for from europe).

I've just bought some of the HK orange foam (about £2 incl delivery here in the UK) which I'm going to use to mount my X2. Will let you know how it goes.

on both vehicles with auav I hard mounted their cases and I find vehicles responsiveness and autotune results to be way more accurate and precise.

inside of the case I use a thin layer of soft foam to wrap corners and secure it in the case to prevent direct contact of the board with plastic case, it seems to work fine.

it gives you more pain to tune and balance motors and props, but, it pays off. foam and platforms on bobbins mask the issue but do not fix it, yet, an original 3dr gel is claimed to be quite good too.

Rate Yaw P 0.86??? And i thought mine was high at 0.7 

this looks a lot like nor cal coast, is it? 

No it's the southeast coast of Sweden.

Problem on optical flow with APM rev 3.3rc8 

Dear Friend,
in last week we are testing the APM 3.3rc8 on VR Brain 5.2 , we are checking all nuttx driver and advanced functionality like Optical Flow loiter and lidar terrain following functionality.
So about the lidar we are very happy ... did a lot of test and all work fine as you can see in this video:


After the test of alt hold we start to evaluate optical flow , follow the wiki instruction did the first fight well and check the log ... then activate the optical flow , armed the drone in stabilize , because in loiter the pre flight check tell that is not possible without 3D fix .. then switch in loiter and try to take off. When i'm taking off i check if the command on roll and pitch work well but it don't work ... don't move the drone ... only throttle work if i re switch to stabilize i re take the control on pitch and roll .
What could be the problem ? Are there some guys that sucessfully check this release of firmware with Optical flow ? 
Thanks in advance 

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