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!

Views: 374469

Reply to This

Replies to This Discussion


For the GPS issue, as part of setting up the optical flow sensor did you set the EKF_GPS_TYPE parameter?  If yes, maybe setting it back to "0" might get it working again.

I had changed the EKF_GPS_TYPE parameter back to 0. It failed to even show stats about the GPS, i.e. Sats, hdop, etc.... After that didn't work, I actually went one step further and used a beta param file I saved from before I configured the OF, when the GPS was working, and reloaded that. No dice. Even reflashing the firmware to the same beta firmware didn't help. The problem only resolved when I reflashed to 3.2.1. I will see if I can get the logs for you.

I agree with Thorsten that it's likely caused by the buzzer.  At the moment that the vehicle switches modes the Z-axis accelerations on the two IMUs separate.  The MPU6k thinks it's falling, the lsm303d thinks it's climbing.  This is the 3rd incident of this now, makes me think we need to change the tone of the buzzer.

just remove the buzzzer :) 

in any case we receive all the relevant info via telemetry either on  MP or tower... 

after more than a year of using pixhawk I can say that buzzer is more of an annoyance than help. 

I removed it on the third day and never used on any subsequent  installations.

p.s. I do not use safety button either :) 

A picture of the buzzer mounting distance from the pixhawk in the attachments.  Its a little disassembled but I'll put it back together the way I had it and test it without the buzzer connected.


Thanks Marco,

   Maybe  "out of sync" was a bad term. Very twitchy is more like it. If I reload the previous parameters from the 1" smaller props, it's better.

I've seen others speak of settings to try prior to AT

The motors are KDE 2814XF-515. AUW is 2679. 14x5.5 Gemfan CF is slightly over powered, 15x5 T-Motors are more.  It's just odd that after AT it behaves so badly; never had such a difference.


     I'm using those same motors with 12" carbon props and Afro 20A ESC on a 6S and they tend to get slightly warm lifting 3500g AUW. I can only imagine the power being put out with 14in Carbon blades. Are you using a 6S also?

What brand speed controllers are you using?

Lowering those settings i mentioned worked wonders getting mine stable. Hope you figure out whats making yours act weird.

I didn't see your post....thanks, that's what I recall reading but it got lost in the posts...will definitely try that.  The copter is using HobbyWing Quattro 4-in-1 ESC......best ones out of 4 tested.

I've used several different props depending on AUW and just plain experimenting, but not 6s....it's actually less efficient than 4s on these motors.

With Gemfan 14" CF, AUW 2679, the quad will hover over 40 minutes @3.6v lowest cell on landing with 16A Lumenier 4s battery. g/W=9.3 which is way above eCalc's estimate of 7.39 as is the hover time. I think it can touch 10 with enough tuning etc. Tarot CF props were horrid (flexing).

APC 14x5.5 drops to 8.7 g/W, but the weight is 2770 due to the adapters.  

The motors barely get warm with either, and the copter scoots punching the throttle. With a 12A battery it really goes. With 8A and smaller props it flat out screams.


The Spy 750 Y6 it also has the 515's (HobbyWing XRotors) with T-Motor 15x5. Plenty of power to spare and cool as a cucumber. The most stable prop combo was Xoar 15x5 top and 14x7 bottom (bought 14x8 also but chipped one so didn't try them), and very steady on fast descents.  However, the T-Motors have so far been the most efficient. 

Here's the vibration levels with the Gemfans

But it took a lot of work to get those Gemfans balanced LOL (yes that is solder wire embedded in super glue soaked velcro).

Bottom line is the T-Motor's are no heavier than the Gemfans, so I think the AT has changed from when originally done and now I need to massage some settings to get it right. It's only a temporary install anyway, but would like it to fly decent before switching back. If I put the 14's back on and it still flies funky after a new AT in rc8, no doubt in my mind it is changes in AT.


I had a similar issue with the proximity of the buzzer to the Pixhawk. Thorsten and Randy identified the problem (I moved the buzzer a few inches). Note that the problem of interference between buzzers and gyroscopes is being studied. See here: http://www.cio.com.au/article/581231/sounds-can-knock-drones-sky/

HI Devs,

Has something changed with MAVLINK from 3.2.1? I have a an app that works perfectly on an APM3.2.1, but on my PIXHAWK running 3.3rc8 it doesn't get the correct descriptions for the flight modes; although it will still switch them.

Any thoughts?

Cheers, Mike


what is interesting is that it seems not to be direct vibration in this case. In one of my logs I saw the buzzer tone in the mag data. So maybe it is magnetic interference. Or sound pressure - which is vibration again...

It gives you additional safety. Depending on the telemetry allowed you can have signal loss from time to time. And in this case I am happy about any buzzer response.

Reply to Discussion


© 2019   Created by Chris Anderson.   Powered by

Badges  |  Report an Issue  |  Terms of Service