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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Yes, definitely antenna at this position jamming both GPS and compass.

Just screw it below the body under the battery. And move the GPS/compass pole at the place of the antenna, just behind the camera. You should keep the sensors away from all antennas.

I agree that 1.3Ghz could be wreaking havoc BUT having just been through this myself I think another highly likely option is the camera and video cable - neither are shielded and on my mini quad they were completely killing the GPS (vtx had no impact but that was on 5.8Ghz). I have what looks like the identical camera and I believe it leaks a lot of RF interference. Likewise the cable. Wrap both in copper tape and and that should make things a lot better. I would not advise putting the GPS above the camera for this reason - you would be better off moving it to the back. If you look at a fat shark camera setup the cables are always screened.

See here:


Could try connecting to ublox ucenter and doing a cold restart, then let it run for a while (30min?). I've had that help on big deviations.

What hdop and # sats are you getting?

A USB software defined radio is a good way of diagnosing interference. They can be had from ebay for $12-16. Then download some scanning software and do a scan from say 1550 to 1600mhz and see if there's anything showing up around 1575 (where gps operates). If you do get interference, disconnect one item at a time (a process of elimination).

These are all excellent suggestions that I will be following up on and implementing, but if you look at the logs, it is just chugging along smoothly, then it instantly drops many of its satellites, so its position appears to change. These interferences could affect things, but they are pretty constant, so I'm not sure it would suddenly see a lot of interference all at once. I will know more as I go through these steps, though. Thanks for the excellent suggestions.

Just a follow-up on this. Finally got to properly test my camera/cable screening solution (copper tape) and the difference is night and day! Before I was rarely getting a lock after many minutes and even if I did it was 4 sats high HDOP. Afterwards I was getting a lock in < 30s with 10 sats and HDOP 0.8 on an LEA-6H. YMMV as my camera is VERY close to the GPS unit (0.5 cm) but FYI.

I'm not sure of the HDOP, that is prob in the log, but I usually have 10-13 sats within 10 seconds. Andy, I'm glad yours improved. I will try that and have results soon, too. Thanks for your suggestions.

I'm installed the Lidar Lite v2 on my cuad following instructions, I check in mission planner and sonarrange value is working but when flying, I hope, the copter still use the baro readings, I try to change some params but not luck and couldn't find the issue, or any mistake with params I did, or something with connections, the second log, a windy day, appears an ERR 0-249 , I couldn't find what means in instructions. In third log sonar alt appears but didn't work too. Someone can help me?


This from 52 log, looks horrible

re throttle stick mid position,  sprung vs un-sprung?

I wonder what the general consensus is for what people now use and prefer for the throttle stick and whether to have it spring loaded so that it sits in the middle (hover position) compared to having it un-sprung as we used in the past. 

I can see the advantage for the sprung version that it helps to keep a good stable hover at altitude where you can see it clearly.

I already have this of course on my DJIs. So I want to try it out on my Pixhawk and APM2 rigs, but would be interested first in people option, experiences and of the pros and cons of this?

Just updated to 3.3.3 and get "Prearm: inconsistent compasses"  when plugged into my desktop.  Doesn't show up in the few flights I put on, but keeps popping up while reviewing log files.  Is there something to worry about?  The graph is from it's last flight and the prearm clip is currently what's showing up on the desktop currently.

If it's only happening on the desk then it's most likely just some metal around that's causing interference.  Not sure what version you were on before the upgrade but we haven't changed much regarding the compass in any of the Copter-3.3.x releases.

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