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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"ESC hickup"

So You're saying this could happen randomly to anyone, anytime?

Never heard that kind of hiccup especially caused by ESC.

Never heard of it either.

In the log I can also see that there is a huge spike at the end on motor #1.

But..............what is the cause if this spike?

I don't want this to happen at 50 meters high!

I see what Michael says which is a current spike even though the output to the motors is zero.  To be clear, that ESC hickup would need to be an issue within the ESC itself or possibly a very low level hardware (i.e. a power spike is somehow getting into the Pixhawk) or software problem on the Pixhawk.  Ardupilot is requesting zero outputs be sent to all the motors so it's not a high level software problem.

Thanks Randy for investigating my problem,

It's a bit hard for me to understand your explanation(s), because I'm not a programmer .(just a fanatic diy man)
As far as I can follow you:
Is it most likely the esc itself that's causing the spike?
Do you have any advice in this matter?
BTW: the esc's I'm using are "Spider 30A OPTO 2-6 lipo 600Hz"

Paul, yes, I think it's the ESC or some other power related issue on the vehicle.  There are many things that could cause a spike on the pwm signal pin .. for example, are the ground wires from the ESC connected to the pixhawk's top rail (on the back of the pixhawk)?  The issue is very unlikely to be in the ArduPilot software.

"for example, are the ground wires from the ESC connected to the pixhawk's top rail"

Randy, I have all the esc GND wires at the top of the Pixhawk and the signal wires at the bottom.

I sense that you have more options for this problem.

Can you please suggest some more possibilities?

It could be one of so many things.. It could be an FPV radio or other radio that has been placed close to the ESC signal wires.  I've definitely seen cases where a servo gets upset and begins shaking when it placed near a 3DR radio.  The power of an FPV radio system is much higher.  I haven't heard of this affecting ESCs before but it's possible.

From looking at the logs the main flight controller's voltage drops by 0.3V at the same time as the current spikes.  It happens earlier in the log as well.  That's a bit odd, could there be a high powered radio (like an RFD900) or some other sensor (Lidar perhaps) that's pulling power directly from the pixhawk?  If "yes" then powering that device from a BEC might help.

Wow Randy, I'm learning a lot here......

Never to old (67) to learn, lol.

The Pixhawk is powered by a seperate bec (not by esc)

The Pixhawk is supplying power to only the FrSky RX and a 433 mHz module (for using Tower app).

The 433MHz 100mW module is rather close to the "failing" esc and the antenna is only 3 cm from the esc. So I will unplug it for the time being.

So no such thing as RFD900 and/or Lidar.

1 GPS, external compass and external led are also powered by the Pixhawk.

I have also an extra VCC and GND wire from the bec to AUX 4 of the Pixhawk. So not only a power line to "the "power"plug on the Pixhawk, but also power wires to the AUX 4.

Could this give problems?

AND also a powerline (vcc, gnd) to AUX 5 on the Pixhawk for powering my landing gear. It's only working temporarily for retracting and deploying, but could this be an issue?

I'm using copter v3.3.3 on a tricopter as shown in the diagram below. My yaw servo is plugged into a Pixhawk main out 7.

I don't seem to have any control of the yaw servo when the safety switch is armed or when the tricopter is armed. Should I expect the transmitter yaw stick to control this servo on the tail motor? Are there any settings I may have missed to select a tricopter other than when downloading the firmware?

Thank you...


you can´t control the servo with the yaw stick, it is controlled by the FC when flying.

as Hubertus mentioned only FC controls that servos, try raising throttle to about 20% aand you'll be able to. 

also, there are a few settings to set for proper yaw control on a tricopter, otherwise it will be "laggy".

ATC_SLEW_YAW = 18000 
ATC_Y_MAX = 100000 

these are for ac3.4, so to find them in ac3.3 just omit the "ATC" part.

if you encounter "wagging tail" try lowering yaw_stab and yaw PIDs. D needs to be 0 for the "manual like" yaw control, otherwise AC controls yaw too much and it gets slow... 

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