Copter-3.3 beta testing

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!

You need to be a member of diydrones to add comments!

Join diydrones

Email me when people reply –


      • I've recently seen the behavior you are describing as well, but I don't believe it is related to the problem I reported here.   The issue I reported in 2266 only causes small constant errors in roll or pitch.  I did submit a pull request for 2266 last night.  If you can't find the cause of the erratic behaior, you may want to file a separate bug.

  • Tryin 3-3-rc3 on small 600mm CF quad.

    - Could not calibrate accelerometers on the table using radio link. Was successful using USB link first go. ??

    - Compass calibration even with 2,500 + points didn't "auto accept" (using radio link)

    - Radio calibration using Taranis and "native" channel order (e.g. Throttle on channel 3 instead of normal 1) was easy through radio link.

    Using Quanum telemetry, I did disable on board failsafes related to battery..

    Flying test:

    Take off was smooth and easy in stabilize.

    Moving on to ALT Hold was very good.

    As soon as I changed to loiter, the quad decided to go where he felt better and crashed. 

    Perhaps someone could tell me more about it looking at the attached bin file?

    Thank you in advance.


    • Bin file didn't upload..

      2015-05-09 15-30-50.bin

      • Hi Henri,

        What GPS module do you use?

        I hope that the developers look into this, I had exactly the same issue with 3.2.1

        • Using M8N

          Not sure:

          - Mission Planner and 3.3-RC3 (11th May 2015)

          - Shielded audio cable in between the Pixhawk and the M8N (no more noise on SDA line)

          compass calibration was really easy. and both internal and external were showing on the nice "calibration balls"

          Accelerometers calibration went fine with radio link. (no need to use USB to do so now)

          After powering it off and back on, after calibration,  the altitude was correct!

          So it does looks promissing..


        • Good morning Geert.

          Using this one: M8N. But after the crash, I decided to investigate the compass side. So I connected an oscilloscope onto the SCL and SDA lines (directly on the little tower 15 centimeters above the Pixhawk) to see if anything was not correct. Well even the I2C clock line looks ok the I2C data line (SDA) is very noisy and small spikes are very visible on the scope. 

          Now running each SDA and SCL line on shielded audio cable to improve the noise margin. I am surprised as normally 400 pF is possible by the I2C standard. Don't know where this "coupled noise" is coming from.


          • Hi Henri,

            Two qeustions:

            1. Could you use a ferrite ring to lower the noise spikes of I2C signal?

            2. Did you use somekind of stereo shielded cable?


            • Developer

              Please reference section 7.5 of

              7.5 Wiring pattern of the bus lines In general, the wiring must be chosen so that crosstalk and interference to/from the bus lines is minimized. The bus lines are most susceptible to crosstalk and interference at the HIGH level because of the relatively high impedance of the pull-up devices. If the length of the bus lines on a PCB or ribbon cable exceeds 10 cm and includes the VDD and VSS lines, the wiring pattern should be:

              SDA _______________________

              VDD ________________________

              VSS ________________________

              SCL _______________________

              If only the VSS line is included, the wiring pattern should be:

              SDA _______________________

              VSS ________________________

              SCL _______________________

              These wiring patterns also result in identical capacitive loads for the SDA and SCL lines. If a PCB with a VSS and/or VDD layer is used, the VSS and VDD lines can be omitted. If the bus lines are twisted-pairs, each bus line must be twisted with a VSS return. Alternatively, the SCL line can be twisted with a VSS return, and the SDA line twisted with a VDD return. In the latter case, capacitors must be used to decouple the VDD line to the VSS line at both ends of the twisted pairs. If the bus lines are shielded (shield connected to VSS), interference is minimized. However, the shielded cable must have low capacitive coupling between the SDA and SCL lines to minimize crosstalk.

            • Hi Geert.

              Ferrite rings are more (or less) not  good news for the flight controller mag sensors. 

              Yes I used plain small shielded audio cable and that did improve nicely the spikes on the SDA line of the I2C bus.

              I guess a twisted  pair cable of ground + sda signal should do an equivalent task.

              No matter what it isn't a good idea to have relatively fast signals traveling long distances ( 10 centimeters or more ) without a ground data signal in between them. 


      • Found a weird issue with the latest beta version of MP build 1.1.5599.32514 and firmware 3.3rc3.

        When I loaded up the firmware it was taking forever for the parameters to download.  I waited 30 minutes or more but they never completed.  I could cancel out but then some of my parameters wouldn't come across so I was prompted to do all of my calibrations all over again.  I wasn't able to select frame type either.

        I rolled the firmware back to 3.2.1 and everything is normal.

        Yes, I believe that this is a MP problem but thought that I'd throw it out there to see if anyone else has experienced this?


This reply was deleted.


DIY Robocars via Twitter
RT @a1k0n: Did I get rid of hand-tuned parameters? Yes. Am I still hand-tuning more parameters? Also yes. I have a few knobs to address the…
1 hour ago
DIY Robocars via Twitter
RT @a1k0n: I'm not going to spoil it, but (after charging the battery) this works way better than it has any right to. The car is now faste…
1 hour ago
DIY Robocars via Twitter
RT @a1k0n: Decided to just see what happens if I run the sim-trained neural net on the car, with some safety rails around max throttle slew…
7 hours ago
DIY Robocars via Twitter
DIY Robocars via Twitter
RT @SmallpixelCar: @a1k0n @diyrobocars I learned from this. This is my speed profile. Looks like I am too conservative on the right side of…
DIY Robocars via Twitter
RT @a1k0n: @SmallpixelCar @diyrobocars Dot color is speed; brighter is faster. Yeah, it has less room to explore in the tighter part, and t…
DIY Robocars via Twitter
RT @a1k0n: I'm gonna try to do proper offline reinforcement learning for @diyrobocars and throw away all my manual parameter tuning for the…
DIY Robocars via Twitter
RT @circuitlaunch: DIY Robocars & Brazilian BBQ - Sat 10/1. Our track combines hairpin curves with an intersection for max danger. Take tha…
DIY Robocars via Twitter
RT @SmallpixelCar: Had an great test today on @RAMS_RC_Club track. However the car starts to drift at 40mph. Some experts recommended to ch…
Sep 11
DIY Robocars via Twitter
RT @gclue_akira: 世界最速 チームtamiyaのaiカー
Sep 10
DIY Robocars via Twitter
RT @DanielChiaJH: Always a good time working on my @diyrobocars car at @circuitlaunch. Still got some work to do if I’m to beat @a1k0n howe…
Sep 10
DIY Robocars via Twitter
RT @SmallpixelCar: My new speed profile for @RAMS_RC_Club track
Sep 10
DIY Robocars via Twitter
RT @SmallpixelCar: Practiced at @RAMS_RC_Club today with my new @ARRMARC car
Aug 28
DIY Robocars via Twitter
Aug 24
DIY Robocars via Twitter
RT @gclue_akira: 柏の葉で走行させてるjetracerの中身 #instantNeRF #jetracer
Jul 4
DIY Robocars via Twitter
Cool web-based self-driving simulator. Click save when the AI does the right thing
Jul 4