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 –



    Hi, for those who followed this thread it was discussed multiple times about vehicle been unstable if we have 2 GPS onboard.

    I followed Randy`s suggestion (sorry if it was somebody else`s, but it is not an important part :) ) and I adjusted parameter for both GPS units to use only GPS system satellites, namely GPS_GNSS_MODE parameter was altered from 0 into 1.

    It has resulted with significantly shorter list of visible satellites, I have 2 M8N units on board, so it has dropped from 19-21 sats down to 11-12 on second GPS and 13-16 on bigger GPS unit and HDOP is stabilized around 0.85. It picks them up same quick as before, that did not change.

    Early morning field test had both GPS units on 11 sats with no position jumping at all, test on front lawn shows 9 sats firm on smaller GPS and mostly 15 on bigger one getting sometimes to 16 or dropping to 14. Still, a stability of pos hold was close to perfect compared to what it was before.

    So for now it is how I will keep it. Test on my front lawn also proved it to be working way better - this non-stop wandering around has stopped, vehicle seems to sit in one place in pos hold like it is supposed to be.


    • Developer

      The parameter description issue is a problem with MP so I've raised an issue for MichaelO here.

      Until that's fixed, the correct GPS_GNSS_MODE parameter descriptions are here.  The @Values show numbers that can be put directly added and put into the parameter.  If you're ok at bit math then the @Bitmask description shows the meaning of each bit in the number.  Eventually MP will be fixed and we can all just use checkboxes again.

      So I recommended "3" because this enables the "GPS" satellites (i.e. the US Govt satellites) and "SBAS".  All other systems like the EU Galileo, the Russian GLONASS, etc are disabled.  This is why there are fewer satellites seen but my understanding is that the GPS constellation is the most reliable and sometimes using glonass can actually reduce the accuracy of the solution.

      Enabling "SBAS" can also be bad though depending upon where you are in the world.  in the US and Japan it's definitely better to have it, in Australia though it can make it worse.

      Hope this helps.

    • 3702592818?profile=originalPaul, don´t know which Multi GNSS you´re using  and how did you mount them. I can´t prove this with CSG M8N and DroTek XL. (both units with 35mm patches) They are not jumping around and are serving constantly low HDOP. So turning off GLONASS might help your setup, and could depend on your location.

      I´m flying pretty often @ my shaded backyard as well ,-)

      • Hi Guys and Gals,

        I regullarly use this little bit of software from Trimble to get a rough GUIDE to what I can expect from my GPS

        It is a guide but it will help to get a gauge on what DOP values and which sat constellations are in sight ata particular time and place.

    • Thanks!  I am going to try this w/ my single m8n GPS..  On Friday I posted an image of the drift when sitting stationary in my back yard, and it was moving around randomly and had drifted about 10 meters in a minute...

    • My reading of the param is that you are now using SBAS, which is by definition more accurate. So I would surmise that your observations are expected. I guess the question is why you wouldn't want this as the default, presumably it's beacuse the SBAS signal may not be available everywhere?

      • >My reading of the param is that you are now using SBAS

        where do you see it from? GPS_SBAS_MODE is set to 2 and it was always like that, it is a default value.

        I think I tried to swap it into 'enforced' value before but it did not do much visible difference. I think those GPS units I have are configured to use it by default. I will test it later.

        • I was just going on this:


          • Old MP on laptop shows different meaning of those options. Gnss_mode =1 enforces GPS only. Sbas_mode can be set to 0 - for me it works best this way.
            Changing gnss_mode to 2 enforces sbas and i get no sats on eastern usa coast this way.
            Wiki has different values listed.
          • Ok, it makes no sense. First of all - I just updated MP software to latest beta build and now it lost all comments it used to have to describe a lot of different parameters. Descriptions for most GPS parameters are also gone now.

            Secondary, in OLD comments values descriptions were different from what is in that WIKI page now.

            What is right and what is wrong is now quite difficult to establish. OK, I guess, it is not what is important, as long as it works well.

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…
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…
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…
DIY Robocars via Twitter
Sep 24
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…
Sep 24
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…
Sep 24
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…
Sep 23
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…
Sep 22
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