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!

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  • Hi,
    I made a few posts about GPS drift and other seemingly GPS related issues. 
    I was using an inexpensive RTFQuads m8n.  I got one of the CSGShop ones, and it is actually much better!  I was skeptical, but it definitely drifts less now.   It's also clearly using higher quality components.  Its battery stays charged.  It gets satellites in seconds rather than minutes.. 

    I'm concerned that while I was having GPS issues, copter tried to fly away a couple times.. Copter would not switch in to Loiter mode, etc.  There was nothing in the logs, that I could find, to indicate any issue. (always had over 10 sat's, under 1 HDOP)  But, the GPS was certainly causing some problems.

    • What is a bit problematic about all this - I get sometimes fine results from any GPS units and sometimes there are obviously some issues, but there is no obvious way to raise any alert or quantify level or GPS correctness that results in the unexpected behavior. RTFQ or CSG or complete no-name unit should not matter that much as long as GPS returns a proper result set, but obviously something else is going on that affects all this.  

      But it is quite obvious now that CSG units seem to be much less problematic than anything else and even if they cost twice more than their competitors, it is probably still a best choice. It is just too bad we cannot figure out how to measure this specific parameter, what makes one unit to work fine and other to produce garbage readings.

      • I'll be happy to share logs, if anyone is interested. 
        I will gladly plug in both GPS units to either the same pixhawk, or two different ones, and log them sitting next to each other. 

        I've done several tests now, and there is definitely a big difference in performance. 

        The CSG one was 3x the cost, and I'd say from the past two days results, it is 3x better!

        • I have no issue paying more for a significantly more effective implementation. It's true all of these have M8N but different antennas, trace/PCB quality, and antennas certainly will make a difference. My question is: what CSG board are you using? Is there one that is either in a case like the 3DR/rctimer/etc. or have you found a case that works? All that I have seen are bare boards. DIY is fine for one-offs but I need something repeatable for research craft.

          Personally all I have ever used is the rctimer M8N and it has seemed fine for me, but I wouldn't mind an improvement if the CSG boards provide that.


          • rsiqssqg.jpg3702851095?profile=originalI´m using the CSG M8N since 2014 when the first big one with 35/4mm taoglas patch came out and they still perform great  and the DroTek XL (not the XXL) with the 35/6mm taoglas patch which is great as well and I´m using either a GLB Flight Controller Housing or 2 pcs. 45/50mm glass fiber board, which looks a lot better.




            I tried several cheapo boards with M8N, but some of them performed even worse than the good old 3DR LEA V1.1, won´t use them for expensive rigs . But for those who even use the PX Lite on a low cost setup they maybe even good enough .

            • @gervais

              It is great to see that CSG shop, and Drotek provide "Quality implementation" of the M8N GPS.

              Drotek M8N,  CSG M8N without large diskCSG M8N with EMI protectionCSG M8N other version


              Exeptional linear voltage regulator with more than 55 dB noise rejection (10Hz to 10MHz) and output noise of  4.17 microvolts rms maximum

              You can get these amazing little regulator boards here: Voltage Regulators

              The GPS will have no reason to "behave badly" due to noisy power lines :-)

              It is now up to everybody to decide if they want to "gamble" and use some "el cheapo GPS board" with "disastrous noise" on the GPS's power lines. 

              There is a good switching noise blocker from Micrel:


              Another way to stop the switching noises from your "switching voltage regulator".


          • @crayfellow

            I have never used the rctimer GPS.

            However I have used three different implementations from CSG M8N.

            One thing worth mentioning is that I always power the CSG units, and the others, with a noise free 5 volts power.

            (Certainly not a switching line carrying added noise from ESCs) :-)

            I took care of insulating the GPS from radiated EMI noise as well.

            The best I got of the three is CSG M8N and compass The second best I think would be this one: CSG M8N medium with compass

            I used other GPS such as LEA6H, neo7 and many more. For whatever reason(s) the ones I mentionned above (see links) are doing a fantastic job for me. 



          • I have 5 different "budget" m8n's and they all perform fine for me. True I always fly in the open, I never take off until I get max sats [usually from 18 to 20] and the lowest HDOP. The RTFQ mini works GREAT on my 250, a BeStar that started out HORRIBLE now works the best out of all of mine on my beater 300 woody and 2 that are in pucks work great on my 800 hex [it's the ONLY thing working great on that bird right now :(] and one on my 800 X8. If I could afford one of the CSG boards I would get one to test against my other units but I have so many other things I want/need to buy that it is really low on my list :)

            • Are there any specific settings you like to tweak on the M8N in U-Center? I installed a Neo-M8N today (ebay, combo gps / mag puck) and it does a good job picking up sats quickly, but MP keeps screaming "bad AHRS" at me constantly. Even with an HDOP of .89 and 13 sats, 3D Fix.  I've tried a number of things in U-Center (turning off SBAS, etc) but to no avail.   My CN06 that was on previously did not have the 'bad AHRS' message even with a higher HDOP and less sats.  I have AC 3.3 RC11 on board. 

              I've googled around and seems a lot of folks have had this issue to some degree as far back as 2011, but no clear or concrete solutions / reasons.

              • Developer

                The bad AHRS shouldn't come from the GPS but it can be caused by the EKF being unhappy with the compass, accels or gyro values.  Maybe have a peek at the live EKF viewer in mission planner or Tower?

                For the M8 GPS Marco's recommended config can be found here.

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