ArduCopter 3.0.1 has been released and is now available in the Mission Planner,, GitHub and the new Downloads Area.

Warning #1: Compass calibration and reducing interference is far more important than with 2.9.1b

Warning #2: GPS glitches can cause sudden and aggressive position changes while in loiter mode.  You may wish to reduce the Loiter PID P to 0.5 (from 1.0) to reduce aggressiveness (see image below of where this gain can be found in mission planner).

Warning #3: optical flow is not supported but will be back in the next release (AC-3.0.2 or AC-3.1.0).

Warning #4: loiter turns does not maintain altitude.  This bug will be fixed in AC-3.0.2.

Warning #5: This release has only been lightly tested on Traditional Helicopters.

Improvements over 2.9.1b include:

  • Inertial Navigation for Loiter and Auto meaning much more accurate control (Randy,Leonard,JonathanC)
  • 3D navigation controller follows straight lines in all dimensions between waypoints (Leonard,Randy)

         WPNAV_SPEED, WPNAV_SPEED_UP, WPNAV_SPEED_DN, WPNAV_ACCEL allows configuring speeds and acceleration during missions

  • "compassmot" to compensate for interference on compass from the pdb, motors, ESCs and battery.  (Randy,JonathanC) (Set-up video here)
  • Safety improvements:
    • simple Tin Can shaped Geo Fence
    • pre-arm checks to ensure all calibration has been performed before arming (can be disabled by setting ARMING_CHECK to zero).  (video description here)
    • GPS failsafe - switches to LAND if GPS is lost for 5 seconds
    • stability patch improvements to stop rapid climbs in very overpowered or overtuned copters
  • Circle mode improvements including "panorama" when CIRCLE_RADIUS set to zero (Randy,Leonard)
  • SONAR_GAIN parameter added to allow better tuning of sonar surface tracking
  • CH8 auxiliary switch (same features as CH7)
  • works on PX4 (some minor features still not available) (Tridge,PatH)

How to upgrade:

1. Make sure you are using Mission Planner 1.2.59 or newer (get it here)

2. Click on the MissionPlanner's Hardware, Install Firmware screen.  The version numbers should appear as "ArduCopter-3.0.1", then click the appropriate frame icon and it should upgrade as per usual.

3. Reduce the Loiter and Alt Hold PIDs if you have modified them from the defaults.  The modified PID values for the 3DR frame can be seen in the image below.

Note: Nav parameters have been combined with Loiter so do not be concerned if you can't find them.

4. Although not directly related to this release, if you purchased an APM prior to March of 2013, update your PPM encoder to the latest firmware (instructions here).

5. Try out the new version in stabilize mode first, then alt-hold, then loiter and finally RTL and Auto.

Numerous How-To videos are available:

Special Thanks to MarcoDaveC and the large number of testers on the pre-release thread who put their copters at risk during the extended testing period.  Some of their videos can be found hereherehereherehere and here.  Thanks also to MichaelO for the MP changes required for this release.

All feedback welcome.  Please put your questions, comments (good and bad!) below.

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Did you do this bit?

#define OPTFLOW DISABLED // disable optical flow sensor to save 5K of flash space
#define MOUNT DISABLED // disable the camera gimbal to save 8K of flash space

if you did, try also disabling the auto tune.

Another bonus for manufacturers like 3DR

Detlef, Bruce,

     Thanks very much for testing this.  Drag that the slower speeds aren't working for Bruce (and most aren't even working for Detlef).  I was wondering if you could try this one as well.  I don't think it will work but there's a chance it might.  It's running at 8mhz but there's a small delay added between when the "chip select" pin is pulled (low i think) and when it starts to send or receive data.  Basically the theory is not that the rate is too high but that it takes a small amount of time for the chip select pin being pulled low to reach the mpu6k.

     This version is not exactly AC3.1-rc5.  It's actually 'master' so it's got a few other changes in there that haven't been tested all that much so I wouldn't recommend flying it (although i have this morning).

I compiled with Arduino firmware and loaded on APM2,
I also disabled
# define AUTOTUNE DISABLED / / disable the auto tune functionality to save 7k of flash

 All OK!!

The memory of APM2, is almost full.....  ;)

To SAVE Flash memory space for hex file size:

Append this at the end of APM.Config file:


--- Result ---

Compiling 'ArduCopter' for 'Arduino Mega 2560 HAL (Apm 2)'
Binary sketch size: 245240 bytes (95% of a 258048 byte maximum) (56.53 secs)

Note: You can remove more things from the code to fly it with minimum features, I just got my final memory size down to 175,000 bytes. Almost 70% of final size and copter still flies the same :)

OK so any number is valid and just represents the minimum throttle. I must have went to low and the motors refused to start. Set to 100 it's working fine.

Hello Randy,

Here comes the 8MHz delay log. No change in twitching.

Besides, like the logs before I only powered the APM board and external compass over the USB port. RX and ESCs are connected but not powered up in order to eliminate interference by any noise they create.

Thanks for all you efforts!!



When the winds calm down I will post again with video and logs. It's an Octo with:
4 of these:
APC 12 x 4.5
6 kilo in total with camera and gimbal but I'm tuning without that. Adding weight should calm it down naturally which is what I would want when carrying the camera.

Where can we get a full list of all the features that can be disabled and those that should be left enabled?

Randy I really appreciate your time!  Here are is the log.  As you'll see, the HUD dance continues.  Is it possible there is a HW issue?  Are there many of us experiencing this with the RC4+ FW?



Ciao  leonardthall,
I was able to try the modified firmware as per your instructions, the test was great, the behavior was perfect, no oscillations or twitching, the flight was smooth and continuous. I think the change that you want to include in the code is OK for me with my frame has given excellent results.
you place the log and a small video.

Thank you for your patience and explanations.



Bruce, woow - I just played your log in MP, that is allot worse than mine. Your HUD is all over the place.

Besides my twitchy APM its only you who I personally found on the net who complains about it. The question is how many fiddle around with BETA versions? I would say this behavior is fairly rare but I would guess that we find a few more joining us once this version is released as normal version.

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