After months of testing AC3.1 is finally available in the Mission Planner and GitHub.

Warning #1: If the vehicle is left landed (but armed) while in AltHold or Loiter mode for more than a few seconds, the vehicle may suddenly jump into the air the moment the pilot raises the throttle above zero.  The reason is the baro altitude may fall while the vehicle is sitting on the ground.  In AC3.2 this bug is fixed because we reset the target before take-off.

Warning #2: Motors will spin (slowly) by default as soon as the copter is armed!  You can switch this feature off by setting the MOT_SPIN_ARMED parameter to zero.

Warning #3: if you see "Bad Gyro" on the HUD then you may have a blown 3.3V regulator.  See this thread for details.

Warning #4: if you use a sonar set the SONAR_GAIN parameter to 0.8 or lower

Warning #5: Trad Heli users should now connect their main rotor ESC to APM's RC8 output

Warning #6: Trad Heli BUG causes loss of collective control in ACRO mode if swash type set to flybarred (i.e. not flybarless).  Will be fixed in AC3.2.


The major improvements over AC3.0.1 are (full list here):

1. Pixhawk support (Tridge & PX4 development team)

2. Autotune of Roll and Pitch gains (Leonard/Randy)

3. Drift mode (Jason)

4. Improved Acro (Rob/Leonard) and new Sport mode (Leonard)

5. Arming, Take-off, Land in Loiter or AltHold

6. TradHeli improvements (Rob) including:

a) support for direct drive tail rotors

b) smoother ramp-up of main rotor

c) reduced collective for better control in stabilize mode (STAB_COL_MIN, STAB_COL_MAX params)

7. Support for SingleCopter (Bill King)

8. Performance improvements resolve AltHold troubles for Hexa & Octacopters

9. Safety Improvements:

a) GPS Glitch detection (Randy)

b) Motors spin when armed (Jonathan Challinger)

c) crash detector shuts off motors if copter flipped for 2secs

d) batt failsafe option to RTL instead of LAND, gps failsafe option to trigger AltHold instead of Land

e) more pre-arm checks of inertial nav speed,

10. Bug fixes:

a) optical flow working again (although performance is still not great because not integrated with inertial navigation)

b) ROI working (use DO_SET_ROI command)


How to upgrade:
Click on the MissionPlanner's Initial Setup >> Install Firmware screen.  The version numbers should appear as "ArduCopter-3.1", then click the appropriate frame icon and it should upgrade as per usual.

Special thanks to Marco and the many beta testers on the AC3.0.1 thread who put their copters at risk during the testing of this new version and uncovered many problems so that you don't have to!  Here are some of their videos: loiter in wind, patio sonar, autotune, autotune2, roi, beach, acro, vrbrain, tricopter, train spotting, radio failsafe, the tree, double loiter


If you haven't seen it recently, please check out the ArduCopter wiki.


Feel free to post comments below and we're going to use the new APM Forum for support issues so please post your support requests there.

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LOL, i would have liked more try the new GPS! I don't understand such as connectors or cables have been provided for in the rectangles that you see on the sides, one thing is certain, in this prototype is missing something... ;-)

Similar discussion on Pixhawk interface detail.

The logic level of telemetry to Pixhawk, is it 5V or 3.3V?

APM2.x has 5V logic level on telemetry. The PX4 has 3.3V logic level.

The reason is that xBee is most convenient method of wireless communication in Japan.

Cool - but how much space underneath will I need? I anticipate installing this on the top plate of my quad, but only have 29mm space underneath (and I don't want to have to drill the bottom plate as well). Will it fit?


Today is obviously my day for stupid questions...because I have another.

I've recently invested in a DX18 and the 18 channel rx for my workhorse. I also went with the 2 sats on 30cm in "diversity", since my frame is all CF.

What's the best approach - a PPM encoder for the "primary 8" channels (leaving the xplus 8 for the normal peripherals, and allowing me to retain the TM1000), or can I rig the 2 sats into the SPKT/DSM port somehow, and use all the pixhawk channels?


Edit: Ignore the PPM encoder bit - I see that's been answered over on the other forum.


     All the Serial ports are 3.3V but also 5V compliant.  So I guess they'd like to receive 3.3V but they'll be totally fine with 5V.

If you have 29mm space underneath is enough.
For this i've created a small carbon strip, i never drill the frame.


Thank you for quick response. That sounds good. I will report the xBee result later.

BTW. I had some experience that unable to uploading firmware from Mission Planner(1.2.92) on Windows7 64 bit. The procedure of uploading is based on wiki page. The symptom is that Mission Planner could not detect Pixhawk. The other computer runs 32bit Windows8.1 could upload firmware without any issue.

Randy, are you using s.bus with your futaba? After upgrade to 3.1 my PX4 doesn't reconize s.bus signal anymore, If I flash 3.01 back it will work again. Is there anything I need to do to make it work?

Maybe a bug... Flying mostly development code, I've flown 3.1-rc7 with my newly build tricopter. All flies very well, but in Loiter, when trying Macro's trick to let the copter spin using Yaw, the motors sort of shut down and copter went to ground. Releasing yaw, let copter recover and continue loiter at original height. First I thought that copter could not maintain height when too much yaw applied, but also when trying with very little yaw, the same thing happened. When doing the same trick in Stabilize mode, copter behaved normal.

Maybe this was fixed in the final release. Since weather is really bad here, I didn;t try that yet.

If weather gets slightly better I'll try again and will also try the quadcopter. Maybe some other tri-copter fliers are able to test the same (Macro) trick.




     I didn't realise that SBus worked in AC3.0.1.  You're right that there's a problem with it in AC3.1 which has now been fixed in master.  We're looking at doing at least a release candidate and quite possibly an AC3.1.1 release that will include the fix.  That should happen within 2 weeks.  sorry for the troubles.


     Hmm...I'm uploading ok but I'm using Windows8 64bit.  Have you seen this wiki page?  This page includes some instructions at the bottom for reinstalling the pixhawk drivers that may help.

Thanks Randy. I'm looking forward to the update.

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