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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Hi Xin, i use on my video Futaba sbus rx with the "master" version (latest commit by Randy), aka 3.11 when released.
If you want, but at your risk, you can flash this hex (i fly with this one now, no problem) to your PX4 board with the Planner selecting "load custom firmware", you can download here the right version for your frame (select the "v1" version", the other one is for Pixhawk).
This is not an official release but a dev firmware, so you are warned! ;-)
Is important the "PX4IO" upgrade, is automatic but pay attention to the right buzzer signals, not the "Beethoven's Ninth" but the first three note of theme from "Close Encounters of the Third Kind", with three consecutive beep at the end if the PX4IO upgrade is succesfully completed.
If all work fine remember to recalibrate your radio with the Planner, the correct range is near "1100<->1940", have fun.

I'm sorry Walter but i don't understand your problem when yawing during Loiter, this is a task that I always do the test and I have never had problems like that, like high altitude drop or shutdown the copter.
Yawing to the right or to the left? For security i put the yaw always in the "arming" direction (to the right), like in my videos.
If you think there's bug please post your report on the "APM Forum", with logs of the issue.

Hi Macro, thanks for the link. I've flashed it with my PX4 but still no luck. All channels are zero.

But I did noticed some differences. The FMU board has no red light flashing on 3.01, after flashing 3.11 it has a flashing red light (one long flash follows one short flash). And the safe button doesn't react at all (it won't turn solid red light after pressing for 5 seconds).

I tried both heli and quad version of the hex. The tones do change like 2-3-1-1-1 with three consecutive beep (1-1-1) in the end. Seems I'm doing it right but really no idea why it doesn't work.

Force the PX4IO upgrade, read the docs here.

Xin, I think you may be suffering from the same problem I had.  You cannot update the IO Firmware with the 3DRadio plugged into UART5.  You must disconnect it, do the update, then reconnect it.

So power down, disconnect the telemetry radio, hold down the button, plug in the battery.  When the "Close Encounters" tune begins, release the button.  The tune should repeat 4 times then end with two notes.  Then the update is complete.  Unplug the battery, and replug the 3DRadio into UART5.

Yes I did it with the new method, now it works! even with the stable 3.1 version.

However, the tones doesn't sound like the wav file in the wiki, it sounds just like old 3.0.1. Is that normal?

Hi Rob, I don't have anything connected to my PX4 when updating, but you did remind me something, it's the SD card, and I've finally found out what the problem is.

When we were updating old versions like 3.0.1, the PX4IO firmware was written in the SD card as well, but somehow this old firmware screwed the 3.1 update. The same for the 3.1.1.

If I delete the APM folder in the SD card where the old PX4IO firmware is located, disconnect telemetry, do the update, then everything goes smooth, the tones are now correct as shown in the wiki, and my sbus is back. I don't even need to force PX4IO update.

The same problem happens again if I roll back to 3.0.1 and do the update without erasing the SD card, so it seems to be the cause of my problem.

So I think it's necessary to delete the APM folder of the SD card before updating, and disconnect the telemetry as well. Otherwise it may go wrong.

i thought i would revisit this thread to make sure the information i have ascertained is conveyed properly. so far the ONLY connection that isnt quite compatible between the APM 2.6 & Pixhawk is the Telemetry connection. if you PURCHASED a telemetry package from 3DR (the New One in a protective Case) you were given two cables, one for APM, the other for Pixhawk. the APM is a 5 pin to 6 Pin Connection, the Pixhawk is 6 pin to 6 pin. so it is not a COMPLETE clean swap because of this one cable/connector as stated from 3DR Phone support line. so be wary of this, you will have to order that with your Pixhawk from the 3DR store. hope that is helpful to anyone seeking this transition from APM 2.6 to Pixhawk.

3DR....*please* drop this ridiculous cable.

Please use standard 5 position cables or 6 position cables. This non-standard 6/5 thing is a bad enough, but you only provide one length! With "standard" 5 or 6 position connectors we can at least get longer cables if we need them.

I already use these units they are fantastic .. all sensors in one tiny package

Ruben,can you connect that to APM in order to read voltage and current?


     thanks for figuring this out!

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