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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Ah good deal Michael, glad that worked out the way you wanted.  I put mine up to 80 :)


Just loaded RC5, it does not arm, no settings changed.. I know some people have raised this issue before on this forum. As this forum is almost 200+ pages long its rather tedious to find.

Can someone tell me how do I arm it now, red light keeps blinking (btw, this is my 100+ flight) :-P, so something must have changed in code :)



Jim.. when you say "the regular 3.1 release" do you mean 3.0.1?  -rc5 is for 3.1 which isn't released beyond that release candidate yet, that's why I ask.

I've rolled back the changes and compiled successfully(RC5).  I'm curious if any other libraries/functions are affected by reverting back to the original bus speed.

I plan on testing it today when I get off work. Doubt I'll fly with it.  Just want to test if it solves my problem.


Ah, that was it.

Had to move the quad some few meters away to get it do the RTL.

Thanks Jim. Problem is solved :)

Good point Detlef.  Especially if it's a tolerance issue. Though all boards meet a tolerance on initial production speed requirements, a few may be on the edge or just outside the boundary of the hard coded High Speed setting.

I did some more aggressive testing of 3.1rc5.

After autotuning (it flew great) I decided to start playing with flips. I read across Rob's post where IIRC he liked an ACRO_RP_P of 6.5, so I decided to try 7 (hehe, from 4.5). That was interesting; you get fast flips but IMHO it becomes difficult to finesse through gaps. I normally don't run expo on my tx. So I tried dialing it all the way up to 50% and I was still over correcting all the time. So I think I'm going to fall back to 4.5 to get used to shooting gaps with the rig, then I'll carefully dial up the flip rate & expo to get a better balance of precision and quickness.

I also got to play with Loiter, Acro, Alt, Stab, and RTL on an exceptionally windy day (25mph, with 38mph gusts). Loiter was excellent; watch the part where I loiter in front of myself. It tilted about aggressively in the swirling winds behind those trees, yet maintained a solid position. I think if I softened it up it would not look or sound so scary, but then it would probably drift in heavy winds. Early in the video I played with aggressive yaw in loiter, and as you can see the position was rock solid, and no toilet bowling even with my built in compass.

The RTL... my control rx just so happened to failsafe in that wind. I haven't tested RTL since the recent processing speed improvements. So I decided to let it do it's thing. It flew faster toward home than I'm used to probably due to the tail wind. I'm set for 30mph lateral max, but the trip home was short so it started slowing just after it broke 20mph. The ascent and descent performance with the latest code is phenominal! The descent was now so fast it scared the c**p out of me; it took a lot of faith for me to not take over control at that point. Fortunately it stopped on a dime right in front of me, but it may take some time for me to get used to the "daring auto descent" LOL. My 'max auto z' settings are +350 and -250, which my rig seems to be able to handle well; so I'm keeping it that way. I also like the newer feature where RTL yaws to launch heading before descent; I suck at transitioning from the monitor to LOS. ;)

Once again... cheers to the devs! :)

Bruce, Detlef.

Thanks for testing this. It's an important problem and we must find the real cause of it.

I do not think that this is a board tolerance issue, because we are far from the limit at 8 Mhz (the specified limit is 20 Mhz) and the SPI signal quality / timings on my board was very good. So good that i don't think that some boards could be bad enough to cause problems.

I would be interested to know how you are powering the APM board, and ask you if possible to redo the 8 Mhz test with a 5V BEC connected on a PWM input connector.



No problem.  I'll hook up a BEC to it this evening and report back!  

Thanks Olivier,


Hello Oliver,

Usually I feed the APM over the PWM outputs with a "Turnigy 3A UBEC w/ Noise Reduction". JP1 is closed (over a switch) and I jumpered the onboard fuse F2 and diode D1 so Vcc & 5V have all the same levels. The UBEC makes ~5.1V while my USB port is pretty much exact at 5V.

I have the problems either way if powered with USB or with UBEC. If I use USB (JP1 open) nothing else gets power in my setup - that's how I did the logs for Randy. I even disconnected the GPS while testing. I assume that external interference can be excluded in such case. I have a second board powered over USB (no peripherals connected) that doesn't show those issues so I assume my USB port is good to power the board without causing any problems. Could the wiring of the external compass cause some issues? I haven't tried to disconnect it.

Here are some pictures of my quad: - GPS and compass sit on the top level.



I'm flying Acro with RP 10 now. :)

I didn't find it hard to control, I was actually pleasantly surprised.  Though, I don't know if I could do precision flying with it.  Could try a D/R switch too.  I have one set up, but didn't use it yet.

Hello. Today i test 3.1-rc5 on my quad X. 450 Size, 1000kv motors.

Autotune very good. More stability on fast land and more stability with sticks drop.

I have some questions:

1) What indicates YELLOW led in APM 2.5 (near blue GPS and red)?

2) I try Acro and i do not recognize the new behavior... Very strange and not habitually. If i fly only roll or pitch - then all ok, but i fly roll and pitch - then autorotation and fast fall. If i release sticks - then copter not stay horizon and fly down and side. I not see this behavior in 3.0.1. Please give instructions how i may do behavior how in 3.0.1

3) Battery "FailSafe" text always show in Flight data screen. I off checkbox in failsafe and alarm but i see this message again.When i off battery sensor (simple 2 resistors) in Additional hardware - then message off in Flight data. It bug or feature?

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