Copter-3.6.0-rc1 available for beta testing

Copter-3.6 is now available for beta testing! The firmware is available through the Mission Planner’s beta firmwares link. Other GCSs may also make it available or you can directly download the binary from and then upload using the ground stations’s “custom firmware” link.

Changes from 3.5.5 are in the Release Notes and also copied below:

  1. ChibiOS support including F4BY, OpenPilot Revo Mini, TauLabs Sparky2 boards. Note: default for Pixhawk family of boards is still NuttX. Upload instructions are here.
  2. Flight mode changes:
    a) New Loiter with faster roll and pitch response, braking
    b) SmartRTL (returns home using outgoing path)
    c) Follow mode (allows following without relying on ground station commands)
    d) FlowHold (position hold with optical flow without lidar)
  3. Battery failsafe allows two stages of actions and monitoring of multiple batteries
  4. New sensors/drivers:
    a) Marvelmind for Non-GPS navigation
    b) RPLidarA2/A3 for object avoidance
    c) Winch for lowering packages without landing
    d) Septentrio GPS driver robustness improved
  5. New frames:
    a) dodeca-hexa copter (12 motors on 6 arms)
    b) Variable pitch quadcopter support (aka HeliQuad)
    c) multicopters with vertical boosting motor (see MOT_BOOST_SCALE parameter)
  6. Miscellaneous changes and enhancements:
    a) Auxiliary switch to enable/disable RC overrides from ground station joystick
    b) Barometer temperature calibration learning (see TCAL_ENABLED parameter)
    c) Camera triggering by distance only in Auto mode if CAM_AUTO_ONLY set to 1
    d) Compass noise rejection using COMPASS_FLTR_RNG parameter
    e) Compass interference compensation for up to 4 motors (see COMPASS_PMOT parameters)
    f) Command Line Interface (aka CLI) removed to reduce firmware size
    g) Flight mode channel can be changed using FLTMODE_CH parameter
    h) IMU notch filter to ignore specific frequencies (use INS_NOTCH_ENABLE parameter)
    i) LAND_ALT_LOW parameter allows setting altitude at which vehicle slows to LAND_SPEED in Land and RTL modes
    j) Mission cleared automatically on each reboot if MIS_OPTIONS parameter set to 1
    k) Object avoidance configurable to “stick” to barriers (previously would always slide past)
    l) PILOT_SPEED_UP, PILOT_SPEED_DN allow different max climb and descent rates in AltHold, Loiter, PosHold
    m) Safety switch configurable (i.e. only allow arming but not disarming via switch)
    n) Servo output rate configurable (see SERVO_RATE parameter)
    o) Vehicle rotation rate limits (see ATC_RATE_P/R/Y_MAX parameters)
    p) SI units in parameters, mavlink messages and dataflash logs
  7. TradHeli improvements:
    a) H3-135/140 swashplate support
    b) Reversed collective option for leading/trailing edge control
    c) AltHold angle limiter fix
    d) Five point spline-smoothed throttle curve
  8. parameter and log message name changes:
    a) ACCEL_Z_ renamed to PSC_ACCZ_
    b) ACC_ parameters renamed to PSC_ACC
    c) POS_ parameters renamed to PSC_POS
    d) VEL_ parameters renamed to PSC_VEL
    e) FS_BATT_ renamed to BATT_FS_
    h) RC_FEEL_RP replaced with ATC_INPUT_TC (functionality is same, scaling is different)
    i) WPNAV_LOIT_ params renamed to LOIT_
    j) NTUN dataflash message renamed to PSC

Although many developers (including me) have been flying this software for months this is the first release candidate so there are likely to be some problems so please be careful and report any issues by creating a new topic in this Copter-3.6 category.

If upgrading from 3.5.5 there should not be any need to re-do calibration and as much as possible parameters should be automatically copied over from the earlier release.

For those who wish to try ChibiOS, upload instructions are here.


How stable/safe is the ChibiOS port? Has it been reasonably well tested? Is it safe-ish (with the usual caveats for new technology) for general beta testing?

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Flew 8 flights today on my 450 quad with Mro Pixracer R-14 with the beta 3.6.0 rc-1.
All went Great!

Played with smart RTL for first time and a few questions:

I found I did not have Roll and pitch control until maybe the last 1 to 5 feet of touchdown.
Tried a vertical take off to 20 feet as well as a few take-offs with a sloping gain in altitude, with no difference. Upon return, I never had Yaw, Pitch, or Roll until almost touchdown. Is this normal expected behavior?

I also did a few flights where I flew BELOW takeoff height, and it also did great! ( I have a gully in the back). I was amazed on how well it did, no problems, except the issue of no R,P,Y, until almost on the ground. If this is normal behavior, perhaps a mention of this in the WIKI would be a good thing.

If I aborted at Smart-RTL then triggered again in the last few feet, I did have expected control on R,P,Y. Smart-RTL does not seem to stop and hover at the last segment as does a normal RTL command.

I was wondering what would happen if, in the middle of a Smart-RTL I hit a Battery Failsafe? I tried to time a flight so that would happen, but was unable to do so. Would it just abort the Smart-RTL and follow a normal RTL? ( Climb to set altitude and return - bee line, to home.)

EDIT : [ Found out the answer to above question today. I did a flight until about 3min battery left, then activated Smart-RTL. Halfway through Smart-RTL retracing my flight path, I reached the Battery FS. Copter stopped the Smart-RTL, and went into “Normal” RTL mode and returned to Home in a `straight line. Neat! ]

Stab, Alt-Hold, Loiter, Pos-Hold, circle, mission with RTL, and RTL on CH7 all worked perfectly!
I like the new Loiter. I did not change any settings form 3.5 as yet, except to the change to Smart-RTL.

I would like to try the new dual battery FS options, but no idea on how to do so.

Also I would like to repeat the flight using the new 1.ChibiOS , but haven’t figured out how to do that- if that is even ready-Yet.

Great Job to all.


thank you team for your hard work and giving me more fun,cant wait for next trying Chibios after ive got present one tried and sorted,ye he im so so happy

Pixracer with Chibios 3.6.0-rc1 on a small quad without any problems (stabilize, althold, poshold,guided) . Only noticed, that the logfiles are written without date on the sd-card .

Thanks to all developers.
Regards Rolf


Hello, first a big THANKS for the dev-team. Just tested a short flight with Pixhawk-Mini, frame quad+600, kiss-esc. With 3.5 I used oneshot 125 on main-out 1,2,3,4 and Gimbal, Cam on main-out 5,6,7.
With 3.6 this config doesn’t work because the Pixhawk-Mini has at all main out oneshot-125 signal.
Will D-shot be possible in the future for Pixhawk-Mini?
The new loiter feels good for the first short test.


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How you successfully loaded the copter 3.6 in Pixhawk Mini?, I have tried it several times and my Pixahwk Mini does not start.

Hello, just used latest MP. You should disconect any external devices. For example when I have the telemetry conected Pixhawk Mini doesn’t start with just USB power even if I have all external devices powered separate.

Hi Cipta,
I did it as you recommended and it is already working.
Thank you so much.

thanks for all the people involved in this project! one question, does this beta solves the well known Fly Away issue?

@JoeBreznai Wether or not SmartRTL gets interrupted on battery failsafe is a decision to make. You now have more options for battery failsafes: You can choose to use SmartRTL for a battery failsafe (and possibly use Land as a critical battery failsafe incase SmartRTL had not made it home fast enough.

Battery failsafes also have a priority system. At the moment this is the priority order for copter: (lower number is a higher priority)

  1. Terminate
  2. Land
  3. RTL
  4. SmartRTL_Land
  5. SmartRTL

What this means is if you hit a battery failsafe on your first pack that said to Land, and then hit a failsafe on the second battery instance that said to SmartRTL the copter would continue the landing action as this is a higher priority action.

Regarding the dual battery failsafes just set the BATT_FS_CRT_ACT to indicate what action should happen on critical battery, BATT_CRT_VOLT and BATT_CRT_MAH dictate when the critical battery failsafe activates.

@WickedShell; Thanks for that Information. I took a quick look at the Wiki this weekend, but failed to check out that Parameters page. Really nice options to have, especially for missions.

Loving this release so far and hope to test more. 14 flights this weekend and no issues. I tried like crazy to confuse the SmartRTL, but it worked perfectly every time! Unfortunately our weather her has shifted to high winds ( 25-34 mph) so it will be a few more days before I get out!.

Hope to try the ChibiOS next on same machine.
If I do, will I need to set up machine from scratch or will it be treated as an “upgrade” as far as parameters, calibrations etc.?

Great work and thanks to all involved.

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Parameters should not be adjusted when swapping between versions, but I’d make a back up before doing the swap and compare just to be sure.

Great stuff from you all, will try this later in the week, many thanks.

With Pixhawk 1 (2.4.5) I have the same problem… landing gears in AUX doesn’t work

test 3.6rc1 pixhack out to aux1 for gimbal tilt no longer works

Hello I looking for information on SmartRTL can’t seem to find anything except the video. Can someone link me the information to read up on this flight mode?


Great job on 3.6… I see DShot (no ESC calibration!) and ESC telemetry as great features to help understanding how ESCs are performing under load.

I would like to test them, but you’ve mentioned they are only available in ChibiOS. Are the links you’ve provided, such as, pointing to the ChibiOS firmware to PixHawk 1?

One more question: what is the envisioned approach for DShot for octo drones? I understand on PixHawk 1 and Cube 3.6 firmware is relying on aux channels, which are limited to 6.

Thank you… Luis

The ChibiOS ports haven’t been flight tested much. I’ve actually only flown it once :-). My feeling is that it’s quite solid but it’s probably not a good idea to put it on a vehicle that you would be horribly upset to have crash.

P.S. sorry for the delay in replying.


Thanks for the detailed feedback on SmartRTL. It is “expected behaviour” that the pilot gets no control of roll, pitch or yaw until the last few meters. “Expected” but perhaps not great behaviour so I’ve added an issue to always give the pilot yaw control and another to allow the control to return earlier. The yaw one at least should be easy to do before Copter-3.6 goes out. I’ll update the wiki as well.

Re the failsafe behaviour, you’ve already figured it out but in any case, the battery failsafe actions include both SmartRTL and regular RTL. So it really depends upon how that parameter is set. BTW, I need to update the docs for the parameter changes for the battery failsafes as well because they can now apply to multiple batteries but sadly the param names had to change…