Copter-3.4 has been released!

As reported on this blog post, Copter-3.4 has been released and is available as the default firmware through all the ground stations. The previous version (AC3.3.3) can still be downloaded using the MP’s “Pick Previous Firmware” versions link and selecting “AC3.3.3”.

This version is identical to AC3.4-rc7 with the exception that the LeddarOne lidar driver has been disabled after some issues were found during testing (thanks LanceB!).

There are still some known issues with AC3.4 which we will address in AC3.4.1 which we plan to push out within a couple of weeks.

  • Pixracer’s 3rd compass often causes difficulty with the onboard compass calibration and a “Compass Inconsistent” message may appear when arming. It is probably best to disable the 3rd compass by setting COMPASS_USE3 to 0.
  • Pixracer may not bind reliably with DSM transmitter/receivers.
  • The LeddarOne driver has been disabled temporarily after some issues were found in testing.

Thanks very much to all the beta testers that put their vehicles at risk to help make this a smooth release. There are always a few small issues but hopefully nothing too serious (knock-on-wood). The dev team is standing by to jump on things if they should occur. Thanks again!


Congratulations ! Yipee ! 3DR and DJI move over ! Here is the Ardupilot dream team !

Many thanks to the ArduCopter developers for bringing out this release.

@rmackay9: Just to add to the known issues list, I can verify that on PixRacer not only DSM cannot bind but even plain PPM transmitters/receivers (like the FlySky FS-i6s I use) do not work at all. The radio calibration screen reports 0 on all controls even after a full factory reset.

Downgrading to AC 3.3.4 everything works as expected.
I am going to try and build AC 3.4-rc6 where everything worked as it should and wait for AC 3.4.1 to fix PixRacer radio issues.

Same issue as Frontier. Pixracer PPM no longer functions.
10/15, 20:10
Is the last version that works for me.

I have encountered the same issue on my Pixracers. PPM input no longer works with the FlySky FS-i6s receiver. Reverting back to 3.3 chain does work.

For the FlySky issues, I’ve created an issue here and Tridge is going to look at it as a top priority. We are a bit short of pixracers on the core dev team but PhillipK is going to help us with that.

Can you tell me which receivers you’re using and is this an RC14 board or RC12? The RC14 appearently has a little label on the board somewhere. Maybe post the answer over in the issue linked above?

I’m using a DTF UHF receiver, and its PPM isn’t working.
Receiver is running OpenLRSng
v14 board

As I mentioned above, 10/15, 20:10 is the last version that worked for me, if that helps narrow down the issue.
(I don’t have an account on github, so haven’t posted this there)

Hi Randy,

I can confirm Spektrum Satellite works, Binding Spektrum
DSMx Sats works, SRXL (AR7700) works, PPM fails (AR7700), FrSky SBus (X4R-SB) works.

Looks like it’s working now.
Thanks a lot!

AC 3.4.1 fixed the PPM issue with my FS-i6S, it works like it should.
Thank you for the quick fix.

Hi Randy,

using MP 1.3.41 I have no longer Radio IN at the FailSafe screen, no bars in Radio Calibration and no ch…in in Status since I updated to 3.4.1 heli. These screens work using 3.3.3 heli.
BRD_SBUS_OUT=1 doesn’t work for me, no matter which version. Any suggestions what I should do to get SBUS signal ?

Thanks, Randy!

Where can we find documentation on how to activate the polygon fence through Mavlink? (without mission planner)

A post was split to a new topic: AC 3.4.1 Nick/Roll Issues on Pixracer

I have been trying to figure out if a “PX4
software low pass filter on the SBUS input” for RSSI has been
implemented in ArduCopter 3.4 like the PX4 website claims it has in
their config. (
The only information I can find in Ardupilot is that an external
filter is still required. Is this the case? If so are there plans to
implement this in the future?


I’m not sure of what the sbus input is for but it sounds similar to something we already have. Copter has separate filtering on roll/pitch and throttle regardless of the type of receiver.

Maybe give this a try and see if it’s what you’re looking for?

Randy, Specifically this question is referring to the analog RSSI (PWM) output from a FrSky receivers and others being input to a pixhawk or pixracer to measure the 3.3v analog for RSSI. In the arducopter documentation is shows an old APM taking this signal and needing an external DC lowpass filter to turn the PWM out from FRSky receivers and turning it into a base DC voltage. After pixhawk came to be the standard this signal is taking in on the SBUS out pin (103 on pixhawk) which is right next to the RC in pin on the pixhawk. All the forums that I search I still find people implementing this with pixhawk and still using an external dc filter (10uF capacitor and resistor) to filter out the PWM that the FRSky receivers output for RSSI. looking at the pixhawk site ( it sounds like this has all been considered and implemented in the hardware. It also looks like it may need an implementation in the code. This is the question I have. This may be taken care of int he PX4 modules. Not sure.

Thanks again Randy.


We don’t use a low pass filter, but we do use an average of the value. Now, according to and the X8R doesn’t actually even output PWM since a firmware update quite a time ago. Even if you use a receiver that outputs PWM I think that it won’t work as it is expecting an analog voltage signal - but why don’t you test it?

Thanks for the information. I am using the X4RSB so I think I will probably be facing the issue in the later X8R firmware when trying to pull what FrSky states is PWM from the pad on the RX board. I will implement the spare Channel PWM option which I do believe is now supported in Copter. Thanks again.

hey Randy, i’ve been flying rc6 for ages it seems and finally decided to flash ac3.4.1
it looks as oneshot125 at least on y3 frame doesn’t work in that AC release, though it works with 3.4rc6 (at least used to work prior to update).
normal pwm and regular oneshot work.