Copter-3.5.6 released!

Copter-3.5.6-rc1 has been out for a few days and no issues reported so we’ve released it as the official version.

The changes vs 3.5.5 are in the ReleaseNotes and also listed below.

  1. Safety switch fix to refuse presses once armed (BRD_SAFETYOPTION controls behaviour)

The change is also demonstrated in the video below:

Thanks to those who gave Copter-3.5.6-rc1 a try!

Hello everyone,

It seems that there is a small issue with the ESC calibration on version 3.5.6:
When BRD_SAFETYOPTION = 3, the ESC calibration is not working as described in “All at once calibration” section on this page :

When pressing the safety button, it doesn’t becomes solid red but continues to blink and the ESC’s are not calibrating.

To bypass this we need to set the BRD_SAFETYOPTION = 7, proceed with the ESC calibration, and then set it back to BRD_SAFETYOPTION = 3


Thanks for the report. Damn… if only this had been found in beta testing… I’ll try and recreate the issue and then we will likely release 3.5.7-rc1…


Could I ask you to test Copter-3.5.7-rc1 and report back whether the ESC calibration is working for you or not? I’ve tested it so I’m pretty sure it works but it would be nice to have at least one other person test it.

Hi Randy,
I confirm that ESC calibration works again as it should in version 3.5.7-rc1.
It was tested with the “All at once calibration” procedure (as explained in page : and also with the “ESC calibration” menu in MP and.
Thank you for the correction.

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wk, great, thanks very much for that!

i glanced through 3.6 notes, i would like to confirm this change is in the release candidates for 3.6


yes, definitely. The safety switch change is included in all the recent Copter-3.6.x release candidates.

I not 100% esc calibration is working right I not getting the rotating sounds like the old version only sounds like one esc is working/beeping. I miss the full consort of tones. Could be just my ZTW esc’s not sounding off.

does this also prevent arm/disarm assignment to an RC channel from disarming in flight?


No, it doesn’t. There’s a de-bounce added to the auxiliary switches in Copter-3.6 but still, if the pilot demands a disarm from an auxiliary switch, it always obeys.