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Copter-3.6.12 has been released! Critical Safety Update if you are flying 3.6.10 (or older)

Copter-3.6.12 has been released as the official default software for MultiCopters and Helicopters.

For those flying 3.6.10 (or earlier) the upgrade is Critical to avoid possible lockups due to I2C storms. These situations are rare but we have seen enough of them that we strongly recommend upgrading.

For those flying 3.6.11, your vehicle is probably safe but we still recommend upgrading to 3.6.12 because it includes a fix to another rare case of I2C storm lockups caused by extreme interference on the bus. We have one reported case which involved a serial port inadvertently connected to an I2C port.

The upgrade from earlier versions of 3.6.x should be relatively painless with no re-calibrations required unless you see pre-arm checks prompting you to do so.

The two new changes in 3.6.12 are in the ReleaseNotes and copied below.

  1. Fix ChibiOS I2C DMA error
  2. COMPASS_SCALE param to allow manual correction of compass scaling

The second issue allows users to work around a compass scaling issue with the Hex Here2 GPS/compass unit. The Here2 compass unit’s scaling is off by about 17% meaning setting COMPASS_SCALING = 1.17 should improve accuracy. The accuracy can be checked before and after this change by:

  • fly the vehicle in any mode but ensure the flight includes chaning the vehicle’s heading
  • download the dataflash log and check the NKF4.SM values which are the compass’s “innovations” (the difference between the expected values and actual values). Lower is better so hopefully Here2 users will see lower values after setting the COMPASS_SCALE value to 1.17.

Note: beta testing of Copter-4.0.0-rc3 will resume next monday (Dec 16th).


Hey @rmackay9
Can we have this on top of Home page like in CubePilot? So that most people who visit are aware and upgrade!

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It’s the top blog on at the moment and I’ve also “pinned” the discussion so it’s at the top of the Copter-3.6 section of discuss but I’ll bring up on the dev call tomorrow the idea of adding a banner to the top of and/or the discuss forums.

We’re talking about how to make it more visible to people, another suggestion is we add a link to the release notes when the MP pops up the “a new version is available” box.


Yes. Adding link to MP pop-up is a great idea.

The bottom line is that I use r9mm, for this, yaapu script is installed on taranis x7. For this bundle to work, I solder the wire to tx uart 2 and solder to r9mm. In serial 2 I set protocol 10 and there is an item in the developer firmware (4.0 dev) in setting up the show option! I choose option 7. And then telemetry works, very well with a small delay.

And the question is how to do the same but in stable firmware, because there is no option there.

So If I have Here 2 GPS with compass. I should update the firmware to 3.6.12 and change parameter:
There is no such parameter there is only COMPASS_SCALE and If I try to change it to 1.17 Mission Planner is telling me that it’s “Bad number”


Sorry for the slow response, that was a typo in the explanation above. COMPASS_SCALE (not _SCALING) should be set to 1.17 if using the Here2 with Copter-3.6.12.

I’ve just done a quick test with a CubeBlack running Copter-3.6.12 and using beta mission planner and I was able to set the COMPASS_SCALE parameter to 1.17. The “bad number” message from Mission Planner normally means that there’s an issue with the characters entered. For example some European countries use a comma (",") instead of a period (".") so perhaps this is the issue.

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