Strange startup

Hi, All

My PixHawk appears to be functioning properly with a strange action on startup: when Armed, the motors immediately spin - not fast enough to fly, but this is very disconcerting. Futhermore, if I let them spin they will slowly stop after a minute or so. If I Disarm it after they stop and Arm it once again they sit there stopped and everything seems normal. FWIW, if I fly it at this time all modes appear to work normally but Loiter, where it drifts around quite a bit.

I tried to fly it after this weird startup (Green LED) and in Stabilize it just shot up with no control. I don’t know what I did at the time (panic :open_mouth: ) but I got the motors to stop and let it crash…no damage as it was on grass and didn’t get too high.

Here’s what I’ve done - performed all calibrations several times, reloaded firmware several times, calibrated the ESC’s many times, both through the PixHawk and manually one by one. It still persists in this abnormal behaviour. I also swapped it with my 3DR APM 2.6 machine which works perfectly and it still plays this Armed game. So, the only difference is the PixHawk on either frame. Same motors, same ESCs.

Any thoughts or conclusions will be very much appreciated! :slight_smile: I’m sure it’s something I’ve done, but can’t figure it out for the life of me.



This caught me by surprise too!

It is intentional, and was added as a default parameter for safety. I think it is a great idea, but perhaps the warnings weren’t sufficient to let people know.

There is a parameter called MOT_SPIN_ARMED with a few possible values, including OFF if you don’t like it. I turned it off for a while as I was building my Quad (lots of arming and disarming while testing), but now that it is stable, I turned it back on. The benefit is that bystanders are given a relatively safe but very clear indication that the unit is armed - the LED alone may be enough to alert YOU, but probably won’t keep someone from running up to it right as you hit the gas.

Thank you SOOOOO much for this info. It proves that I still have a lot to learn about this device. :blush: