Armed but motors not spinning


I recently ordered a Pixhawk 4 Mini, and have set everything up in QGroundControl now and built my new quad. I’ve got the point where the pixhawk arms, and I get no warnings/errors.

I then decided to test the motors were spinning the right way but no matter what I try I can’t seem to get them to spin up. I’ve checked the safety switch is disabled (22027) and that everything is calibrated. Have also checked the hardware setup with my old APM2.8 and everything spins and works so it doesn’t appear to be a hardware issue…

I’ve stuck an oscilloscope on the output pins and I don’t see any PWM outputs on any of the pins, which I think is where my issue is. For some reason the outputs seem to be disabled? Not sure if the board might be faulty or I’m just doing something wrong (Have checked that I don’t have the signal pins upside down as I’ve noticed the outputs are upside down compared to the regular Pixhawk 4).

Any suggestions? I’m running out of ideas now!

Hi, could you please access the mavlink shell in QGroundControl and run the following commands:
pwm info
fmu status
Moreover what airframe did you select for your setup? Quad x? And what version of px4 are you running? Is it what came with the Pixhawk or did you reflash it?

This will help to understand what is mapped to the outputs.

Hi Daniele,

Interesting pwm info resets the pixhawk, which probably isn’t a good sign.

fmu status returns:

INFO [fmu] Running as task
INFO [fmu] RC scan state: SBUS
INFO [fmu] PWM Mode: pwm8

It’s set up as a Quadroter X with firmware version 1.8.2. This was what it got flashed too when I first ran the setup in QGC.

I am having the same problem with no motors responding and the pwm info resets. The fmu status gives the same results.

Are you using the new pixhawk mini too?

If so the fix is to use the v1.9 master firmware, I was told the 1.8.2 stable was released before the mini came out so you have to run the test version until the new version is released.

I just installed the v1.9 master firmware and now I get many data lost and other messages that I did not get before. I’ll keep trying but did you have this problem as well?

You’ll have to recalibrate your controller from the start if you haven’t already I think that might be your issue?

Where did you download v1.9?

I recalibrated v1.9 and it works good but I almost cut off my middle finger because I did not have a arm switch programmed.
Thank you very much.

If it makes you feel any better when I was first flying this one I dropped the throttle too quickly and stupidly tried to catch it and cut my hand up… Never did that again lol…