3.3.0beta1 Pixhawk Servo Power Issue?

I’m having an issue with 3.3.0beta1. 3.2.3 works without issue, but when I update to 3.3.0beta1, my servos no longer seem to be getting power from the Pixhawk. My setup is a Pixhawk in a Parkzone Sport Cub S2, using a Spektrum Satellite as a receiver, plugged directly into the DSM port, and with a BEC plugged into port 8 on the Pixhawk. The radio is properly bound, and I can confirm it is not a radio problem because when I am connected to Mission Planner via telemetry, flipping my mode switch results in a voice notification from the computer that my mode has changed (to the correct mode that it should be, as well). Radio calibration works as well, and I see my outputs on the screen for all channels. This is all while powered off the battery/BEC and running over wireless telemetry, not plugged in to USB.

But when I arm, I get no response out of the control surfaces or the throttle. It’s the exact same behavior I had when I first hooked the system up and didn’t realize my ESC wouldn’t power the Pixhawk and I needed to add a BEC. Either way, the only way I figured out to fix the issue was to not only downgrade back to 3.2.3, but also nuke the settings back to default and set the airplane up from scratch again. The fix does not require any change in hardware configuration. I confirmed that by going through the whole process again. Just downgrading to 3.2.3 does not seem to fix the issue, I have to actually reset all parameters to default as well.

Is there a new parameter somewhere in 3.3.0 that I need to flip in order to power the servos that I’m just aware of, or should I file a bug report in github? I am sort of assuming that I am just missing something, but maybe not?

It would be great if you could post both the tlog’s from whatever ground station your using and the data flash .bin logs whilst you experience the issue. We can then have a look and see what’s going on.
There hasn’t been a great deal of changes since the 3.2.3 release so it is odd.
I would also try powering the pixhawk from a port other then 8 - just to see if that makes a difference.

Thanks, Grant.

I didn’t capture the logs at the time because I was just trying to go fly. I’ll try to make time to go through the process again this weekend and capture it.

The first (or maybe second) thing I tried was different pins for the BEC wire. No dice. I get no power regardless of what pin it is connected to.

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I faced a similar problem with Pixhawk and ArduPlane 3.2.2 and 3.2.3. After radio calibration (using a Spectrum satellite receiver and a DX6i), the outputs were not working any more. Turns out that during the calibration, the parameter value RC8_TRIM=0 was stored (channel 8 is not available in my setup). After setting the parameter to a valid value (1500), the outputs work as expected.

I do not recommend that you use only the Spektrum Remote Receiver with the Pixhawk in your plane unless it is a park flyer. The Remote Receiver does not have sufficient enough range compared to a full up receiver. Be smart and use a full up receiver and a PPM encoder and avoid the loss of your plane.