I’m using fc Matek H743-Wing with Arduplane 4.1. When I power on the plane, it takes about 14 seconds for the fc to boot up. While booting, no pulse signal is sent to the servos (I checked with a scope) and once boot finished, Ardupilot starts sending the pulse.
My problem is that if my servos receive no pulse, they go violently to a maximum position and for one of them (the steering for my front wheel plane) it breaks the rod; so I have to find a solution so that the servo stays at the neutral position during boot-up.
Is there a way with Ardupilot to disable voltage on servos during boot-up and power on servos only when ardupilot is ready to send pulse?
Else, is there a way to tell a servo its default position when powered on and no pulse received?
Try using different servos. Servos should not move without a PWM signal at all. It is also possible, that you have a (somewhat) defective unit.
I am not sure if it would make a difference, but one thing you could try is to connect a pull down resisor to the PWM signal. Maybe it doesn´t like it if you leave it floating.
I tried with a couple of different servos I had here (different make/models) and I’m getting the same behavior.
I also tried to put the signal pin to ground and I’m getting the same behavior as well.
So, finally, I managed to adjust it mechanically so that it will not break the rod anymore even if it is going to the maximum position.
@gplante2 Did you find a solution to this? I have just done a setup with a h743 wing and have the same issue. Super annoying. Also my esc gets disabled when it receives power but no pulses. It does not come back alive once the pwm is back. I need to power up the fc first and then the esc.
Based on the most recent discussion here, it sounds like the servos were moving independent of any autopilot or receiver input at power-up. In that case, there is no software solution. It is a hardware problem.