There is something I always hated with APM / Pixhawk : it is the initialization of the gimbal .
The fact that no valid PWM (I guess) is outputed by the Pixhawk after the battery connection leads to uncontrolled movements of camera gimbal with the risk to damage the camera lens.
Well there is another problem with gimbal initialization: quite often the gyro calibration is not valid.
With a brushless gimbal and a heavy camera (1kg), the gyro calibration , blue - red led , is corrupted by the gimbal movement when it gets a valid PWM signal.
Is there a way to control when gyro calibration occurs , initialize the PWM outputs with a delay or launch a new gyro calibration via Mission Planner ?
The best way to sort the issues you have is to delay the powering on of the gimbal. I do it in a very basic way, just placed a switch on the power line of the gimbal.
i thought the same thing , I tried to do it by radio control but seems that Pixhawk is limited to control only one relay with the radio , I already use one for the leds.
Anyway thanks for the suggestion
I adopted a more elegant solution than the mechanical switch .
Using a micro the supply voltage to the gimbal is delayed by a certain time allowing Pixhawk to perform gyro calibration without movements from the gimbal and given to the gimbal a valid PWM when the gimbal complete his calibration.
I decide for 15 seconds delay but I could choose obviously any other delay.
Guess that with a resistor and a capacitor a delay in powering up the gimbal could be achieved but the micro is more flexible even if using a 5$ micro for that is a waste.