New Mission Module

Hi all, I want to create a new module for package delivery that controls pwm of aux in mission mode or there could be a new mode, also i want it to check for battery status. I know how uORB works creating new messages receiving publishing etc. Also implementing new mavlink new messages. But i haven’t created any full functional module before. Is there any tutorial or something that i can follow or any suggestions?

Thanks in advance.

I am using PX4 version 1.12