I have a robotic camera head that has a battery, control board, and two stepper motors. I would like to add my own control board in the unit in parallel off the same battery source and drive the same motors. It is easy to add a two or three position switch between the battery and the two boards and connect both to the motors. But I am wondering if the dormant board will get damaged from current running through the motors from the other board since it is still connected to the motors? Any schematics for this? The plan is to have two or three control boards in the units and an external switch to select which board I want to use. I would never use more than one board at any one time.
For background information, the head is a Gigapan Epic Pro head which works very well out of the box for gigapans. I also have a small board that can do much more and it is controlled by an app over Bluetooth and does time-lapse and many more things. So no display or buttons on the unit required. I also want to add a basic Arduino board just to play around with. Like I would like to try programming the camera head to mimic the motion of my smart phone etc.
Grateful for any help or guidance / direction / links.