How to implement a signal output (variable value) to usb in an android application?

Question

Android

Actually a subject.
It is required to create an application for a tablet that will be constantly connected via usb to the controller that receives the signal.
A password is entered on the tablet, if it is correct, a signal is sent to the self-made controller via usb. For example FFFF.
Is it possible to? And if possible, in which direction to dig?
Thanks in advance.

Answer 1

How about using bluetooth (HC-05 modules and the like) to organize such a joy?
On USB, not in OTG mode, you will have to make crutches, and on the second end you will need a controller that can keep running Linux and adb.