it is simple... the processor does not even need to control the motor. port pins and pull up resistors is all you need. the primary control is simply direction and one pulse per step.
what is there to not understand?
If you really must you should check out the manufacturer before asking for help:
Actually its just one part of my whole project. There is some logic input to the controller and the controller will in turn drive the stepper motor through a3982. Now I just have a doubt that only the step and dir pins should be connected to controller or anyelse for operation???