Stepper motor controller is needed to run a stepper motor, since a stepper motor cannot work by just connecting it to a power supply.  To program a stepper motor to make a complex movement, we usually need a micro controller. Fortunatelly, for a simple movement like just rotating eith a constant speed, we can use avery simple circuit as described here. Here is the schematic diagram of the controller circuit:

simple stepper motor control circuit schematic

This stepper motor controller circuit still need an external input. If we look at the table, the input pattern is similar to a 2 bits binary counter.  If you have an up-down binary counter, then you get a forward-reverse control for your stepper motor.