The jstepper library provides routines for 4-phase unipolar stepper motors.
The provided routines are:
procedure stepper_motor_full_forward( byte in out x )
procedure stepper_motor_half_forward( byte in out x )
procedure stepper_motor_full_backward( byte in out x )
procedure stepper_motor_half_backward( byte in out x )
The stepper motors coils are assumed to be activated by a logical high value. The full step routines take less code than the half step routines. The full step routines can handle 2-coil exitation. Only the lower 4 bits of x should be used, the higher bits are ignored on input and will contain 0 on output.