actually what the main use of pwm in stepper motor control using uC? i sometimes hear of motor drivers(e.g. Uln2003) for control of motors, in other instances i hear of PWM. i'm little confused.
Not really no, PWM is used for DC motors, it 'can' be used as part of the stepping process to limit the current to a stepper - but isn't very common, and for a completely different reason.