Stepper motor home position

I am working with the stepper motor linked below, in a project to align the motor at the position of a PIR sensor. The aim is to design a motion following camera base.

http://bildr.org/2011/06/easydriver/

How to make the stepper motor remember the location of the PIR sensor ??
or how to set a home position for the stepper motor.

Kind regards.

How to make the stepper motor remember the location of the PIR sensor ??

Does your stepper motor really remember anything?

or how to set a home position for the stepper motor.

Stepper motors do not have home positions.

You want the Arduino to remember where it has made the stepper motor move to. You need to assure that the stepper does not move when the Arduino is not paying attention (turned off/being reset/etc.).

If you can not do that, you need to devise some means of knowing where the stepper motor is relative to some known location. Limit switches are the usual solution.

Steppers don't have a home position You have to add a home switch or other sensor (photo-interrupters are common) to let the Arduino know that your motor is at the home position. Then you step until you reach the home position.

These links may be useful

Stepper Motor Basics
Simple Stepper Code

...R