Detecting stepper motors "zero" position with an Hall Effect Sensor

I am building a robotic rover based on a few Arduinos.
This Rover will have 3 ultrasound sensors, one of which mounted on a stepper motor to scan the area ahead of the rover.
I plan to use a hall effect sensor to detect the " zero " position of this stepper motor.
Details and source code here : fortytwoandnow....