What is stepper motor ?
stepper motor is a Brush-less DC motor that rotates with step-by-step making certain specified minimum angle . To make a rotation of stepper motor we need to give a certain command to excite any coil inside stepper motor you want .
as shown in figure you can excite coil in two way either full steps (two coil need to charge at a time ) or half steps angle rotation (one at a time ) .
This is equivalent to following stepping command we actually give from microcontroller for half step angle
and for full angle step commends to give to stepper motor are
the complete project can be down load from this link stepper_motor_with_avr