Driving Stepper Motors: KISS

Used a great deal in robotics, where it is a direct competitor for DC motors and radio-control servos, the stepper motor does however suffer from the comparative difficulty encountered in driving it. Unlike its DC equivalents, which rotate as soon as power is applied, the stepper motor requires a succession of pulses applied to its various windings to make it turn. On the other hand, and provided its mechanical capacities are not exceeded, the number of basic steps moved by the motor corresponds to the number of pulses applied to its windings. Hence in this way we have available virtually automatic positioning information, impossible to obtain with a DC motor.

Lp293 spec. sheet :

http://www.st.com/stonline/books/pdf/docs/1328.pdf