A stepper motor includes a rotor having equally spaced rotor teeth
defining a full step angle, and a stator with stator poles wound with
coils that can be driven in a series of phases so as to magnetically
interact with the rotor to produce stepping motion. The stator poles have
teeth organized into two groups when there is an even number of stator
teeth per pole, or into three groups for an odd number of stator teeth
per pole. The stator teeth have an average pitch different from the
rotor's tooth pitch, but the groups of stator teeth are also displaced
relative to other groups by a specified offset angle of one-half or
one-quarter step to double the number of detent positions, and to
displace such detent positions from full one-phase ON or two-phase ON
positions.