Stepper Motor Data 2

Types of Stepper Motors
A stepper, or stepping motor converts electronic pulses into
proportionate mechanical movement. Each revolution of
the stepper motor's shaft is made up of a series of discrete individual
steps. A step is defined as the angular rotation produced by the output
shaft each time the motor receives a step pulse.
The most popular types of stepper motors are permanent-magnet
(PM) and variable reluctance (VR).
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Half Stepping

The motor can also be "half stepped" by inserting an off state
between transitioning phases.This cuts a stepper's full step angle
in half.For example,a 90° stepping motor would move 45 on each
half step,
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Typical Stepping Sequence for a Four Phase Stepper Motor

A change in the coil states (ie. changing from state 2 to state 3 as
shown above) results in a single step of the motor shaft. Direction
is easily controlled by running through the above sequence either
forward or backward. It should also be noted that the coils A and A'
are always oppositely charged, as are coils B and B'. By inverting
the signals going to coils A and B, the corresponding signals A' and B'
can be attained. Thus, only two control lines are required to place
the motor into any one of the 4 possible states.
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