Microchip Technology dsPIC30F - What is a Quadrature Encoder?

dsPIC30F Quadrature Encoder Interface Module
© 2005 Microchip Technology Inc.
Page 3
© 2005 Microchip Technology Incorporated. All Rights Reserved. dsPIC30F Quadrature Encoder Interface Module 3
What is a Quadrature Encoder?
slotted wheel
light source
sensing device
logic
A Quadrature Encoder (or incremental encoder, or optical encoder) is used to
detect the position and speed of rotors, enabling closed loop control in many
motor control applications like switched reluctance and induction motors.
Typically, an encoder includes a slotted wheel attached to the motor shaft, a
light source, a light sensing device and some logic. During the rotation of the
shaft, the light passes through the slots and hits the sensing element,
generating electric signals.
The three digital outputs are called Phase A, Phabe B and Index. With some
decoding performed by the dsPIC quadrature encoder interface, these signals
can tell us the speed and position of the rotor.