Texas Instruments C2000 Workshop Guide And Lab Manual

eQEP
C2000 Microcontroller Workshop - Control Peripherals 7 - 43
eQEP
What is an Incremental Quadrature
Encoder?
A digital (angular) position sensor
slots spaced θ deg. apart
photo sensors spaced θ /4 deg. apart
light source (LED)
shaft rotation
Ch. A
Ch. B
Quadrature Output from Photo Sensors
θ
θ
/4
Incremental Optical Encoder
The eQEP circuit, when enabled, decodes and counts the quadrature encoded input pulses. The
QEP circuit can be used to interface with an optical encoder to get position and speed information
from a rotating machine.
How is Position Determined from
Quadrature Signals?
Ch. A
Ch. B
(00)
(11)
(10) (01)
(A,B) =
00
01
11
10
Quadrature Decoder
State Machine
increment
counter
decrement
counter
Position resolution is θ /4 degrees
Illegal
Transitions;
generate
phase error
interrupt

Texas Instruments C2000 Specifications

General

Brand	Texas Instruments
Model	C2000
Category	Microcontrollers
Language	English