Texas Instruments C28 Series

Quadrature Encoder Pulse (QEP)
What is an Incremental
What is an Incremental
Quadrature
Quadrature
Encoder?
Encoder?
A digital (angular) position sensor
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
How is Position Determined from
How is Position Determined from
Quadrature
Quadrature
Signals?
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.
C28x - Event Manager 7 - 33