© 2004 Microchip Technology Inc. DS70063C-page 16-3
Section 16. Quadrature Encoder Interface (QEI)
Quadrature Encoder
Interface (QEI)
16
The Quadrature Encoder Interface (QEI) module provides an interface to incremental encoders.
The QEI consists of quadrature decoder logic to interpret the Phase A and Phase B signals and
an up/down counter to accumulate the count. Digital glitch filters on the inputs condition the
input signal. Figure 16-2 depicts a simplified block diagram of the QEI Module.
The QEI module includes:
• Three input pins for two phase signals and index pulse
• Programmable digital noise filters on inputs
• Quadrature decoder providing counter pulses and count direction
• 16-bit up/down position counter
• Count direction status
• X2 and X4 count resolution
• 2 modes of position counter reset
• General Purpose16-bit timer/counter mode
• Interrupts generated by QEI or counter events
Figure 16-2: Quadrature Encoder Interface Module Simplified Block Diagram
Quadrature
Decoder
Logic
UPDN
16-Bit Up/Down
Counter
QEB
Digital
Filter
QEA
CLOCK
DIR
Clock
Divider
TCY
INDX
Digital
Filter
Digital
Filter
Comparator/
Max Count Register
(MAXCNT)
Reset
EQUAL
Zero Detect
(POSCNT)
To Next Page
Loading...
