Datasheet

 2009-2012 Microchip Technology Inc. DS70591E-page 257
dsPIC33FJ32GS406/606/608/610 and dsPIC33FJ64GS406/606/608/610
17.0 QUADRATURE ENCODER
INTERFACE (QEI) MODULE
This chapter describes the Quadrature Encoder Inter-
face (QEI) module and associated operational modes.
The QEI module provides the interface to incremental
encoders for obtaining mechanical position data.
The operational features of the QEI include:
• Three Input Channels for Two Phase Signals and
Index Pulse
• 16-Bit Up/Down Position Counter
• Count Direction Status
• Position Measurement (x2 and x4) mode
• Programmable Digital Noise Filters on Inputs
• Alternate 16-Bit Timer/Counter mode
• Quadrature Encoder Interface Interrupts
These operating modes are determined by setting the
appropriate bits, QEIM<2:0> in (QEIxCON<10:8>).
Figure 17-1 depicts the Quadrature Encoder Interface
block diagram.
FIGURE 17-1: QUADRATURE ENCODER INTERFACE x BLOCK DIAGRAM (x = 1 OR 2)
Note 1: This data sheet summarizes the features
of the dsPIC33FJ32GS406/606/608/610
and dsPIC33FJ64GS406/606/608/610
families of devices. It is not intended to be
a comprehensive reference source. To
complement the information in this data
sheet, refer to Section 15. “Quadrature
Encoder Interface (QEI)” (DS70208) in
the “dsPIC33F/PIC24H Family Reference
Manual”, which is available from the
Microchip web site (www.microchip.com).
2: Some registers and associated bits
described in this section may not be
available on all devices. Refer to
Section 4.0 “Memory Organization” in
this data sheet for device-specific register
and bit information.
Note: An ‘x’ used in the names of pins, control/
status bits and registers denotes a
particular QEI module number (x = 1 or 2).
Comparator/
QEAx
(1)
INDXx
(1)
0
1
Up/Down
Existing Pin Logic
UPDNx
3
QEBx
(1)
QEIM<2:0>
Mode Select
3
PCDOUT
QExIF
Event
Flag
Reset
Equal
2
T
CY
1
0
TQCS
TQCKPS<1:0>
2
Q
Q
D
CK
TQGATE
QEIM<2:0>
1
0
Sleep Input
0
1
UPDN_SRC
QEIxCON<11>
Zero-Detect
1, 8, 64, 256
Prescaler
Quadrature
Encoder
Interface Logic
Programmable
Digital Filter
Programmable
Digital Filter
Programmable
Digital Filter
Note 1: The QEI1 module can be connected to the QEA1/QEB1/INDX1
or AQEA1/AQEB1/AINDX1 pins, which are controlled by clearing
or setting the ALTQIO bit in the FPOR Configuration register. See
Section 24.0 “Special Features” for more information.
Synchronize
Detect
16-Bit Up/Down Counter
(POSxCNT)
Max Count Register
(MAXxCNT)