Datasheet

© 2009 Microchip Technology Inc. DS70287C-page 191
dsPIC33FJXXXMCX06/X08/X10
17.0 QUADRATURE ENCODER
INTERFACE (QEI) MODULE
This section 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 the follow-
ing:
• Three input channels for two phase signals and
an 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
The QEI module’s operating mode is determined by
setting the appropriate bits, QEIM<2:0>
(QEICON<10:8>). Figure 17-1 depicts the Quadrature
Encoder Interface block diagram.
FIGURE 17-1: QUADRATURE ENCODER INTERFACE BLOCK DIAGRAM
Note: This data sheet summarizes the features
of the dsPIC33FJXXXMCX06/X08/X10
family of devices. However, 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 Family Ref-
erence Manual”, which is available from
the Microchip web site (www.micro-
chip.com).
16-bit Up/Down Counter
Comparator/
Max Count Register
QEAx
INDXx
0
1
Up/Down
Existing Pin Logic
UPDNx
3
QEBx
QEIM<2:0>
Mode Select
3
(POSCNT)
(MAXCNT)
PCDOUT
QExIF
Event
Flag
Reset
Equal
2
T
CY
1
0
TQCS
TQCKPS<1:0>
2
Q
QD
CK
TQGATE
QEIM<2:0>
1
0
Sleep Input
0
1
UPDN_SRC
QEIxCON<11>
Zero Detect
Synchronize
Det
1, 8, 64, 256
Prescaler
Quadrature
Encoder
Interface Logic
Programmable
Digital Filter
Programmable
Digital Filter
Programmable
Digital Filter