Datasheet

© 2010 Microchip Technology Inc. DS70135G-page 91
dsPIC30F4011/4012
14.0 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:
• 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> (QEICON<10:8>).
Figure 14-1 depicts the Quadrature Encoder Interface
block diagram.
FIGURE 14-1: QUADRATURE ENCODER INTERFACE BLOCK DIAGRAM
Note: This data sheet summarizes features of
this group of dsPIC30F devices and is not
intended to be a complete reference
source. For more information on the CPU,
peripherals, register descriptions and
general device functionality, refer to the
dsPIC30F Family Reference Manual
(DS70046). For more information on the
device instruction set and programming,
refer to the “16-bit MCU and DSC
Reference Manual” (DS70157).
16-bit Up/Down Counter
Comparator/
Max Count Register
Quadrature
Programmable
Digital Filter
QEA
Programmable
Digital Filter
INDX
Up/Down
3
Encoder
Programmable
Digital Filter
QEB
Interface Logic
QEIM<2:0>
Mode Select
3
(POSCNT)
(MAXCNT)
QEIIF
Event
Flag
Reset
Equal
2
T
CY
1
0
TQCS
TQCKPS<1:0>
2
1, 8, 64, 256
Prescaler
Q
Q
D
CK
TQGATE
QEIM<2:0>
Synchronize
Det
1
0
Sleep Input
0
1
UPDN_SRC
QEICON<11>
Zero Detect
Note: In dsPIC30F4011/4012, the UPDN pin is not available. Up/Down
logic bit can still be polled by software.