eQEP Registers
1985
SPNU563A – March 2018
Copyright © 2018, Texas Instruments Incorporated
Enhanced Quadrature Encoder Pulse (eQEP) Module
34.3.13 eQEP Decoder Control Register (QDECCTL)
Figure 34-33. eQEP Decoder Control Register (QDECCTL) [offset = 2Ah]
15
14
13
12
11
10
9
8
QSRC
SOEN
SPSEL
XCR
SWAP
IGATE
QAP
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
7
6
5
4
0
QBP
QIP
QSP
Reserved
R/W-0
R/W-0
R/W-0
R-0
LEGEND: R/W = Read/Write; R = Read only; -
n
= value after reset
Table 34-16. eQEP Decoder Control Register (QDECCTL) Field Descriptions
Bits
Name
Value
Description
15-14
QSRC
Position-counter source selection.
0
Quadrature count mode: (QCLK = iCLK, QDIR = iDIR).
1h
Direction-count mode: (QCLK = xCLK, QDIR = xDIR).
2h
UP count mode for frequency measurement :(QCLK = xCLK, QDIR = 1).
3h
DOWN count mode for frequency measurement: (QCLK = xCLK, QDIR = 0).
13
SOEN
Sync output-enable.
0
Position-compare sync output is disabled.
1
Position-compare sync output is enabled.
12
SPSEL
Sync output pin selection.
0
Index pin is used for sync output.
1
Strobe pin is used for sync output.
11
XCR
External clock rate.
0
2x resolution: Count the rising/falling edge.
1
1x resolution: Count the rising edge only.
10
SWAP
Swap quadrature clock inputs. This swaps the input to the quadrature decoder, reversing the
counting direction.
0
Quadrature-clock inputs are not swapped.
1
Quadrature-clock inputs are swapped.
9
IGATE
Index pulse gating option.
0
Disable gating of Index pulse.
1
Gate the index pin with strobe.
8
QAP
QEPA input polarity.
0
No effect.
1
Negates QEPA input.
7
QBP
QEPB input polarity.
0
No effect.
1
Negates QEPB input.
6
QIP
QEPI input polarity.
0
No effect.
1
Negates QEPI input.
5
QSP
QEPS input polarity.
0
No effect.
1
Negates QEPS input.
4-0
Reserved
0
Always read as 0.