QEI Registers
1574
SLAU723A – October 2017 – Revised October 2018
Copyright © 2017–2018, Texas Instruments Incorporated
Quadrature Encoder Interface (QEI)
24.5.1 QEICTL Register (Offset = 0x0) [reset = 0x0]
QEI Control (QEICTL)
This register contains the configuration of the QEI module. Separate enables are provided for the
quadrature encoder and the velocity capture blocks; the quadrature encoder must be enabled in order to
capture the velocity, but the velocity does not need to be captured in applications that do not need it. The
phase signal interpretation, phase swap, Position Update mode, Position Reset mode, and velocity
predivider are all set through this register.
QEICTL is shown in
and described in
Return to
Figure 24-4. QEICTL Register
31
30
29
28
27
26
25
24
RESERVED
R-0x0
23
22
21
20
19
18
17
16
RESERVED
FILTCNT
R-0x0
R/W-0x0
15
14
13
12
11
10
9
8
RESERVED
FILTEN
STALLEN
INVI
INVB
INVA
VELDIV
R-0x0
R/W-0x0
R/W-0x0
R/W-0x0
R/W-0x0
R/W-0x0
R/W-0x0
7
6
5
4
3
2
1
0
VELDIV
VELEN
RESMODE
CAPMODE
SIGMODE
SWAP
ENABLE
R/W-0x0
R/W-0x0
R/W-0x0
R/W-0x0
R/W-0x0
R/W-0x0
R/W-0x0
Table 24-3. QEICTL Register Field Descriptions
Bit
Field
Type
Reset
Description
31-20
RESERVED
R
0x0
19-16
FILTCNT
R/W
0x0
Input Filter Prescale Count. This field controls the frequency of the
input update. When this field is clear, the input is sampled after 2
system clocks. When this field ix 0x1, the input is sampled after 3
system clocks. Similarly, when this field is 0xF, the input is sampled
after 17 clocks.
15-14
RESERVED
R
0x0
13
FILTEN
R/W
0x0
Enable Input Filter.
0x0 = The QEI inputs are not filtered.
0x1 = Enables the digital noise filter on the QEI input signals. Inputs
must be stable for 3 consecutive clock edges before the edge
detector is updated.
12
STALLEN
R/W
0x0
Stall QEI.
0x0 = The QEI module does not stall when the microcontroller is
stopped by a debugger.
0x1 = The QEI module stalls when the microcontroller is stopped by
a debugger.
11
INVI
R/W
0x0
Invert Index Pulse.
0x0 = No effect.
0x1 = Inverts the IDX input.
10
INVB
R/W
0x0
Invert PhB.
0x0 = No effect.
0x1 = Inverts the PhBn input.
9
INVA
R/W
0x0
Invert PhA.
0x0 = No effect.
0x1 = Inverts the PhAn input.