QEI Registers
1575
SLAU723A – October 2017 – Revised October 2018
Copyright © 2017–2018, Texas Instruments Incorporated
Quadrature Encoder Interface (QEI)
Table 24-3. QEICTL Register Field Descriptions (continued)
Bit
Field
Type
Reset
Description
8-6
VELDIV
R/W
0x0
Predivide Velocity. This field defines the predivider of the input
quadrature pulses before being applied to the QEICOUNT
accumulator.
0x0 = /1
0x1 = /2
0x2 = /4
0x3 = /8
0x4 = /16
0x5 = /32
0x6 = /64
0x7 = /128
5
VELEN
R/W
0x0
Capture Velocity.
0x0 = No effect.
0x1 = Enables capture of the velocity of the quadrature encoder.
4
RESMODE
R/W
0x0
Reset Mode.
0x0 = The position counter is reset when it reaches the maximum as
defined by the MAXPOS field in the QEIMAXPOS register.
0x1 = The position counter is reset when the index pulse is captured.
3
CAPMODE
R/W
0x0
Capture Mode. When SIGMODE = 1, the CAPMODE setting is not
applicable and is reserved.
0x0 = Only the PhA edges are counted.
0x1 = The PhA and PhB edges are counted, providing twice the
positional resolution but half the range.
2
SIGMODE
R/W
0x0
Signal Mode.
0x0 = The internal PhA and PhB signals operate as quadrature
phase signals.
0x1 = The internal PhA input operates as the clock (CLK) signal and
the internal PhB input operates as the direction (DIR) signal.
1
SWAP
R/W
0x0
Swap Signals. Note if the INVA or INVB bit are set, the inversion of
the signals occur prior to the swap.
0x0 = No effect.
0x1 = Swaps the PhAn and PhBn signals.
0
ENABLE
R/W
0x0
Enable QEI. After the QEI module has been enabled by setting the
ENABLE bit, it cannot be disabled. The only way to clear the
ENABLE bit is to reset the module using the Quadrature Encoder
Interface Software Reset (SRQEI) register.
0x0 = No effect.
0x1 = Enables the quadrature encoder module.