QA
QB
QCLK
QDIR
QPOSCNT
OV/UF
QA
QB
QCLK
QDIR
QPOSCNT
OV/UF
1
2
3
4
0
1
2
1
0
4
3
2
1
0
4
3
2
1
2
3
4
0
1
0
4
3
2
1
0
1
2
3
4
0
1
2
3
4
0
1
0
4
3
Basic Operation
1968
SPNU563A – March 2018
Copyright © 2018, Texas Instruments Incorporated
Enhanced Quadrature Encoder Pulse (eQEP) Module
34.2.2.3.1.2 Position Counter Reset on Maximum Position (QEPCTL[PCRM] = 01)
If the position counter is equal to QPOSMAX, then the position counter is reset to 0 on the next eQEP
clock for forward movement and position counter overflow flag is set. If the position counter is equal to
ZERO, then the position counter is reset to QPOSMAX on the next QEP clock for reverse movement and
position counter underflow flag is set.
shows the position counter reset operation in this mode.
First index marker is defined as the quadrature edge following the first index edge. The eQEP peripheral
records the occurrence of the first index marker (QEPSTS[FIMF]) and direction on the first index event
marker (QEPSTS[FIDF]) in the QEPSTS registers; it also remembers the quadrature edge on the first
index marker so that the same relative quadrature transition is used for the software index marker
(QEPCTL[IEL]=11).
Figure 34-9. Position Counter Underflow/Overflow (QPOSMAX = 4)