T
0
0.25T
0
±0.1T
0
0.5T
0
±0.1T
0
T
0
±0.5T
0
QEPA
QEPB
QEPI
(gated to
A and B)
QEPI
(gated to A)
QEPI
(ungated)
T
0
0 1 2 3 4 5 6 7 N−6 N−5 N−4 N−3 N−2 N−1
0
QEPA
QEPB
QEPI
Clockwise shaft rotation/forward movement
Anti-clockwise shaft rotation/reverse movement
0 N−1 N−2 N−3 N−4 N−5 N−6 N−7 6 5 4 3 2 1 0 N−1 N−2
QEPA
QEPB
QEPI
T
0
Legend: N = lines per revolution
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Enhanced Quadrature Encoder Pulse (eQEP) Module
Figure 15-130. QEP Encoder Output Signal for Forward/Reverse Movement
Quadrature encoders from different manufacturers come with two forms of index pulse (gated index pulse
or ungated index pulse) as shown in Figure 15-131. A nonstandard form of index pulse is ungated. In the
ungated configuration, the index edges are not necessarily coincident with A and B signals. The gated
index pulse is aligned to any of the four quadrature edges and width of the index pulse and can be equal
to a quarter, half, or full period of the quadrature signal.
Figure 15-131. Index Pulse Example
1651
SPRUH73H–October 2011–Revised April 2013 Pulse-Width Modulation Subsystem (PWMSS)
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