W79E217A Datasheet, PDF (137/207 Pages) Winbond – 8-bit Microcontroller

Preliminary W79E217A Data Sheet
CURRENT
SIGNAL
DETECTED
QEA rising
QEA falling
QEB rising
QEB falling
QEA
9
9
PREVIOUS SIGNAL DETECTED
RISING
FALLING
QEB
QEA
QEB
9
9
9
9
9
9
Table 15-1: Direction of count
COUNTING
CONTROL
(DIR)
INC (1)
DEC (0)
DEC (0)
INC (1)
INC (1)
DEC (0)
INC (1)
DEC (0)
Figure 15-12: X4 Counting Mode
QEI x4 Counting mode provides for a finer resolution of the rotor position, since the counter
increments or decrements more frequently for each QEA/QEB input pulse pair than in QEI x2 mode.
This mode is selected by setting the QEI Mode Select bits to ‘00b’ or ‘10b’. In this mode, the QEI logic
detects every edge on every QEA and QEB input edges.
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Publication Release Date: December 14, 2007
Revision A3.0