Oki MSM85C154HVS - Serial Port Application Examples; I;O Extension

MSM80C154S/83C154S/85C154HVS
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4.6.4 Serial port application examples
4.6.4.1 I/O extension
I/O extension can be achieved by using the serial port in mode 0. An input extension example
is shown in Figure 4-37 and the corresponding timing chart is shown in Figure 4-38.
Following output of the latch pulse from PX.X, REN=“1” and R1=“0” are set for shift in of 74LS1
65 data.
MSM80C154S
MSM83C154S
PX.X
RXD
TXD
QH
HGFEDCBA
INHIBIT CK
74LS165
CLOCK
SERIAL IN
SHIFT/LOAD
INPUT
VCC
Figure 4-37 Input extension example
74LS165-QH
TXD
RX.X
Figure 4-38 Input extension example timing chart