Port 9 - NEC mPD780065 Series Preliminary User's Manual

4.2.9 Port 9

This is a 3-bit input/output port with output latches. Input mode/output mode can be specified for pins P90 to P92
in 1-bit units with port mode register 9 (PM9). For pins P90 to P92, an on-chip pull-up resistor can be specified in
1-bit units with pull-up resistor option register 9 (PU9).
This port can also be used as the serial interface serial data input/output, and serial clock input/output.
RESET input sets the input mode.
Figure 4-11 shows a block diagram of port 9.
WR
PU
RD
WR
PORT
WR
PM
Alternate functions
PU: Pull-up resistor option register
PM: Port mode register
RD: Port 9 read signal
WR: Port 9 write signal
CHAPTER 4 PORT FUNCTIONS
Figure 4-11. Block Diagram of P90 to P92
PU90 to PU92
Selector
Output latch
(P90 to P92)
PM90 to PM92
Preliminary User's Manual U13420EJ2V0UM00
V
DD0
P-ch
P90/SCK31,
P91/SO31,
P92/SI31
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