CHAPTER 5 PORT FUNCTIONS
User’s Manual U13045EJ2V0UM00
81
5.2.4 Port 5
This is a 4-bit N-ch open-drain I/O port with output latches. Port 5 can be specified as input or output mode in
1-bit units by using port mode register 5 (PM5). For a mask ROM version, whether a pull-up resistor is to be
incorporated can be specified by the mask option.
RESET input sets port 5 to input mode.
Figure 5-8 shows a block diagram of port 5.
Figure 5-8. Block Diagram of P50 to P53
PM:
Port mode register
RD:
Port 5 read signal
WR:
Port 5 write signal
Caution When using the pins of port 5 as input pins, the input mode must be set with V
DD
= 3.5 to 5.5 V
(when in output mode, pins can be used with V
DD
= 2.7 to 5.5 V).
If V
DD
is less than 3.5 V, the input value may not be read correctly.
Internal bus
Selector
RD
PM50 to PM53
P50 to P53
N-ch
WR
PORT
Output latch
(P50 to P53)
WR
PM
V
DD
Mask option resistor
Mask ROM version only.
For flash memory version,
a pull-up resistor is not
incorporated.
Summary of Contents for mPD789101
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