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CHAPTER 4 PORT FUNCTIONS
User’s Manual U19780EJ2V0UD
97
4.2.4 Port 3
78K0/KB2-A 78K0/KC2-A
P31/INTP5/OCD1A (/SCK10)
P32/INTP4/OCD1B (/SI10)
−
P33/TI51/TO51/INTP
−
P34/TI50/TO50/INTP2
P35/SO10/INTP1
Remark
The functions of pins whose names are in parentheses can be used by setting bit 2 (ISC2)
of the input switch control register (ISC) to 1.
Port 3 is an I/O port with an output latch. Port 3 can be set to the input mode or output mode in 1-bit units using
port mode register 3 (PM3). When the P31 to P35 pins are used as an input port, use of an on-chip pull-up resistor
can be specified in 1-bit units by pull-up resistor option register 3 (PU3).
This port can also be used for external interrupt request input, timer I/O, serial interface data I/O, and clock I/O.
Reset signal generation sets port 3 to input mode.
Figures 4-11 and 4-13 show block diagrams of port 3.
Cautions 1. Process the P31/INTP5/OCD1A (/SCK10) pin as follows, when it is not used when it is
connected to a flash memory programmer or an on-chip debug emulator.
P31/INTP5/OCD1A
(/SCK10)
Flash memory programmer connection
During reset
Connect to V
SS
via a resistor.
On-chip debug
emulator connection
(when it is not used
as an on-chip debug
mode setting pin)
During reset released
Input:
Connect to V
DD
or V
SS
via a
resistor.
Output: Leave
open.
2. To use P31/INTP5/OCD1A (/SCK10) and P35/SO10/INTP1 as general-purpose ports, set serial
operation mode register 10 (CSIM10) and serial clock selection register 10 (CSIC10) to the
default status (00H).
Remark
P31 and P32 can be used as on-chip debug mode setting pins (OCD1A, OCD1B) when the on-chip
debug function is used. For how to connect an on-chip debug emulator (QB-MINI2), see
CHAPTER 26
ON-CHIP DEBUG FUNCTION.