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CHAPTER 4 PORT FUNCTIONS
User’s Manual U19780EJ2V0UD
85
4.2.2 Port 1
78K0/KB2-A 78K0/KC2-A
P10/TxD6/TI51/TO51 P10/TxD6
P11/RxD6/TI50/TO50 P11/RxD6
P12/TOH0/INTP7/TI000 P12/TOH0/INTP7
P13/TOH1/INTP6/TI010/TO00 P13/TOH1/INTP6
Port 1 is an I/O port with an output latch. Port 1 can be set to the input mode or output mode in 1-bit units using
port mode register 1 (PM1). When the P10 to P13 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 1 (PU1).
This port can also be used for external interrupt request input, serial interface data I/O, and timer I/O.
Reset signal generation sets port 1 to input mode.
Figures 4-3 to 4-5 show block diagrams of port 1.
Cautions
To use P10/TxD6 as general-purpose port, clear bit 0 (TXDLV6) of asynchronous serial
interface control register 6 (ASICL6) to 0 (normal output of TxD6).