uPD789871 Subseries 8-Bit Single-Chip Microcontrollers PUM
uPD789871 Subseries 8-Bit Single-Chip Microcontrollers PUM
uPD789871 Subseries 8-Bit Single-Chip Microcontrollers PUM
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2.2 Description of Pin Functions<br />
26<br />
CHAPTER 2 PIN FUNCTIONS<br />
2.2.1 P00 to P07 (Port 0)<br />
These pins constitute an 8-bit I/O port and can be set in input or output port mode in 1-bit units by using port mode<br />
register 0 (PM0). When used as an input port, use of an on-chip pull-up resistor can be specified by pull-up resistor<br />
option register 0 (PU0) in port units.<br />
2.2.2 P10 to P12 (Port 1)<br />
These pins constitute a 3-bit I/O port and can be set in input or output port mode in 1-bit units by port mode register<br />
1 (PM1). When used as an input port, use of an on-chip pull-up resistor can be specified by pull-up resistor option<br />
register 0 (PU0) in port units.<br />
2.2.3 P20 to P25 (Port 2)<br />
These pins constitute a 6-bit I/O port. In addition, these pins enable timer input serial interface data I/O, and external<br />
interrupt input.<br />
Port 2 can be specified in the following operation modes in 1-bit units.<br />
(1) Port mode<br />
In this mode, port 2 functions as a 6-bit I/O port. Port 2 can be set in the input or output mode in 1-bit units<br />
by port mode register 2 (PM2). When used as an input port, use of an on-chip pull-up resist can be specified<br />
by pull-up resistor option register B2 (PUB2) in 1-bit units.<br />
(2) Control mode<br />
In this mode, P20 to P25 function as the timer input, serial interface data I/O, and external interrupt input.<br />
(a) TI<br />
This is the timer input pin of 8-bit remote control timer.<br />
(b) SI10, SO10<br />
These are the serial data I/O pins of the serial interface.<br />
(c) SCK10<br />
This is the serial clock I/O pin of the serial interface.<br />
(d) INTP0, INTP1<br />
These are the external interrupt input pins for which the valid edge (rising edge, falling edge, or both rising<br />
and falling edges) can be specified.<br />
2.2.4 P80 to P87 (Port 8)<br />
These pins constitute an 8-bit P-ch open-drain I/O port. In addition, they also function as VFD controller/driver<br />
outputs. Port 8 can be specified in the following operation mode in 1-bit units.<br />
(1) Port mode<br />
In this mode, port 8 functions as an 8-bit P-ch open-drain I/O Port. Port 8 can be set in the input or output<br />
port mode in 1-bit units by port mode register 8 (PM8).<br />
(2) Control mode<br />
In this mode, these pins function as VFD controller/driver outputs (FIP17 to FIP24). For mask ROM versions,<br />
use of a pull-down resistor for VLOAD can be specified by a mask option.<br />
Preliminary User’s Manual U14938EJ1V0UM
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