Datasheet
78K0/Ix2 CHAPTER 4 PORT FUNCTIONS
R01UH0010EJ0500 Rev.5.00 103
Feb 28, 2012
4.2.1 Port 0
78K0/IY2 78K0/IA2 78K0/IB2
16 Pins 20 Pins 30 Pins 32 Pins
P00/TI000/INTP0/TOH1/TI51 P00/TI000/INTP0 P00/TI000/INTP0/TOH1/TI51
P01/TO00/TI010
P02/SSI11/INTP5 P02/SSI11/INTP5
Remark Functions in angle brackets < > can be assigned by setting the input switch control register (MUXSEL).
Port 0 is an I/O port with an output latch. Port 0 can be set to the input mode or output mode in 1-bit units using port
mode register 0 (PM0). When the P00 to P02 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 0 (PU0).
This port can also be used for timer I/O, external interrupt request input, and serial interface chip select input.
The timer input or timer output can be assigned to P00 of the 78K0/IA2 and 78K0/IB2 (32 Pins) by setting the port
alternate switch control register (MUXSEL).
Reset signal generation sets port 0 to input mode.
Figures 4-1 to 4-3 show block diagrams of port 0.
Caution When using the 78K0/IB2 (32 pins), be sure to clear bit 1 of port mode register 0 (PM0) to 0 after the
reset status is released.
Figure 4-1. Block Diagram of P00 (1/2)
(1) 78K0/IA2, 78K0/IB2 (32 Pins)
P00/TI000/INTP0/<TOH1>/<TI51>
WR
PU
RD
PU0
PM0
WR
PM
PU00
TM5SEL1 TM5SEL0
Alternate function
(TI00, INTP0)
Alternate function
(TI51)
Alternate function
(TOH1)
PM00
V
DD
P-ch
MUXSEL
Output latch
(P00)
Internal bus
Selector
Selector
Selector
WR
PORT
P0
TMHSEL1
MUXSEL
TMHSEL0
Output signal to P34/TOH1
Input signal from P34/TI51
P0: Port register 0
PU0: Pull-up resistor option register 0
PM0: Port mode register 0
MUXSEL: Port alternate switch control register
RD: Read signal
WR: Write signal