CHAPTER 4 PORT FUNCTIONS
Preliminary User’s Manual U16846EJ1V0UD
69
4.2.2 Port 1
Port 1 is an 8-bit 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 P17 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, clock I/O, and timer I/O, and
flash memory programming mode setting.
RESET input sets port 1 to input mode.
Figures 4-5 to 4-9 show block diagrams of port 1.
Caution When using P10/SCK10 (/TxD0
Note
), P11/SI10 (/RxD0
Note
), and P12/SO10 as general-purpose ports,
do not write to serial clock selection register 10 (CSIC10).
Figure 4-5. Block Diagram of P10
P10/SCK10 (/TxD0
Note
)
WR
PU
RD
WR
PORT
WR
PM
PU10
Alternate
function
Output latch
(P10)
PM10
PU1
PM1
Alternate
function
V
DD
P-ch
Selector
Internal bus
Note Available only in the
µ
PD78F0102H and 78F0103H.
PU1:
Pull-up resistor option register 1
PM1:
Port mode register 1
RD: Read
signal
WR
××
: Write
signal