93
CHAPTER 4 PORT FUNCTIONS
User’s Manual U15798EJ2V0UD
4.2.3 Port 2
Port 2 is an 8-bit I/O port with an output latch. The P20 to P27 pins can be set to input mode/output mode in 1-
bit units using port mode register 2 (PM2). An on-chip pull-up resistor can be used for the P20 to P27 pins in 1-bit
units using pull-up resistor option register 2 (PU2).
This port can also be used for serial interface data I/O and clock I/O.
RESET input sets port 2 to input mode.
Figures 4-5 to 4-7 show block diagrams of port 2.
Caution When P23/SI1, P24/SO1, and P25/SCK1 are used as general-purpose ports, do not write to the
serial clock select register (CSIC1).
Figure 4-5. Block Diagram of P20, P23, P26
PU: Pull-up resistor option register
PM: Port mode register
RD: Port 2 read signal
WR: Port 2 write signal
Internal bus
V
DD0
P-ch
P20/SI3,
P23/SI1,
P26/RxD0
WR
PU
RD
WR
PORT
WR
PM
PU20, PU23,
PU26
Alternate
function
Output latch
(P20, P23, P26)
PM20, PM23,
PM26
Selector
Содержание mPD780344 Series
Страница 2: ...2 User s Manual U15798EJ2V0UD MEMO...