Registers Of Port 4 (Pdr4) - Fujitsu F2MC-8L F202RA Hardware Manual

CHAPTER 4 I/O PORTS
4.4.1

Registers of Port 4 (PDR4)

This section describes the registers associated with port 4.
■ Functions of Port 4 Registers
● Port 4 data register (PDR4)
The PDR4 register indicates the state of the pins. For a pin set to function as an output port, the same value
("0"or "1") as held by the output latch can be read from this register. If the pin is set to function as an input
port, however, its output latch value cannot be read from the register.
Note:
When a bit manipulation instruction (SETB, CLRB) is executed, the output latch values, not the value
states of the pins, are read; thus, output latch values, excepting those for bits to be manipulated, do not
change.
Table 4.4-3 lists the functions of the port 4 registers.
Table 4.4-3 Functions of Port 4 Registers
Register
Data
name
0
Port 4
data
register
Pin state
(PDR4)
1 is "H"
level.
Port 4
0
data
direction
register
1
(DDR4)
Port 4
0 N-ch open-drain type
output
format
setting
1 CMOS push-pull type
register
(OUT4)
R/W : Readable and Writable
X : Undefined
92
When being read
Pin state is "L" level.
N-ch open-
drain type
CMOS
push-pull
type
Input port pin
Output port pin
When being written
Output latch of "0" is set and
"L" level is output to the pin
in output port mode.
Output latch of "1" is set and
the pin in output port mode
is set at Hi-Z.
Output latch of "1" is set and
"H" level is output to the pin
in output port mode.
The pin is set to function as
input pin with output
transistor operation disabled.
The pin is set to function as
output pin with output
transistor operation enabled.
Output format of the pin is
set to N-ch open-drain type.
Output format of the pin is
set to CMOS push-pull type.
Read/
Address
Write
R/W 000F ----XXXX
H
R/W 0010 ----0000
H
R/W 0011 ----0000
H
Initial
value
B
B
B