HD6413002 Datasheet, PDF (257/700 Pages) Renesas Technology Corp – High-performance single-chip microcontroller

9.2.2 Register Descriptions
Table 9-2 summarizes the registers of port 4.
Table 9-2 Port 4 Registers
Address*
Name
H'FFC5
Port 4 data direction register
H'FFC7
Port 4 data register
H'FFDA
Port 4 input pull-up control register
Note: * Lower 16 bits of the address.
Abbreviation
P4DDR
P4DR
P4PCR
R/W Initial Value
W
H'00
R/W H'00
R/W H'00
Port 4 Data Direction Register (P4DDR): P4DDR is an 8-bit write-only register that can select
input or output for each pin in port 4.
Bit
Initial value
Read/Write
7
6
5
4
3
2
1
0
P4₇DDR P4₆DDR P4₅DDR P4₄DDR P4₃DDR P4₂DDR P4₁DDR P4₀DDR
0
0
0
0
0
0
0
0
W
W
W
W
W
W
W
W
Port 4 data direction 7 to 0
These bits select input or output for port 4 pins
8-Bit Bus Mode: When all areas are designated as 8-bit-access areas, selecting 8-bit bus mode,
port 4 functions as a generic input/output port. A pin in port 4 becomes an output pin if the
corresponding P4DDR bit is set to 1, and an input pin if this bit is cleared to 0.
16-Bit Bus Mode: When at least one area is designated as a 16-bit-access area, selecting 16-bit
bus mode, port 4 functions as the lower data bus.
P4DDR is a write-only register. Its value cannot be read. All bits return 1 when read.
P4DDR is initialized to H'00 by a reset and in hardware standby mode. In software standby mode
it retains its previous setting.
ABWCR and P4DDR are not initialized in software standby mode. When port 4 functions as a
generic input/output port, if a P4DDR bit is set to 1, the corresponding pin maintains its output
state in software standby mode.
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