HD6413008VF25 Datasheet, PDF (191/688 Pages) Renesas Technology Corp – Old Company Name in Catalogs and Other Documents

7.2.2 Register Descriptions
Table 7.2 summarizes the registers of port 4.
Table 7.2 Port 4 Registers
Address*
Name
Abbreviation R/W
H'EE003
Port 4 data direction register
P4DDR
W
H'FFFD3
Port 4 data register
P4DR
R/W
H'EE03E
Port 4 input pull-up MOS control
P4PCR
R/W
register
Note: * Lower 20 bits of the address in advanced mode.
7. I/O Ports
Initial Value
H'00
H'00
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
When all areas are designated as 8-bit-access areas by the bus controller's bus width control
register (ABWCR), selecting 8-bit bus mode, port 4 functions as an input/output port. In this case,
a pin in port 4 becomes an output port if the corresponding P4DDR bit is set to 1, and an input
port if this bit is cleared to 0.
When at least one area is designated as a 16-bit-access area, selecting 16-bit bus mode, port 4
functions as part of the data bus, regardless of the P4DDR settings.
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. Therefore, if a transition is
made to software standby mode while port 4 is functioning as an input/output port and a P4DDR
bit is set to 1, the corresponding pin maintains its output state.
Rev.4.00 Aug. 20, 2007 Page 145 of 638
REJ09B0395-0400