HD64F2145 Datasheet, PDF (207/829 Pages) Renesas Technology Corp – Hitachi 16-Bit Single-Chip Microcomputer

8.4 Port 3
Port 3 is an 8-bit I/O port. Port 3 pins also function as a bidirectional data bus, XBS bidirectional
data bus, and LPC input/output pins. Port 3 functions change according to the operating mode.
Port 3 has the following registers.
• Port 3 data direction register (P3DDR)
• Port 3 data register (P3DR)
• Port 3 pull-up MOS control register (P3PCR)
8.4.1 Port 3 Data Direction Register (P3DDR)
P3DDR specifies input or output for the pins of port 3 on a bit-by-bit basis.
Bit Bit Name Initial Value R/W
7
P37DDR 0
W
6
P36DDR 0
W
5
P35DDR 0
W
4
P34DDR 0
W
3
P33DDR 0
W
2
P32DDR 0
W
1
P31DDR 0
W
0
P30DDR 0
W
Description
Modes 1, 2, and 3 (EXPE = 1)
The input/output direction specified by P3DDR is
ignored, and pins automatically function as data I/O
pins.
Modes 2 and 3 (EXPE = 0)
The corresponding port 3 pins are output ports
when P3DDR bits are set to 1, and input ports when
cleared to 0.
8.4.2 Port 3 Data Register (P3DR)
P3DR stores output data of port 3.
Bit Bit Name Initial Value R/W
7
P37DR
0
R/W
6
P36DR
0
R/W
5
P35DR
0
R/W
4
P34DR
0
R/W
3
P33DR
0
R/W
2
P32DR
0
R/W
1
P31DR
0
R/W
0
P30DR
0
R/W
Description
If a port 3 read is performed while P3DDR bits are
set to 1, the P3DR values are read directly,
regardless of the actual pin states. If a port 3 read is
performed while P3DDR bits are cleared to 0, the
pin states are read.
Rev. 2.0, 08/02, page 167 of 788