Datasheet

Section 8 I/O Ports
Rev.7.00 Dec. 24, 2008 Page 223 of 698
REJ09B0074-0700
8.2 Port 3
The port 3 is a 4-bit I/O port also functioning as the SCI I/O pins and external interrupt input
(IRQ4) pins. The port 3 of the H8S/2218 Group has the same function as that of the H8S/2212
Group. The port 3 has the following registers.
• Port 3 data direction register (P3DDR)
• Port 3 data register (P3DR)
• Port 3 register (PORT3)
• Port 3 open-drain control register (P3ODR)
8.2.1 Port 3 Data Direction Register (P3DDR)
P3DDR specifies input or output for the pins of the port 3.
Since P3DDR is a write-only register, the bit manipulation instructions must not be used to write
P3DDR. For details, see section 2.9.4, Accessing Registers Containing Write-Only Bits.
Bit Bit Name Initial Value R/W Description
7 ⎯ Undefined ⎯ Reserved
This bit is undefined and cannot be modified.
6 P36DDR 0 W Setting a P3DDR bit to 1 makes the corresponding port 3
pin an output pin, while clearing the bit to 0 makes the pin
an input pin.
5 to
3
⎯ Undefined ⎯ Reserved
These bits are undefined and cannot be modified.
2
1
0
P32DDR
P31DDR
P30DDR
0
0
0
W
W
W
Setting a P3DDR bit to 1 makes the corresponding port 3
pin an output pin, while clearing the bit to 0 makes the pin
an input pin.