Datasheet

Section 10 I/O Ports
Rev.7.00 Mar. 18, 2009 page 525 of 1136
REJ09B0109-0700
10.13 Port E
Port E is an 8-bit I/O port that also has other functions. The port E has the following registers.
• Port E data direction register (PEDDR)
• Port E data register (PEDR)
• Port E register (PORTE)
• Port E pull-up MOS control register (PEPCR)
10.13.1 Port E Data Direction Register (PEDDR)
The individual bits of PEDDR specify input or output for the pins of port E.
PEDDR cannot be read; if it is, an undefined value will be read.
Bit Bit Name Initial Value R/W Description
7 PE7DDR 0 W
6 PE6DDR 0 W
5 PE5DDR 0 W
4 PE4DDR 0 W
3 PE3DDR 0 W
2 PE2DDR 0 W
1 PE1DDR 0 W
0 PE0DDR 0 W
• Modes 1, 2, and 4
When 8-bit bus mode is selected, port E
functions as an I/O port. The pin states can be
changed with PEDDR.
When 16-bit bus mode is selected, port E is
designated for data input/output.
For details on 8-bit and 16-bit bus modes, see
section 6, Bus Controller (BSC).
• Mode 7 (when EXPE = 1)
When 8-bit bus mode is selected, port E
functions as an I/O port. Setting a PEDDR bit to 1
makes the corresponding port E pin an output
port, while clearing the bit to 0 makes the pin an
input port.
When 16-bit bus mode is selected, port E is
designated for data input/output.
• Mode 7 (when EXPE = 0)
Port E is an I/O port, and its pin functions can be
switched with PEDDR.