Table of Contents
Advertisement
Section 8 I/O Ports
8.10.2
Register Descriptions
Table 8.16 summarizes the registers of port 9.
Table 8.16 Port 9 Registers
Address*
Name
H'EE008
Port 9 data direction register
H'FFFD8
Port 9 data register
Note: * Lower 20 bits of the address in advanced mode.
Port 9 Data Direction Register (P9DDR): P9DDR is an 8-bit write-only register that can select
input or output for each pin in port 9.
Bits 7 and 6 are reserved. They are fixed at 1, and cannot be modified.
Bit
7
Initial value
1
Read/Write
Reserved bits
When port 9 functions as an input/output port, a pin in port 9 becomes an output port if the
corresponding P9DDR bit is set to 1, and an input port if this bit is cleared to 0. For the method of
selecting the pin functions, see table 8.17.
P9DDR is a write-only register. Its value cannot be read. All bits return 1 when read.
P9DDR is initialized to H'C0 by a reset and in hardware standby mode. In software standby mode
it retains its previous setting. Therefore, if a transition is made to software standby mode while
port 9 is functioning as an input/output port and a P9DDR bit is set to 1, the corresponding pin
maintains its output state.
Rev. 4.00 Jan 26, 2006 page 302 of 938
REJ09B0276-0400
Abbreviation
P9DDR
P9DR
6
5
4
P9 DDR
P9 DDR
5
4
1
0
0
W
W
R/W
W
R/W
3
2
P9 DDR
P9 DDR
3
2
0
0
W
W
Port 9 data direction 5 to 0
These bits select input or
output for port 9 pins
Initial Value
H'C0
H'C0
1
0
P9 DDR
P9 DDR
1
0
0
0
W
W
Advertisement
Table of Contents
