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Section 8 I/O Ports
In modes 1 to 4, P1DDR bits are always read as 1, and cannot be modified.
In modes 5 to 7, P1DDR is a write-only register. Its value cannot be read. All bits return 1 when
read.
P1DDR is initialized to H'FF in modes 1 to 4, and to H'00 in modes 5 to 7, 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 1 is functioning as an input/output port and
a P1DDR bit is set to 1, the corresponding pin maintains its output state.
Port 1 Data Register (P1DR): P1DR is an 8-bit readable/writable register that stores port 1
output data. When port 1 functions as an output port, the value of this register is output. When this
register is read, the pin logic level is read for bits for which the P1DDR setting is 0, and the P1DR
value is read for bits for which the P1DDR setting is 1.
Bit
7
P1
Initial value
0
Read/Write
R/W
P1DR is initialized to H'00 by a reset and in hardware standby mode. In software standby mode it
retains its previous setting.
Rev. 4.00 Jan 26, 2006 page 274 of 938
REJ09B0276-0400
6
5
P1
P1
7
6
5
0
0
R/W
R/W
Port 1 data 7 to 0
These bits store data for port 1 pins
4
3
2
P1
P1
P1
4
3
0
0
0
R/W
R/W
R/W
1
0
P1
P1
2
1
0
0
0
R/W
R/W
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