3069RF-ZTAT Datasheet, PDF (304/1003 Pages) Renesas Technology Corp – RENESAS 16-BIT SINGLE-CHIP MICROCOMPUTER

Mode 7 (Single-Chip Mode): Port 8 is a generic input/output port. A pin in port 8 becomes an
output port if the corresponding P8DDR bit is set to 1, and an input port if this bit is cleared to 0.
P8DDR is a write-only register. Its value cannot be read. All bits return 1 when read.
P8DDR is initialized to H'F0 in modes 1 to 4, and to H'E0 in modes 5 and 7, by a reset and in
hardware standby mode. In software standby mode P8DDR retains its previous setting. Therefore,
if a transition is made to software standby mode while port 8 is functioning as an input/output port
and a P8DDR bit is set to 1, the corresponding pin maintains its output state.
Port 8 Data Register (P8DR): P8DR is an 8-bit readable/writable register that stores output data
for port 8. When port 8 functions as an output port, the value of this register is output. When a bit
in P8DDR is set to 1, if port 8 is read the value of the corresponding P8DR bit is returned. When
a bit in P8DDR is cleared to 0, if port 8 is read the corresponding pin logic level is read.
Bits 7 to 5 are reserved. They are fixed at 1, and cannot be modified.
Bit
Initial value
Read/Write
7
6
5
—
—
—
1
1
1
—
—
—
Reserved bits
4
P8 ₄
0
R/W
3
P8 ₃
0
R/W
2
P8 ₂
0
R/W
1
P8 ₁
0
R/W
Port 8 data 4 to 0
These bits store data
for port 8 pins
0
P8 ₀
0
R/W
P8DR is initialized to H'E0 by a reset and in hardware standby mode. In software standby mode it
retains its previous setting.
Rev. 5.0, 09/04, page 282 of 978