HD643303x Hitachi, HD643303x Datasheet - Page 163

• Manufacturer Part Number: HD643303x
• Description: Hitachi Microcomputer
• Manufacturer: Hitachi

Port 8 Data Register (P8DR): P8DR is an 8-bit readable/writable register that stores data for pins
P8
When a bit in P8DDR is set to 1, if port 8 is read the value of the corresponding P8DR bit is
returned directly. When a bit in P8DDR is cleared to 0, if port 8 is read the corresponding pin level
is read.
Bits 7 to 4 are reserved. Bits 7 to 5 cannot be modified and always read 1. Bit 4 can be written and
read, but it cannot be used for port input or output. If bit 4 of P8DDR is read while its value is 1, bit
4 of P8DR is read directly. If bit 4 of P8DDR is read while its value is 0, it always reads 1.
P8DR is initialized to H'E0 by a reset and in hardware standby mode. In software standby mode it
retains its previous setting.
7.8.3 Pin Functions
The port 8 pins are also used for IRQ
Bit
Initial value
Read/Write
3
to P8
0
.
—
—
7
1
Reserved bits
—
—
6
1
3
to IRQ
—
—
5
1
0
. Table 7-12 describes the selection of pin functions.
148
R/W
—
4
0
R/W
P8
3
0
3
Port 8 data 4 to 0
These bits store data
for port 8 pins
R/W
P8
2
0
2
R/W
P8
1
0
1
R/W
P8
0
0
0