Hitachi F-ZTAT H8/3039 Series Hardware Manual page 172

Bits 7 to 2 are reserved. Bits 7 to 5 cannot be modified and always read 1. Bit 4, 3, and 2 can be
written and read, but it cannot be used for port input or output. If bit 4, 3, and 2 of P8DDR is read
while its value is 1, bit 4, 3 and 2 of P8DR is read directly. If bit 4, 3, and 2 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
functions.
Table 7-12 Port 8 Pin Functions
Pin Pin Functions and Selection Method
P8 /IRQ Bit P8
1 1 1
P8 DDR
1
Pin function
P8 /IRQ Bit P8
0 0 0
P8 DDR
0
Pin function
and IRQ
1
DDR selects the pin function as follows
0
P8 input
1
DDR selects the pin function as follows
. Table 7-12 describes the selection of pin
0
Modes 1, 3, and 5
Illegal setting
IRQ
0
P8 input
0
IRQ
1
Modes 6 and 7
P8
input
1
1
P8 output
0
input
0
output
1
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