158
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
1
and
IRQ
0
. Table 7-12 describes the selection of pin
functions.
Table 7-12 Port 8 Pin Functions
Pin
Pin Functions and Selection Method
P8
1
/
IRQ
1
Bit P8
1
DDR selects the pin function as follows
P8
1
DDR
0
1
Modes 1, 3, 5, and 6
Mode 7
Pin function
P8
1
input
Illegal setting
P8
1
output
IRQ
1
input
P8
0
/
IRQ
0
Bit P8
0
DDR selects the pin function as follows
P8
0
DDR
0
1
Pin function
P8
0
input
P8
0
output
IRQ
0
input