Pin Functions; Pin States - Hitachi H8/3937 Series Hardware Manual

2. Port control register 8 (PCR8)
Bit 7
PCR8
Initial value 0
Read/Write W
PCR8 is an 8-bit register for controlling whether each of the port 8 pins P8
input or output pin. Setting a PCR8 bit to 1 makes the corresponding pin an output pin, while
clearing the bit to 0 makes the pin an input pin.
Upon reset, PCR8 is initialized to H'00.
PCR8 is a write-only register, which is always read as all 1s.
8.9.3

Pin Functions

Table 8-24 shows the port 8 pin functions.
Table 8-24 Port 8 Pin Functions
Pin Pin Functions and Selection Method
P8 to P8 The pin function depends on bit PCR8
7 0
8.9.4

Pin States

Table 8-25 shows the port 8 pin states in each operating mode.
Table 8-25 Port 8 Pin States
Pins Reset
P8 to P8 High-
7 0
impedance
6 5
PCR8 PCR8
7 6 5
0 0
W W
PCR8
n
Pin function
Sleep Subsleep
Retains Retains
previous previous
state state
4 3
PCR8 PCR8 PCR8
4 3
0 0
W W
in PCR8.
n
0
P8 input pin
n
Standby Watch
High- Retains
impedance previous
state
2 1 0
PCR8 PCR8
2 1
0 0 0
W W W
to P8 functions as an
7 0
(n = 7 to 0)
1
P8 output pin
n
Subactive Active
Functional Functional
0
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