Renesas H8 Series Hardware Manual page 252

Section 8 I/O Ports
Port Control Register 4 (PCR4)
Bit 7

Initial value 1

Read/Write
PCR4 is an 8-bit register for controlling whether each of port 4 pins P4
input pin or output pin. Setting a PCR4 bit to 1 makes the corresponding pin an output pin, while
clearing the bit to 0 makes the pin an input pin. PCR4 and PDR4 settings are valid when the
corresponding pins are designated for general-purpose input/output by SCR3.
Upon reset, PCR4 is initialized to H'F8.
PCR4 is a write-only register, which is always read as all 1s.
Port Mode Register 2 (PMR2)
Bit 7

Initial value 1

Read/Write
PMR2 is an 8-bit read/write register. It controls whether the PMOS transistor internal to P3
or off, the selection of the watchdog timer clock, the selection of TMIG noise cancellation, and
switching of the P4 /
3
I R Q
Upon reset, PMR2 is initialized to H'D8.
This section only deals with the bit that controls switching of the P4
functions of the other bits, see the descriptions of port 1 (WDCKS and NCS) and port 3 (POF1).
Bit 0—P4 / Pin Function Switch (IRQ
3 0
I R Q
This bit selects whether pin P4
Bit 0
IRQ Description
0
0 Functions as P4
1 Functions as
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REJ09B0042-0700
6 5
 
1 1
 
6 5

POF1
1 0

R/W
pin functions.
0
)
0
/ is used as P4
3 0
I R Q
input pin
3
input pin
0
I R Q
4 3 2
 
PCR4
1 1 0
 
W
2
4 3 2
 
WDCKS
1 1 0
 
R/W
/
3
I R Q
or as .
3 0
I R Q
1 0
PCR4 PCR4
2 1
0 0
W W
to P4 functions as an
0
1 0
NCS IRQ
0
0 0
R/W R/W
is on
5
pin functions. For the
0
(initial value)
0