Renesas H8 Series Hardware Manual page 246

Section 8 I/O Ports
Port Pull-Up Control Register 3 (PUCR3)
Bit 7
PUCR3
Initial value 0
Read/Write R/W
PUCR3 controls whether the MOS pull-up of each of the port 3 pins P3
a PCR3 bit is cleared to 0, setting the corresponding PUCR3 bit to 1 turns on the MOS pull-up for
the corresponding pin, while clearing the bit to 0 turns off the MOS pull-up.
Upon reset, PUCR3 is initialized to H'00.
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 whether the PMOS transistor internal to pin P3
on or off. For the functions of the other bits, see the descriptions of port 1 (WDCKS and NCS) and
port 4 (IRQ0).
Bit 5—Pin P3 PMOS Transistor Control (POF1)
5
This bit selects whether the PMOS transistor of the output buffer for pin P3
Bit 5
POF1 Description
0 CMOS output
1 NMOS open-drain output
Note: The pin is an NMOS open-drain output when this bit is set to 1 and P3
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6 5
PUCR3 PUCR3
7 6
5
0 0
R/W R/W
6 5
— POF1
1 0
— R/W
pin functions.
0
4 3
PUCR3 PUCR3 PUCR3
4 3
0 0
R/W R/W
4 3
— — WDCKS
1 1
— —
2 1
PUCR3 PUCR3
1
2
0 0
R/W R/W R/W
to P3 is on or off. When
7 0
2 1
NCS
0 0
R/W R/W
is on or off.
5
(initial value)
is an output.
5
0
0
0
0
IRQ0
0
R/W
is on
5
is
5