
CHAPTER 4 PORT FUNCTIONS
User’s Manual U15905EJ2V1UD
135
(f) Pull-up resistor option register 9 (PU9)
This is a 16-bit register that specifies connection of an internal pull-up resistor.
This register can be read or written only in 16-bit units.
If the higher 8 bits of the PU9 register are used as PU9H and the lower 8 bits as PU9L, however, PU9H
and PU9L can be manipulated in 8-bit or 1-bit units.
Not connected
Connected
PU9n
0
1
Controls connection of internal pull-up resistor (n = 0 to 15)
PU9 (PU9HNote)
(PU9L)
After reset: 0000H
R/W
Address: PU9 FFFFFC52H,
PU9L FFFFFC52H, PU9H FFFFFC53H
PU97
PU96
PU95
PU94
PU93
PU92
PU91
PU90
PU915
PU914
PU913
PU912
PU911
PU910
PU99
PU98
8
9
10
11
12
13
14
15
Note
When reading or writing bits 8 to 15 of the PU9 register in 8-bit or 1-bit units, specify these bits as bits 0
to 7 of the PU9H register.
(g) External interrupt falling edge specification register 9 (INTF9)
This 16-bit register specifies detection of the falling edge of the external interrupt pins.
It can be read or written only in 16-bit units. If the higher 8 bits of the INTF9 register are used as INTF9H
and the lower 8 bits as INTF9L, however, INTF9H and INTF9L can be manipulated in 8-bit or 1-bit units.
Caution
Set the port mode after clearing the INTF9n and INTR9n bits to 0 when switching from the
external interrupt function (alternate function) to the port function because an edge may
be detected.
INTF9
(INTF9L)
After reset: 0000H
R/W
Address: INTF9 FFFFFC12H, INTF9L FFFFFC12H
0
INTF93
INTF92
0
00
0
8
9
10
11
12
13
14
15
Remark
For how to specify a valid edge, refer to Table 4-11.