CHAPTER 4 PORT FUNCTIONS
(7) Pull-up resistor option register B9 (PUB9)Note
Pull-up resistor option register B9 (PUB9) sets whether on-chip pull-up resistors on P90 to P97 are used or
not. On the port specified to use an on-chip pull-up resistor by PUB9, the pull-up resistor can be internally
used only for bits set in the input mode. No on-chip pull-up resistors can be used for the bits set in the output
mode regardless of the setting of PUB9. This also applies to when the pins are used for alternate function.
PUB9 is set with a 1-bit or 8-bit memory manipulation instruction.
RESET input sets PUB9 to 00H.
Note Incorporated only in the µPD789426 and 789436 Subseries.
Figure 4-24. Format of Pull-Up Resistor Option Register B9
Symbol
PUB9 PUB97 PUB96 PUB95 PUB94 PUB93 PUB92 PUB91 PUB90
<7> <6> <5> <4> <3> <2> <1> <0>
Address
FF39H
After reset
00H
R/W
R/W
PUB9n
P9n on-chip pull-up resistor selection
(n = 0 to 7)
On-chip pull-up resistor not used
On-chip pull-up resistor used
0
1
User’s Manual U15075EJ1V0UM00
101
NEC [ NEC ]
