CHAPTER 4 PORT FUNCTIONS
(5) Pull-up resistor option register B7 (PUB7)
Pull-up resistor option register B7 (PUB7) sets whether on-chip pull-up resistors on P70 to P72 are used or
not. On the port specified to use an on-chip pull-up resistor by PUB7, 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 PUB7. This also applies to when the pins are used for alternate function.
PUB7 is set with a 1-bit or 8-bit memory manipulation instructions.
RESET input sets PUB7 to 00H.
Figure 4-22. Format of Pull-Up Resistor Option Register B7
Symbol
PUB7
7
0
6
0
5
0
4
0
3
0
<2> <1> <0>
Address
FF37H
After reset
00H
R/W
R/W
PUB72 PUB71 PUB70
PUB7n
P7n on-chip pull-up resistor selection
(n = 0 to 2)
On-chip pull-up resistor not used
On-chip pull-up resistor used
0
1
(6) Pull-up resistor option register B8 (PUB8)Note
Pull-up resistor option register B8 (PUB8) sets whether on-chip pull-up resistors on P80 and P81 are used or
not. On the port specified to use an on-chip pull-up resistor by PUB8, 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 PUB8. This also applies to when the pins are used for alternate functions.
PUB8 is set with a 1-bit or 8-bit memory manipulation instruction.
RESET input sets PUB8 to 00H.
Note Incorporated only in the µPD789426 and 789436 Subseries.
Figure 4-23. Format of Pull-Up Resistor Option Register B8
Symbol
PUB8
7
0
6
0
5
0
4
0
3
0
2
0
<1> <0>
Address
FF38H
After reset
00H
R/W
R/W
PUB81 PUB80
PUB8n
P8n on-chip pull-up resistor selection
(n = 0, 1)
On-chip pull-up resistor not used
On-chip pull-up resistor used
0
1
100
User’s Manual U15075EJ1V0UM00
NEC [ NEC ]
