NEC 78K0 User Manual page 95

(3) Pull-up resistor option registers (PU0, PU1, PU3, PU7, and PU12)
These registers specify whether the on-chip pull-up resistors of P00, P01, P10 to P17, P30 to P33, P70 to P73, or
P120 are to be used or not. On-chip pull-up resistors can be used in 1-bit units only for the bits set to input mode
of the pins to which the use of an on-chip pull-up resistor has been specified in PU0, PU1, PU3, PU7, and PU12.
On-chip pull-up resistors cannot be connected for bits set to output mode and bits used as alternate-function
output pins, regardless of the settings of PU0, PU1, PU3, PU7, and PU12.
These registers can be set by a 1-bit or 8-bit memory manipulation instruction.
RESET input clears these registers to 00H.
Caution Use of a pull-up resistor can be specified for P60 to P63 pins by a mask option only in the mask
ROM versions.
Symbol 7 6
PU0 0 0
7 6
PU1
PU17 PU16
7 6
PU3
0 0
7 6
PU7 0 0
7 6
PU12
0 0
PUmn
0 On-chip pull-up resistor not connected
1 On-chip pull-up resistor connected
CHAPTER 4 PORT FUNCTIONS
Figure 4-18. Format of Pull-up Resistor Option Register
5 4 3
0 0 0
5 4 3
PU15 PU14 PU13
5 4 3
0 0 PU33
5 4 3
0 0 PU73
5 4 3
0 0 0
Pmn pin on-chip pull-up resistor selection
(m = 0, 1, 3, 7, 12; n = 0 to 7)
User's Manual U16227EJ2V0UD
2 1 0
0 PU01 PU00
2 1 0
PU12 PU11 PU10
2 1 0
PU32 PU31 PU30
2 1 0
PU72 PU71 PU70
2 1 0
0 0 PU120
Address After reset R/W
FF30H 00H R/W
FF31H 00H R/W
FF33H 00H R/W
FF37H 00H R/W
FF3CH 00H R/W
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