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CHAPTER 4 PORT FUNCTIONS
User’s Manual U19780EJ2V0UD
117
(3) Pull-up resistor option registers (PUxx)
These registers specify whether the on-chip pull-up resistors 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 these registers. On-chip pull-up resistors cannot be connected to bits set to output mode
and bits used as alternate-function output pins, regardless of the settings of these registers.
These registers can be set by a 1-bit or 8-bit memory manipulation instruction.
Reset signal generation clears these registers to 00H.
Figure 4-27. Format of Pull-up Resistor Option Register (1/2)
(1) 78K0/KB2-A
Symbol
7 6 5 4 3 2 1 0
Address
After
reset
R/W
PU1
0 0 0 0
PU13
PU12
PU11
PU10
FF31H
00H
R/W
PU3 0
0 PU35 0
0 PU32
PU31 0 FF33H 00H R/W
PU12
0 0 0 0 0 0 0
PU120
FF3CH
00H
R/W
PUmn
Pmn pin on-chip pull-up resistor selection
(m = 1, 3, 12 ; n = 0 to 3, 5)
0
On-chip pull-up resistor not connected
1
On-chip pull-up resistor connected