Datasheet

78K0/Ix2 CHAPTER 4 PORT FUNCTIONS
R01UH0010EJ0500 Rev.5.00 138
Feb 28, 2012
(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 (sets only PU12 to 20H).
Figure 4-31. Format of Pull-up Resistor Option Register (78K0/IY2)
7
0
Symbol
PU3
6
0
5
0
4
PU34
3
PU33
2
PU32
1
PU31
0
0
Address
FF33H
After reset
00H
R/W
R/W
0
PU12
0 PU125 0 0 0 0 0
FF3CH 20H R/W
PUmn
Pmn pin on-chip pull-up resistor selection
(m = 3, 12; n = 1 to 5)
0 On-chip pull-up resistor not connected
1 On-chip pull-up resistor connected