CHAPTER 4 PORT FUNCTIONS
User’s Manual U16898EJ3V0UD
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(4) Pull-up resistor option registers (PU2, PU3, PU4, PU12)
These registers are used to specify whether an on-chip pull-up resistor is connected to P20 to P23, P30, P31,
P40 to P45, and P123. By setting PU2, PU3, PU4, or PU12, an on-chip pull-up resistor can be connected to
the port pin corresponding to the bit of PU2, PU3, PU4, or PU12.
PU2, PU3, PU4, and PU12 are set by using a 1-bit or 8-bit memory manipulation instruction.
Reset signal generation set these registers to 00H.
Figure 4-16. Format of Pull-up Resistor Option Register
Address: FF32H After reset: 00H R/W
Symbol
7 6 5 4 3 2 1 0
PU2
0 0 0 0
PU23
PU22
PU21
PU20
Address: FF33H After reset: 00H R/W
Symbol
7 6 5 4 3 2 1 0
PU3
0 0 0 0 0 0
PU31
PU30
Address: FF34H After reset: 00H R/W
Symbol
7 6 5 4 3 2 1 0
PU4 0
0 PU45 PU44 PU43 PU42 PU41 PU40
Address: FF3CH After reset: 00H R/W
Symbol
7 6 5 4 3 2 1 0
PU12
0 0 0 0
PU123
0 0 0
PUmn
Selection of connection of on-chip pull-up resistor of Pmn (m = 2, 3, 4, or 12; n = 0 to 5)
0
Does not connect on-chip pull-up resistor
1
Connects on-chip pull-up resistor