CHAPTER 4 PORT FUNCTIONS
User’s Manual U18172EJ2V0UD
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(4) Pull-up resistor option registers (PU2 to PU4)
These registers are used to specify whether an on-chip pull-up resistor is connected to P20 to P23, P32, P40
and P43. By setting PU2 to PU4, an on-chip pull-up resistor can be connected to the port pin corresponding to
the bit of PU2 to PU4.
PU2 to PU4 are set by using a 1-bit or 8-bit memory manipulation instruction.
Reset signal generation set these registers to 00H.
Figure 4-11. 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
PU32
0 0
Address: FF34H, After reset: 00H R/W
Symbol
7 6 5 4 3 2 1 0
PU4
0 0 0 0
PU43
0 0
PU40
PUmn
Selection of connection of on-chip pull-up resistor of Pmn (m = 2 to 4; n = 0 to 3)
0
Does not connect on-chip pull-up resistor
1
Connects on-chip pull-up resistor