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RL78/G1A CHAPTER 4 PORT FUNCTIONS
R01UH0305EJ0200 Rev.2.00 107
Jul 04, 2013
4.3.3 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 both normal output mode (POMmn = 0) and input mode (PMmn = 1) for 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 and analog setting (PMC = 1, ADPC =
1), 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 (Only PU4 is set to 01H).
Caution When a port with the PIMn register is input from different potential device to the TTL buffer, pull up to
the power supply of the different potential device via an external resistor by setting PUmn = 0.
Figure 4-3. Format of Pull-up Resistor Option Register
Symbol 7 6 5 4 3 2 1 0 Address After reset R/W
PU0 0 PU06 PU05 PU04 PU03 PU02 PU01 PU00 F0030H 00H R/W
PU1 0 PU16 PU15 PU14 PU13 PU12 PU11 PU10 F0031H 00H R/W
PU3 0 0 0 0 0 0 PU31 PU30 F0033H 00H R/W
PU4 0 0 0 0 PU43 PU42 PU41 PU40 F0034H 01H R/W
PU5 0 0 0 0 0 0 PU51 PU50 F0035H 00H R/W
PU7 PU77 PU76 PU75 PU74 PU73 PU72 PU71 PU70 F0037H 00H R/W
PU12 0 0 0 0 0 0 0 PU120 F003CH 00H R/W
PU14 0 0 0 0 0 0 PU141 PU140 F003EH 00H R/W
PUmn
Pmn pin on-chip pull-up resistor selection
(m = 0, 1, 3 to 5 , 7, 12, 14; n = 0 to 7)
0 On-chip pull-up resistor not connected
1 On-chip pull-up resistor connected
Caution Be sure to set bits that are not mounted to their initial values.
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