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CHAPTER 6 PORT FUNCTIONS
PUO7 PUO6 PUO5 PUO4 PUO2 PUO1 PUO0PUOL
PUOm
Pm Internal Pull-up Resistor Selection
(m=0 to 7, 12, 13)
0
1
Internal pull-up resistor not used
Internal pull-up resistor used
FFF7H 00H R/W
<7> <6> <5> <4>
PUO3
<3> <2> <0>
<1>
00
PUO13PUO12 0
00PUOH FFF3H 00H R/W
7 6 <5> <4>Symbol
Address
After
Reset
R/W
0
76 32 0
1
(2) Pull-up resistor option register (PUOH, PUOL)
This register is used to set whether to use an internal pull-up resistor at each port or not. A pull-up resistor
is internally used at bits which are set to the input mode at a port where on-chip pull-up resistor use has been
specified with PUOH, PUOL. No on-chip pull-up resistors can be used to the bits set to the output mode or
to the bits used as an analog input pin, irrespective of PUOH or PUOL setting.
PUOH and PUOL are set with a 1-bit or 8-bit memory manipulation instruction.
RESET input sets this register to 00H.
Cautions 1. P00 and P07 pins do not incorporate a pull-up resistor.
2. When ports 1, 4, 5, and P64 to P67 pins are used as dual-function pins, an on-chip pull-
up resistor cannot be used even if 1 is set in PUOm bit of PUOH, PUOL (m = 1, 4 to 6).
3. Pins P60 to P63 can be connected with pull-up resistor by mask option only for mask
ROM version.
Figure 6-20. Pull-Up Resistor Option Register Format
Caution Bits 0 to 3, 6, and 7 of PUOH should be set to 0.