Pull-Up Resistor Option Register Format - NEC PD78076 User Manual

(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, or port 8 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 and
PUOL (m = 1, 4 to 6, or 8).
3. Pins P60 to P63 and P90 to P93 can be incorporated with pull-up resistor by mask option
only for mask ROM version.
Symbol 7 6 6
PUOH 0 0 PUO13 PUO12
<7> <6> 6
PUOL PUO7 PUO6 PUO5 PUO4
Caution Bits 3, 6, and 7 of PUOH should be set to 0.
160
CHAPTER 6 PORT FUNCTIONS
Figure 6-25. Pull-Up Resistor Option Register Format
<5> <4> 3 <2> <1>
0 PUO10 PUO9 PUO8
<5> <4> <3> <2> <1>
PUO3 PUO2 PUO1 PUO0
After
<0> Address Reset
FFF3H 00H
<0>
FFF7H 00H
Pm Internal Pull-up Resistor Selection
PUOm
(m = 0 to 10, 12, 13)
0 Internal pull-up resistor not used
1 Internal pull-up resistor used
R/W
R/W
R/W