Table of Contents
Advertisement
(2) Pull-up resistor option register (PUO)
This register is used to set whether to use an on-chip pull-up resistor at each port or not. An on-chip pull-up resistor
is internally used only for the bits that are set to the input mode at a port where pull-up resistor use has been
specified with PUO. 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 PUO setting.
PUO is set with a 1-bit or 8-bit memory manipulation instruction.
RESET input sets this register to 00H.
Cautions 1. P00 and P04 pins do not incorporate a pull-up resistor.
Symbol
PUO
www.DataSheet4U.com
2. When port 1, port 4, port 5, or P64 to P67 is used as an alternate function pin, an on-chip pull-
up resistor cannot be connected even if 1 is set in PUOm (m = 1, 4 to 6).
3. For P60 to P63 pins, only mask ROM versions can contain pull-up resistors by mask option.
Figure 6-17. Pull-Up Resistor Option Register Format
7
<6>
<5>
<4>
0
PUO6 PUO5 PUO4
PUO3
CHAPTER 6 PORT FUNCTIONS
<3>
<2>
<1>
<0>
PUO2
PUO1
PUO0
Address
When Reset
R/W
FFF7H
00H
R/W
PUOm
Pm On-chip Pull-up Resistor
(m = 0, 1, 2, 3, 4, 5, 6)
0
On-chip pull-up resistor not used
1
On-chip pull-up resistor used
149
Advertisement
Table of Contents
