NEC PD78P214 Manuale Utente
65
Chapter 5 Port Functions
5
Fig. 5-7 Port Specified as an Input Port
Caution For the in-circuit emulator, the level of each port 2 pin from which noise has not been removed can be read and tested.
5.3.4 Built-In Pull-Up Resistor
P22 through P27 have built-in pull-up resistors. When they must be pulled up, the built-in pull-up resistors should
be used. Use of the built-in pull-up resistors can reduce the number of the required components and the required
installation space.
be used. Use of the built-in pull-up resistors can reduce the number of the required components and the required
installation space.
The PUO2 bit of the pull-up-resistor-option register (PUO) can specify whether to use the built-in pull-up resistors
at P22 through P27, for all six pins at one time. (It is impossible to specify use of the built-in pull-up resistor for
an individual bit independently of the other bits.)
at P22 through P27, for all six pins at one time. (It is impossible to specify use of the built-in pull-up resistor for
an individual bit independently of the other bits.)
P20 or P21 does not have a built-in pull-up resistor.
Fig. 5-8 Built-In Pull-Up Resistor Format
0
7
PUO6
6
PUO5
5
PUO4
4
PUO3
3
PUO2
2
0
1
0
0
PUO
PUO2
Connected with pins P22 to P27
Not connected with port 2
Specifies pull-up resistor connection of port 2
(00H when RESET is input)
0
1
Remark Resetting the PUO2 bit to 00H can reduce the required current in the STOP mode.
Internal bus
RD
IN
Noise
eliminator
P2n
n = 0 to 7
n = 0 to 7