UPD784938 Datasheet, PDF (166/733 Pages) NEC – 16-Bit Single-Chip Microcontrollers

CHAPTER 6 PORT FUNCTIONS
6.7.4 On-chip pull-up resistors
Port 5 incorporates pull-up resistors. Use of these internal resistors when pull-up is necessary enables the number of parts
and the mounting area to be reduced.
Whether or not an on-chip pull-up resistor is to be used can be specified for each pin by setting the PUOL5 bit of the pull-
up resistor option register L (PUOL) and the port 5 mode register (PM5).
When PUOL5 is 1, the on-chip pull-up resistors of the pins for which input is specified by the PM5 for port 5 (PM5n = 1, n =
0 to 7) are enabled .
Figure 6-48. Pull-Up Resistor Option Register L (PUOL) Format
PUOL
7
6
5
4
3
2
1
0 Address After reset R/W
0 PUOL6 PUOL5 PUOL4 PUOL3 PUOL2 PUOL1 PUOL0 0FF4EH
00H
R/W
PUOL5 Port 5 Pull-Up Resistor Specification
0 Not used in port 5
1 Used in port 5
Caution When using the port 5 of the µPD784938 as an address bus, be sure to clear PUOL5 to 0 to disconnect the
on-chip pull-up resistor.
Remark When STOP mode is entered, setting PUOL to 00H is effective for reducing the current consumption.
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Preliminary User’s Manual U13987EJ1V0UM00