UPD784938 Datasheet, PDF (123/733 Pages) NEC – 16-Bit Single-Chip Microcontrollers

CHAPTER 6 PORT FUNCTIONS
6.2.4 On-chip pull-up resistors
Port 0 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 means of the PUOL0 bit of the pull-
up resistor option register L (PUOL) and the port 0 mode register (PM0). When PUOL0 is 1, the on-chip pull-up resistors of the
pins for which input is specified by PM0 are enabled (PM0n = 1, n = 0 to 7).
Figure 6-6. 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
PUOL0 Port 0 Pull-Up Resistor Specification
0 Not used in port 0
1 Used in port 0
Remark When STOP mode is entered, setting PUOL to 00H is effective for reducing the current consumption.
Preliminary User’s Manual U13987EJ1V0UM00
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