UPD784938 Datasheet, PDF (187/733 Pages) NEC – 16-Bit Single-Chip Microcontrollers

CHAPTER 6 PORT FUNCTIONS
6.10.4 On-chip pull-up resistors
Port 9 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 PUOH9 bit of the pull-
up resistor option register H (PUOH) and the port 9 mode register (PM9).
When PUOH9 is 1, the on-chip pull-up resistors of the pins for which input is specified by the PM9 for port 9 (PM9n = 1, n
= 0 to 7) are enabled .
Figure 6-68. Pull-Up Resistor Option Register H (PUOH) Format
7
6
5
4
3
2
1
0 Address After reset R/W
PUOH 0
0
0
0
0 PUOH10 PUOH9 0 0FF4FH
00H
R/W
PUOH9 Port 9 Pull-Up Resistor Specification
0 Not used in port 9
1 Used in port 9
Remark When STOP mode is entered, setting PUOH to 00H is effective for reducing the current consumption.
Figure 6-69. Pull-Up Specification (Port 9)
VDD
Internal
bus
Input
buffer
(PUOH)
PUOH9
Port 9 mode register
(PM9)
Preliminary User’s Manual U13987EJ1V0UM00
P97
P96
P95
P91
P90
187