UPD784938 Datasheet, PDF (141/733 Pages) NEC – 16-Bit Single-Chip Microcontrollers

CHAPTER 6 PORT FUNCTIONS
6.4.2 Input mode/control mode setting
Port 2 is an input-only port, and there is no register for setting the input mode.
Also, control signal input is always possible, and therefore the signal to be used is determined by the control registers for
individual on-chip hardware items.
6.4.3 Operating status
Port 2 is an input-only port, and pin levels can always be read or tested.
Figure 6-23. Port Specified as Input Port
Internal
bus
RDIN
P2n
n = 0 to 7
6.4.4 On-chip pull-up resistors
P22 to P27 incorporate 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 all six pins, P22 to P27, together by means of
the PUOL2 bit of the pull-up resistor option register L (PUOL) (bit-wise specification is not possible).
P20 and P21 do not incorporate a pull-up resistor.
Figure 6-24. 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
PUOL2 Port 2 Pull-Up Resistor Specification
0 Not used in port 2
1 Used in pins P22 to P27
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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