NEC PD78078 用户手册

156

CHAPTER 6 PORT FUNCTIONS

6.2.14 Port 13

This is a 2-bit input/output port with output latches. Input mode/output mode can be specified in 1-bit units with

the port mode register 13 (PM13). When pins P130 and P131 are used as input port pins, an on-chip pull-up resistor

can be connected in 2-bit units with a pull-up resistor option register H (PUOH).

These pins are dual function pin and serve as D/A converter analog outputs.

RESET input sets the input mode.

The port 13 block diagram is shown in Figure 6-23.

Caution When only either one of the D/A converter channels is used with AV

REF1

< V

, the other

pins that are not used as analog outputs must be set as follows:

• Set PM13x bit of the port mode register 13 (PM13) to 1 (input mode) and connect the pin

to V

• Set PM13x bit of the port mode register 13 (PM13) to 0 (output mode) and the output latch

to 0, to output low level from the pin.

Figure 6-23. Block Diagram of P130 and P131

PUO : Pull-up resistor option register

: Port mode register

: Port 13 read signal

WR : Port 13 write signal

P-ch

PORT

PUO

Selector

PUO13

Output Latch
(P130, P131)

PM130, PM131

Internal bus

P130/ANO0,
P131/ANO1