NEC PD78055 Manuale Utente

CHAPTER 4 PIN FUNCTION (

PD78054Y Subseries)

4.2.10 P130 and P131 (Port 13)

These are 2-bit input/output ports. Besides serving as input/output ports, they are used for D/A converter analog

output.

The following operating modes can be specified in 1-bit units.

(1) Port mode

These ports function as 2-bit input/output ports. They can be specified in 1-bit units as input or output ports

with port mode register 13 (PM13). When they are used as input ports, on-chip pull-up resistors can be used

by defining the pull-up resistor option register H (PUOH).

(2) Control mode

These ports allow D/A converter analog output (ANO0 and ANO1).

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.

4.2.11 AV

REF0

A/D converter reference voltage input pin.

When A/D converter is not used, connect this pin to V

4.2.12 AV

REF1

D/A converter reference voltage input pin.

When D/A converter is not used, connect this pin to V

4.2.13 AV

Analog power supply pin of A/D converter. Always use the same voltage as that of the V

pin even when A/D

converter is not used.

4.2.14 AV

This is a ground voltage pin of A/D converter and D/A converter. Always use the same voltage as that of the V

pin even when neither A/D nor D/A converter is used.

4.2.15 RESET

This is a low-level active system reset input pin.