NEC PD78055 Benutzerhandbuch

149

CHAPTER 6 PORT FUNCTIONS

P-ch

PORT

PUO

Selector

PUO13

Output Latch
(P130 and P131)

PM130, PM131

Internal bus

P130/ANO0,
P131/ANO1

6.2.11 Port 13

This is a 2-bit input/output port with output latches. Input mode/output mode can be specified bit-wise by means

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

can be used as a 2-bit unit by means of pull-up resistor option register H (PUOH).

Alternate function includes D/A converter analog output.

RESET input sets the input mode.

Figure 6-18 shows a block diagram of port 13.

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 PM13. 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 6-18. P130 and P131 Block Diagram

PUO : Pull-up resistor option register

: Port mode register

: Port 13 read signal

WR : Port 13 write signal