PC87351 datasheet(22/86 Pages) NSC

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1.0 Signal/Pin Connection and Description (Continued)

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1.4.8

Parallel Port

1.4.9

Power and Ground

Signal

Pin/s

I/O

Buffer Type

Description

ACK

INT

Acknowledge. Pulsed low by the printer to indicate that it has received data

from the Parallel Port.

AFD/

DSTRB

OD14, O14/14

AFD - Automatic Feed. When low, instructs the printer to automatically

feed a line after printing each line. This pin is in TRI-STATE after a 0 is

loaded into the corresponding control register bit. An external 4.7 K

Ω pull-

up resistor should be attached to this pin.

DSTRB - Data Strobe (EPP). Active low, used in EPP mode as a data

strobe.

BUSY/WAIT 79

INT

Busy. Set high by the printer when it cannot accept another character.

Wait. In EPP mode, the Parallel Port device uses this active low signal to

extend its access cycle.

ERR

INT

Error. Set active low by the printer when it detects an error.

INIT

OD14-O14/14

Initialize. When low, initializes the printer. This signal is in TRI-STATE

after a 1 is loaded into the corresponding control register bit. Use an

external 4.7 K

Ω pull-up resistor.

PD7-0

81-84,

87, 89,

91, 93

I/O

INT/

OD14, O14/14

Parallel Port Data. Transfer data to and from the peripheral data bus and

the appropriate Parallel Port data register. These signals have a high

current drive capability.

INT

Paper End. Set high by the printer when it is out of paper. This pin has an

internal weak pull-up or pull-down resistor.

PNF

98, 127

INT

Printer Not Floppy. This input from the Parallel Port connector is used to

detect that a ﬂoppy drive is connected to the Parallel Port, and to activates

the PPM. The PNF pin is driven to 1 when a parallel device is connected,

and to 0 when external FDD is connected. This pin is functional only when

the PPM mode is enabled.

SLCT

INT

Select. Set active high by the printer when the printer is selected.

SLIN/

ASTRB

OD14, O14/14

SLIN - Select Input. When low, selects the printer. This signal is in TRI-

STATE after a 0 is loaded into the corresponding control register bit. Uses

an external 4.7 K

Ω pull-up resistor.

ASTRB - Address Strobe (EPP). Active low, used in EPP mode as an

address strobe.

STB/

WRITE

OD14, O14/14

STB - Data Strobe. Indicates to the printer that valid data is available at

the printer port. This signal is in TRI-STATE after a 0 is loaded into the

corresponding control register bit. An external 4.7 K

Ω pull-up resistor

should be employed.

WRITE - Write Strobe. In EPP mode, this active low signal is a write

strobe.

Signal

Pin/s

Buffer Type

Description

VBAT

122

INULR

Battery Power Supply. Provides battery back-up to the System Wake-Up

Control registers, when VSB is lost (power-fail). The pin is connected to the

internal logic through a series resistor for UL protection.

VDD

17, 86

PWR

Main 5V Power Supply.

VSB

123

PWR

Standby Power Supply. Provides 5V power to the Wake-Up Control circuitry,

while the main power supply is turned off.

VSS

18, 51,

85, 116

GND

Ground.

PC87351 Datasheet(PDF) 22 Page - National Semiconductor (TI)

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