ST16C552AIJ68 datasheet(4/39 Pages) EXAR

4 / 39 page

ST16C552/552A

Rev. 3.40

SYMBOL DESCRIPTION

Symbol

Signal Type

Pin Description

-ERROR

Error, Printer (with internal pull-up) - General purpose input

or line printer error. This pin may be connected to the active

low (logic 0) output of a printer to indicate an error condition.

GND

2,7,54

Pwr

Signal and Power Ground.

INIT

I/O

Initialize (open drain, with internal pull-up) - General pur-

pose I/O signal. This pin may be connected for initialization

service of a connected line printer. Generally when this

signal is a logic 0, any connected printer will be initialized.

INT A/B

45,60

Interrupt output A/B ( three state active high) - These pins

provide individual channel interrupts, INT A-B. INT A-B are

enabled when MCR bit-3 is set to a logic 1, interrupts are

enabled in the interrupt enable register (IER), and when an

interrupt condition exists. Interrupt conditions include: re-

ceiver errors, available receiver buffer data, transmit buffer

empty, or when a modem status flag is detected.

-INTP

Printer Interrupt,

- This pin can be used to signal the

interrupt status of a connected printer. This pin basically

tracks the -ACK input pin, When INTSEL is a logic 0 and

interrupts are enabled by bit-4 in the control register. A

latched mode can be selected by setting INTSEL to a logic

1. In this case the interrupt -INTP is generated normally but

does not return to the inactive state until the trailing edge of

the read cycle (-IOR pin). -INTP is three stated until CON

bit-4 is set to a logic 1. The difference between the

ST16C552 and ST16C552A is the output state of INTP.

INTP is active high (logic 1) on the ST16C552 whereas

INTP is active low (logic 0) on the ST16C552A part when the

interrupt latch mode is selected.

INTSEL

Interrupt Select mode - This pin selects the interrupt type for

the printer port (-INTP). When this pin is a logic 0, the

external -ACK signal state is generally followed, minus

some minor propagation delay. Making this pin a logic 1 or

connecting it to VCC will set the interrupt latched mode. In this

case the printer interrupt (-INTP) will not return to a logic 0 on

the 552 or a logic 1 on the 552A (552A is inverted), until the

ST16C552AIJ68 Datasheet(PDF) 4 Page - Exar Corporation

ST16C552AIJ68 Datasheet(HTML) 4 Page - Exar Corporation

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39

Datasheet Download

Link URL