16C450 Просмотр технического описания (PDF) - Exar Corporation

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16C450

UNIVERSAL ASYNCHRONOUS RECEIVER/TRANSMITTER (UART)

Exar Corporation 

ST16C450

SYMBOL DESCRIPTION

Symbol

-RI

-RTS

RX

TX

Pin

Signal

40 44 48 type

Pin Description

39 43

41

I Ring Indicator (active low) - A logic 0 on this pin indicates the

modem has received a ringing signal from the telephone

line. A logic 1 transition on this input pin will generate an

interrupt.

32

36

32

O Request to Send (active low) - A logic 0 on the -RTS pin

indicates the transmitter has data ready and waiting to send.

Writing a logic 1 in the modem control register (MCR bit-1)

will set this pin to a logic 0 indicating data is available. After

a reset this pin will be set to a logic 1. This pin has no effect

on the UART’s transmit or receive operation.

10 11

7

I Receive Data - This pin provides the serial receive data

input to the ST16C450. The RX signal will be a logic 1 during

reset, idle (no data). During the local loop-back mode, the

RX input pin is disabled and TX data is internally connected

to the UART RX Input, internally, see figure 12.

11 13

8

O Transmit Data - This pin provides the serial transmit data

from the ST16C450, the TX signal will be a logic 1 during

reset, idle (no data). During the local loop-back mode, the

TX input pin is disabled and TX data is internally connected

to the UART RX Input, see figure 12.

GENERAL DESCRIPTION

The ST16C450 provides serial asynchronous receive

data synchronization, parallel-to-serial and serial-to-

parallel data conversions for both the transmitter and

receiver sections. These functions are necessary for

converting the serial data stream into parallel data that

is required with digital data systems. Synchronization

for the serial data stream is accomplished by adding

start and stops bits to the transmit data to form a data

character (character orientated protocol). Data integ-

rity is insured by attaching a parity bit to the data

character. The parity bit is checked by the receiver for

any transmission bit errors. The electronic circuitry to

provide all these functions is fairly complex especially

when manufactured on a single integrated silicon chip.

The ST16C450 represents such an integration with

greatly enhanced features. The ST16C450 is fabricated

with an advanced CMOS process. The ST16C450 is

designed to work with high speed modems and shared

network environments.

The ST16C450 is capable of operation to 1.5Mbps

with a 24 MHz crystal or external clock input.

With a crystal of 14.7464 MHz and through a software

option, the user can select data rates up to 460.8Kbps

or 921.6Kbps.

Rev. 4.20

7

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