ST16C452IJ68 データシートの表示（PDF） - Exar Corporation

部品番号

コンポーネント説明

メーカー

ST16C452IJ68

DUAL UART WITH PARALLEL PRINTER PORT

Exar Corporation 

ST16C452/452PS

GENERAL DESCRIPTION

The 452/452PS 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 452/452PS represents such an integration

with greatly enhanced features. The 452/452PS is

fabricated with an advanced CMOS process.

The 452/452PS combines the package functions of a

dual UART and a printer interface on a single inte-

grated chip. The 452/452PS UART is indented to be

software compatible with the ST16C450, and

NS16C450 while the bi-directional printer interface

mode is intended to operate with a CENTRONICS

type parallel printer. However, the printer interface is

designed such that it may be configured to operate

with other parallel printer interfaces or used as a

general purpose parallel interface. The 452 is avail-

able in two versions, the ST16C452 and the

ST16C452PS. The ST16C452 provides single hard-

ware pin to control the printer port data direction while

the 452PS provides an additionally software control

bit to control the printer port data direction to become

compatible PS/2 operating system.

The 452/452PS is capable of operation to 1.5Mbps

with a 24 MHz external clock input. With an external

clock input of 1.8432 MHz the user can select data

rates up to 115.2 Kbps.

FUNCTIONAL DESCRIPTIONS

Functional Modes

Two functional user modes are selectable for the 452/

452PS package. The first of these provides the dual

UART functions, while the other provides the func-

tions of a parallel printer interface. These features are

available through selection at the package interface

select pins.

UART A-B Functions

The UART mode provides the user with the capability

to transfer information between an external CPU and

the 452/452PS package. A logic 0 on chip select pins

-CSA or -CSB allows the user to configure, send data,

and/or receive data via the UART channels A-B.

Printer Port Functions

The Printer mode provides the user with the capability

to transfer information between an external CPU and

the 452/452PS parallel printer port. A logic 0 on chip

select pin -CSP allows the user to configure, send

data, and/or receive data via the bi-directional parallel

8-bit data bus, PD0-PD7.

Internal Registers

The 452/452PS provides 11 internal registers for

monitoring and control of the UART functions and

another 6 registers for monitoring and controlling the

printer port. These resisters are shown in Table 4

below. The UART registers function as data holding

registers (THR/RHR), interrupt status and control

registers (IER/ISR), line status and control registers

(LCR/LSR), modem status and control registers

(MCR/MSR), programmable data rate (clock) control

registers (DLL/DLM), and a user assessable

scratchpad register (SPR). The printer port registers

functions data holding registers (PR), I/O status regis-

ter (SR), I/O select register (IOSEL), and a command

and control register (COM/CON). Register functions

are more fully described in the following paragraphs.

Rev. 3.20

8

Share Link: