ST16C552AIJ68 查看數據表（PDF） - Exar Corporation

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ST16C552AIJ68

DUAL UART WITH 16-BYTE FIFO AND PARALLEL PRINTER PORT

Exar Corporation 

ST16C552/552A

The rich feature set of the 552/552A is available

through internal registers. Selectable receive FIFO

trigger levels, selectable TX and RX baud rates,

modem interface controls, and a power-down mode

are all standard features. Following a power on reset

or an external reset, the 552/552A is software compat-

ible with the previous generation, 16C452.

FUNCTIONAL DESCRIPTIONS

Functional Modes

Two functional user modes are selectable for the 552/

552A 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 552/552A 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

552/552A 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 552/552A provides 12 internal registers for monitor-

ing 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), a FIFO

control register (FCR), 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 register (SR), I/O select

register (IOSEL), and a command and control register

(COM/CON). Register functions are more fully de-

scribed in the following paragraphs.

Rev. 3.40

9

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