PC87393 datasheet(22/148 Pages) NSC

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1.0 Signal/Pin Connection and Description (Continued)

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1.5.10

Serial Port 1 and Serial Port 2 (SP1 and SP2)

Signal

Pin/s

I/O Buffer Type Power Well

Description

CTS1

CTS2

IINTS

VDD

Clear to Send. When low, indicate that the modem or other data

transfer device is ready to exchange data.

DCD1

DCD2

IINTS

VDD

Data Carrier Detected. When low, indicate that the modem or

other data transfer device has detected the data carrier.

DSR1

DSR2

IINTS

VDD

Data Set Ready. When low, indicate that the data transfer device,

e.g., modem, is ready to establish a communications link.

DTR1_

BOUT1

DTR2_

BOUT2

OO3/6

VDD

Data Terminal Ready. When low, indicate to the modem or other

data transfer device that the UART is ready to establish a

communications link. After a system reset, these pins provide the

DTR function and set these signals to inactive high. Loopback

operation holds them inactive.

Baud Output. Provides the associated serial channel baud rate

generator output signal if test mode is selected, i.e., bit 7 of the

EXCR1 register is set.

DTR1_BOUT1 is used also as BADDR.

RI1

RI2

IINTS

VDD

Ring Indicator. When low, indicate that a telephone ring signal

has been received by the modem. They are monitored during

power-off for wake-up event detection.

RTS1

RTS2

OO3/6

VDD

Request to Send. When low, indicate to the modem or other data

transfer device that the corresponding UART is ready to exchange

data. A system reset sets these signals to inactive high, and

loopback operation holds them inactive.

RTS1 is used also as TEST.

SIN1

SIN2

IINTS

VDD

Serial Input. Receive composite serial data from the

communications link (peripheral device, modem or other data

transfer device).

SOUT1

SOUT2

OO3/6

VDD

Serial Output. Send composite serial data to the communications

link (peripheral device, modem or other data transfer device).

These signals are set active high after a system reset.

PC87393 Datasheet(PDF) 22 Page - National Semiconductor (TI)

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