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XE3314B

Low-Cost, Embeddable 33,600 BPS Modem Module

Unspecified 

XE3314B Pin Descriptions

PIN NAME DESCRIPTION

1

NC No Internal Connection

2

AR Auxiliary Data/Voice Relay, Active High Output, TTL/CMOS. The AR signal goes high when ever

the modem is in the on-hook state. It can be connected to an external relay to switch control of the

telephone line between the modem and an auxiliary handset when.

3

RXD Received Data, Output, TTL. Serial data output to the host. A logic "High" on RXD represents a

"mark" and a logic "Low" represents a "space".

4-8

NC No Internal Connection

9

\DTR Data Terminal Ready, Input, active Low, TTL. The "AT&D" command sets the function of \DTR.

The default, AT&D2, requires the host to assert \DTR to permit a modem link. The modem drops the

call in progress if \DTR is revoked and will not connect until \DTR is re-asserted.

10

TST3 Test 3 is used for manufacturing purposes only. It has no function in normal operation.

11

\CTS Clear to Send, Output, active Low, TTL/CMOS. \CTS is used as a Flow Control output from the

modem. The modem revokes \CTS with hardware flow control active to signal the host that the

modem's input buffer is full. The modem reasserts \CTS when the buffer can accept more data

without a buffer overflow.

12

NC No Internal Connection

13

TXD Transmit Data, Input, TTL. Serial data input from the host. A logic "High" represents a "mark" and a

Low represents a"space", TTL.

14

\RTS Request to Send, input, active Low, TTL. The XE3314B uses \RTS for hardware flow control. When

\RTS is revoked; hardware flow control is enabled, and the modem will not place data on RXD.

15

NC No Internal Connection

16

\RI Ring Indicator, Output, active Low, TTL. When low indicates the modem is receiving a ring signal.

18

TIP Tip connection to the phone line(RJ11 pin3) from the internal DAA. The XE3314B is not sensitive to

the battery voltage polarity across Tip and Ring.

20

RING Ring connection to the phone line(RJ11 pin4) from the internal DAA.

21

GND Ground (0 volts)

22

AMP Audio Output function is set by L & M commands and the value in register S22. This output can drive

a minimum load of 300 ohms.

27, 28 TST1, TST2 Test 1 and Test 2 are used for manufacturing test only. They have no function in normal use. These

pins are connected to the telephone line side of the telephone interface circuit so isolation must be

maintained between these signals and all other circuits.

30

OH Off-Hook, Output, active High. OH indicates the modem's hookswitch relay is closed. Hookswitch

closure connects the modem to the telephone line. This signal is available only on the XE3314B.

36

RESET Hardware reset pin, Input, active High, TTL. A high on Pin 36 initiates a hardware reset. An external

reset is not required or recommended. The Reset pulse must be a minimum of 100 milliseconds long

37

N/C

No Internal Connection

38 \DCD

Data Carrier Detect, Output Active Low, TTL/CMOS. The &C command sets the function of \DCD. In

the default state \DCD activates when a valid carrier is detected.

39 \DSR

Data Set Ready, Output, active Low, TTL/CMOS. &S sets the \DSR function. In the default condition,

AT&S0, \DSR is forced true.

40

Vcc

+5 Volts.

XECOM

(3)

XE3314B

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