DS020-7 Oct ‘06

©2006 REG No 277 4001, ENGLAND.

Page 6

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The connector provides serial link and audio link to the modem.

Pin number

Name

EIA designation

Type

Note

1

DCD

Data Carrier Detect

Output

2

TX

Transmit Data

Input

3

BOOT

Input

Not used

4

MICROPHONE (+)

Input

5

MICROPHONE (-)

Input

6

RX

Receive Data

Output

7

DSR

Data Set Ready

Output

8

DTR

Data Terminal Ready

Input

9

GND

Ground

Ground

10

SPEAKER(+)

Output

11

CTS

Clear to Send

Output

12

RTS

Request to Send

Input

13

RI

Ring Indicator

Output

14

RESET

Input

Pull low to reset

15

SPEAKER(-)

Output

Specification of microphone and speaker to be connected :

Parameters

Min

Typical

Max

Remark

Microphone current @2V / 2K Ohm

0.5 mA

Microphone input level

100

mVpp

Speaker output current 150 Ohm/

1nF

16mA

Speaker impedance

32ohm

Please refer to the document “Application notes - Power supply & Audio” for more information of audio connection.

Pin assignment of 4-pin connector

Pin number

Name

Functions

1

I/O

Input / Output port

2

~INTR

Interrupt function triggered by pulling this pin to

ground or LOW level; reserved for additional

functions with new firmware

3

POWER -

DC power negative input

4

POWER +

DC power positive input