User manual

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1.2.3. 15-PIN D-SUB Female connector (RS232 / Audio)

- 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.

1.2.4. 4-PIN connector (Power, Input / Output)

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