User guide

Confidential, the whole present document is the sole property of Maestro Wireless

Solution Limited.

c. 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

With 2VDC bias

output

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 0.5mA

Microphone input level 100 mVpp

Speaker output current 150 Ohm/1nF 16mA

Speaker impedance 32ohm 50Ohm

Please refer to the document "Application notes - Power supply & Audio" for more

information about audio connection.

d. 4-Pin connector (Power input/output)

A cable, included in the package shall be used for power supply 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