User Manual

DM15/25 Integrator’s Manual 16 OF 38

Chassis Ground (GND)

GND is the logical reference of all digital signals in the System Interface as well as the DC return of

the power supply signal, VCC_5V and VCC_12V (used for AMPS burst modes).

Electrical characteristics: I

average

< 0.7 A

peak

< 2 A

Note! That no GND pin can withstand over 0.5 A.

4.1.3.3 MODULE_PWR_EN_B (WAKE)

The MODULE_PWR_EN_B (WAKE) signal is a TTL compatible active high input. This signal (pin

8 on the system connector), is tied to VCC_5V through 330kΩ resistor, recommend open

collector/drain transistor; short this pin to GND to power down the module.

4.1.4 Audio interface

The audio-related signals are: the analog audio signals ATMS (Audio To Mobile Station), and

AFMS (Audio From Mobile Station), and the Pulse Code Modulation (PCM) signals (PCMULD,

PCMDLD, PCMCLK, and PCMSYNC).

Pin DM-15/DM-25 Description

3 AFMS Audio Output From Module

6 ATMS Audio Input to Module

13 PCMCLK External PCM Clock Output

14 PCMSYNC External PCM frame Sync

15 EXTPCMULD External PCM Voice Input

16 PCMDLD External PCM Voice Input

4.1.4.1 Analog Audio

ATMS (pin 6 on the system connector) is the analog audio input to the module. When it is active, it

is connected to the radio via the audio processing stages in the module.

ATMS is also used as the microphone input from the portable Handsfree. When enable via the

AT*NAUD command, a DC bias is provided from the ATMS.

The AFMS (pin 3 on the system connector) is the analog audio output from the module. When it is

active it is connected to the radio via the audio processing stages in the module. The audio signal

then comes out of the output AFMS.

It is also used as a earpiece driver for the Portable Handsfree accessory.