AD20msp415

–4–

REV. 0

CAUTION

ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily

accumulate on the human body and test equipment and can discharge without detection.

Although the AD20msp415 features proprietary ESD protection circuitry, permanent damage

may occur on devices subjected to high energy electrostatic discharges. Therefore, proper ESD

precautions are recommended to avoid performance degradation or loss of functionality.

Generation of Auxiliary Audio Signals

Under control of Layer 1, the GSMP can generate a variety of

fixed and user-programmable tones. This includes all standard

DTMF and Call Progress tones as well as user defined tones.

The tone structure can consist of up to four frequency compo-

nents with individual durations. The GSMP also generates

Talker Sidetone as specified in the GSM recommendations. In

comparison to traditional hardware implementations, this soft-

ware implementation provides manufacturing flexibility over a

wide range of speaker/microphone sensitivities.

AD6421

SERIAL

VOICE

PORT

SERIAL

AUXILIARY

PORT

AUXILIARY ADC

FILTER

FILTER

ADC

PGA

MUX

CAR

KIT

TEMP

OTHER

ADC

PGA

MUX

MUX

Figure 3. Audio/Auxiliary Section of the AD6421

Figure 3 shows the audio section and the auxiliary ADC of the

VBC. Input signals can come from either a directly connected

microphone or from a remote microphone in a car kit. Input

gain can be set to 0 dB or +26 dB. The output signal can be

directly connected to a small earpiece and, for further amplifica-

tion, to an external car kit. The output PGA can be programmed

for –15 dB or +6 dB.

DATA SERVICES

Data Services is considered to be an essential feature for GSM

terminals and the AD20msp415 chipset is designed to provide

flexible and low cost implementation of Data Services supported

via the GSM air interface.

The selected system architecture shown in Figure 4 provides for

minimum terminal Bill of Materials, the lowest possible number

of interconnection points and the lowest power consumption

when running speech traffic only. The GSMP performs full

channel coding and decoding for TCH/F9.6, TCH/F4.8 and

TCH/F2.4 data rates. The interface to the chipset is a user-

configurable, 3-wire synchronous or asynchronous serial inter-

face supplying V110´ data packets as defined in GSM 05.03,

combined with protocol information and control to the Applica-

tion Layer.

External to the terminal is the Data Terminal Adapter (DTA)

that runs the Data Services Software. Included in the DTA are

the rate adaptation functions and the Data Services application.

The Command Interpreter resident on the mobile supports a

serial interface protocol with the DTA by which both traffic data

and control information are communicated.

V110'

FRAMES

MAN MACHINE INTERFACE

DATA APPLICATION

LAYER 2 RELAY (L2R)

RADIO LINK PROTOCOL (RLP)

RATE ADAPTION

EXTERNAL

DATA TERMINAL

ADAPTER

HANDSET

APPLICATION LAYER

FOREGROUND

COMMAND

INTERPRETER

FRAME

ROUTER

DATA TERMINAL

ADAPTER

APPLICATION LAYER

BACKGROUND

PROTOCOL STACK

LAYERS 2/3

PROTOCOL STACK

LAYER 1

AD20msp415

CHIPSET

Figure 4. Implementation of Data Services

SOFTWARE IMPLEMENTATIONS

A full implementation of the GSM Layer 1 functionality is sup-

plied as an object code module, for execution on the controller,

embedded in the GSMP. Functions performed by this software

include:

• Initial scan of GSM/E-GSM/PCN band and selection of

strongest thirty channels as required by 03.22 and 05.08.

• Mobile oscillator adjustment, timing synchronization and

BCCH decoding from serving cell (camping-on).

• Base station frequency and timing measurements and BSIC

extraction from neighbor cells under control of Layer 3.

• Frequency hopping according to 05.02.

• Full implementation of discontinuous reception (DRX) and

transmission (DTX).

• Reporting of received level and signal quality.

• Full engineering and test mode support.

• Support for all phase 1 and phase 2 handover modes.

• SIM Interface driver.

• Message interfacing to Layer 3 (Radio Resources Manager)

and Layer 2 (data link layer, both signaling and data).

• External functions for AGC, AFC and synthesizer setting are

called by Layer 1. These allow the user to configure the sys-

tem for a wide range of radio architectures.

The higher layers of the protocol stack also reside on this em-

bedded processor.

WARNING!

ESD SENSITIVE DEVICE