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STA016T

1

OVERVIEW

The device can decode/process data coming from three possible sources, as showed in Figure 2:

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CDDSP serial link: using this input interface, besides MP3 encoded data CD, it’s possible to playback

also standard Audio CD using the available volume and tone equalizer features of the device and

allowing the use of only one D/A converter with no external analog switch.

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SDI input interface: through this input interface it’s possible to decode any MP3 bitstream coming, for

instance, from an external flash memory. This same interface is also used to decode ADPCM streams.

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compression based on 4 different ADPCM algorithm) or to process an external audio source (tuner, for

instance) through the DSP based volume and tone controls:this BYPASS mode can avoid the use of

additional D/A converters or postprocessing units.

1.1 MP3 decoder engine

The MP3 decoder engine is able to decode any Layer III compliant bitstream: MPEG1, MPEG2 and MPEG2.5

streams are supported.

Decoded audio data goes through a software volume control and a two-band equalizer blocks before feeding

Table 1. MPEG Sampling Rates (KHz)

1.2 ADPCM encoder/decoder engine

This device also embeds a multistandard ADPCM encoder/decoder supporting different sample rates (from 8

KHz up to 32 KHz) and different sample sizes (from 8 bit to 32 bits). During encoding process two different in-

terfaces can be used to feed data: the serial input interface (same interface used also to feed MP3 bitstream)

or the ADC input interface, which provides a seamless connection with an external A/D converter. The currently

used interface is selected via I2C bus.

Also to retrieve encoded data a specific interface is available: the fast GPSO output interface. GPSO interface

is able to output data with a bitrate up to 5 Mbit/s and its control pins (GPSO_SCKR, GPSO_DATA and

GPSO_REQ) can be configured in order to easily fit the target application.

MPEG 1

MPEG 2

MPEG 2.5

48

24

12

44.1

22.05

11.025

32

16

8