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STA016A

3OVERVIEW

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

■

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.

■

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

instance, from an external flash memory.

■

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

D/A converters or postprocessing units.

3.1 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 4. MPEG Sampling Rates (KHz)

Figure 3. Block Diagram

used to move huge amount of data this fast and flexible interface can achieve transfer rates up to 5 Mbit/s.

The embedded DSP firmware implements all the layers required to decode a standard data CD, as shown in

the Figure 4:

MPEG 1

MPEG 2

MPEG 2.5

48

24

12

44.1

22.05

11.025

32

16

8

CDDSP

I/F

SECTOR

BUFFER

SYNC

DETECT.

MMDSP

CORE

- ISO9660 + JOLIET

- BCI

- MP3

DESCRAM.

INPUT SELECTOR

CDROM DECODER (C3)

ECC/EDC

CD_BCK

CD_SDI

CD_LRCK

I/F

BCKI

SDI

LRCKI

STB

RQST

I/F

REG BANK

PLL

OSCK

XTI

XTO

OSC

PCM OUTPUT

BUFFER

I/F

GPSO

I/F

SCL

SDA

GPSO_REQ

GPSO_SDO

GPSO_CK

LRCKO

SDO

BCKO

SDI

I/F

BS_BCK

BS_SDI

BS_LRCK

DREQ

D04AU1565