VS1033 Datasheet, PDF (30/70 Pages) List of Unclassifed Manufacturers – MP3/AAC/WMA/MIDI AUDIO CODEC

VLSI
Solution ^y
VS1033a PRELIMINARY
VS1033A
8. FUNCTIONAL DESCRIPTION
8.3 Data Flow of VS1033
SDI
Bitstream
FIFO
MP3
WAV/ADPCM/
WMA / AAC /
MIDI decode
SM_ADPCM=0
AIADDR = 0
User
Application
AIADDR != 0
SB_AMPLITUDE=0 ST_AMPLITUDE=0
Bass
enhancer
SB_AMPLITUDE!=0
Treble
enhancer
ST_AMPLITUDE!=0
Volume
control
SCI_VOL
Audio
FIFO
2048 stereo
samples
L
S.rate.conv.
and DAC
R
Figure 12: Data Flow of VS1033.
First, depending on the audio data, and provided ADPCM encoding mode is not set, MP3, WMA, AAC,
PCM WAV, IMA ADPCM WAV, or MIDI data is received and decoded from the SDI bus.
After decoding, if SCI AIADDR is non-zero, application code is executed from the address pointed to
by that register. For more details, see Application Notes for VS10XX.
Then data may be sent to the Bass and Treble Enhancer depending on the SCI BASS register.
After that the signal is fed to the volume control unit, which also copies the data to the Audio FIFO.
The Audio FIFO holds the data, which is read by the Audio interrupt (Chapter 10.14.1) and fed to the
sample rate converter and DACs. The size of the audio FIFO is 2048 stereo (2×16-bit) samples, or 8
KiB.
The sample rate converter converts all different sample rates to XTALI/2, or 128 times the highest us-
able sample rate. This removes the need for complex PLL-based clocking schemes and allows almost
unlimited sample rate accuracy with one fixed input clock frequency. With a 12.288 MHz clock, the DA
converter operates at 128 × 48 kHz, i.e. 6.144 MHz, and creates a stereo in-phase analog signal. The
oversampled output is low-pass filtered by an on-chip analog filter. This signal is then forwarded to the
earphone amplifier.
8.4 Serial Data Interface (SDI)
The serial data interface is meant for transferring compressed MP3, WMA, or AAC data, WAV PCM and
ADPCM data as well as MIDI data.
If the input of the decoder is invalid or it is not received fast enough, analog outputs are automatically
muted.
Also several different tests may be activated through SDI as described in Chapter 9.
Version 0.6, 2005-01-05
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