AT83C51SND1C_03 ATMEL [ATMEL Corporation], AT83C51SND1C_03 Datasheet - Page 62

• Manufacturer Part Number: AT83C51SND1C_03
• Description: Single-Chip Flash Microcontroller with MP3 Decoder and Human Interface
• Manufacturer: ATMEL [ATMEL Corporation]

MP3 Decoder
Decoder
Description
Figure 42. MP3 Decoder Block Diagram
62
CLOCK
Audio Data
From C51
MP3
AT8xC51SND1C
MP3CON.7
MPEN
8
MPBBST
MP3CON.6
Frame Buffer
MPxREQ
MP3STA1.n
1K Bytes
MP3DAT
The AT8xC51SND1C implement a MPEG I/II audio layer 3 decoder better known as
MP3 decoder.
In MPEG I (ISO 11172-3) three layers of compression have been standardized support-
ing three sampling frequencies: 48, 44.1, and 32 kHz. Among these layers, layer 3
allows highest compression rate of about 12:1 while still maintaining CD audio quality.
For example, 3 minutes of CD audio (16-bit PCM, 44.1 kHz) data, which needs about
32M bytes of storage, can be encoded into only 2.7M bytes of MPEG I audio layer 3
data.
In MPEG II (ISO 13818-3), three additional sampling frequencies: 24, 22.05, and 16 kHz
are supported for low bit rates applications.
The AT8xC51SND1C can decode in real-time the MPEG I audio layer 3 encoded data
into a PCM audio data, and also supports MPEG II audio layer 3 additional frequencies.
Additional features are supported by the AT8xC51SND1C MP3 decoder such as volume
control, bass, medium, and treble controls, bass boost effect and ancillary data
extraction.
The C51 core interfaces to the MP3 decoder through nine special function registers:
MP3CON, the MP3 Control register (see Table 72); MP3STA, the MP3 Status register
(see Table 73); MP3DAT, the MP3 Data register (see Table 74); MP3ANC, the Ancillary
Data register (see Table 76); MP3VOL and MP3VOR, the MP3 Volume Left and Right
Control registers (see Table 77 and Table 78); MP3BAS, MP3MED, and MP3TRE, the
MP3 Bass, Medium, and Treble Control registers (see Table 79, Table 80, and
Table 81); and MPCLK, the MP3 Clock Divider register (see Table 82).
Figure 42 shows the MP3 decoder block diagram.
Anti-Aliasing
MP3VOL
MP3STA.5:3
ERRxxx
MP3VOR
Huffman Decoder
Header Checker
MP3STA.2:1
MPFS1:0
IMDCT
MP3BAS
MP3STA.0
MPVER
MP3MED
Sub-band
Synthesis
Dequantizer
Ancillary Buffer
MP3TRE
MP3ANC
Side Information
16
Stereo Processor
Decoded Data
To Audio Interface
4109E–8051–06/03