AT80SND1C-ROTIL datasheet(65/210 Pages) ATMEL

65 / 210 page

AT8xC51SND1C

4109E–8051–06/03

Frame Information

The MP3 frame header contains information on the audio data contained in the frame.

These informations is made available in the MP3STA register for you information.

MPVER and MPFS1:0 bits allow decoding of the sampling frequency according to

Table 71. MPVER bit gives the MPEG version (2 or 1).

Table 71. MP3 Frame Frequency Sampling

Ancillary Data

MP3 frames also contain data bits called ancillary data. These data are made available

in the MP3ANC register for each frame. As shown in Figure 45, the ancillary data are

available by Bytes when MPANC flag in MP3STA register is set. MPANC flag is set

when the ancillary buffer is not empty (at least one ancillary data is available) and is

cleared only when there is no more ancillary data in the buffer. This flag can generate an

interrupt as explained in Section "Interrupt", page 66. When set, software must read all

Bytes to empty the ancillary buffer.

Figure 45. Ancillary Data Block Diagram

MPVER

MPFS1

MPFS0

Fs (kHz)

22.05 (MPEG II)

24 (MPEG II)

16 (MPEG II)

Reserved

44.1 (MPEG I)

48 (MPEG I)

32 (MPEG I)

Reserved

Ancillary

Data To C51

MP3ANC

MPANC

MP3STA.7

7-Byte

Ancillary Buffer

AT80SND1C-ROTIL Datasheet(PDF) 65 Page - ATMEL Corporation