Datasheet

65
4341H–MP3–10/07
AT8xC51SND2C/MP3B
13.2 Audio Controls
13.2.1 Volume Control
The MP3 decoder implements volume control on both right and left channels. The MP3VOR and
MP3VOL registers allow a 32-step volume control according to Table 13-2.
Table 13-2. Volume Control
13.2.2 Equalization Control
Sound can be adjusted using a 3-band equalizer: a bass band under 750 Hz, a medium band
from 750 Hz to 3300 Hz and a treble band over 3300 Hz. The MP3BAS, MP3MED, and
MP3TRE registers allow a 32-step gain control in each band according to Table 13-3.
Table 13-3. Bass, Medium, Treble Control
13.2.3 Special Effect
The MPBBST bit in MP3CON register allows enabling of a bass boost effect with the following
characteristics: gain increase of +9 dB in the frequency under 375 Hz.
13.3 Decoding Errors
The three different errors that can appear during frame processing are detailed in the following
sections. All these errors can trigger an interrupt as explained in Section "Interrupt", page 66.
13.3.1 Layer Error
The ERRSYN flag in MP3STA is set when a non-supported layer is decoded in the header of the
frame that has been sent to the decoder.
13.3.2 Synchronization Error
The ERRSYN flag in MP3STA is set when no synchronization pattern is found in the data that
have been sent to the decoder.
VOL4:0 or VOR4:0 Volume Gain (dB)
00000 Mute
00001 -33
00010 -27
11110 -1.5
11111 0
BAS4:0 or MED4:0 or TRE4:0 Gain (dB)
00000 - ∞
00001 -14
00010 -10
11110 +1
11111 +1.5