Rainbow Electronics AT89C51SND1C - Manual (Page 64)

64
AT8xC51SND1C
4109E–8051–06/03
Audio Controls
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 69.
Table 69. Volume Control
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 70.
Table 70. Bass, Medium, Treble Control
Special Effect The MPBBST bit in MP3CON register allows enabling of a bass boost effect with the fol-
lowing characteristics: gain increase of +9 dB in the frequency under 375 Hz.
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 "Inter-
rupt", page 66.
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.
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.
CRC Error When the CRC of a frame does not match the one calculated, the flag ERRCRC in
MP3STA is set. In this case, depending on the CRCEN bit in MP3CON, the frame is
played or rejected. In both cases, noise may appear at audio output.
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