VS1053B Datasheet, PDF (47/79 Pages) List of Unclassifed Manufacturers – Ogg Vorbis/MP3/AAC/WMA/MIDI AUDIO CODEC

VLSI
Solution ^y
VS1053b preliminary
VS1053B
8. FUNCTIONAL DESCRIPTION
8.7.11 SCI VOL (RW)
SCI VOL is a volume control for the player hardware. The most significant byte of the volume register
controls the left channel volume, the low part controls the right channel volume. The channel volume
sets the attenuation from the maximum volume level in 0.5 dB steps. Thus, maximum volume is 0x0000
and total silence is 0xFEFE.
Note, that after hardware reset the volume is set to full volume. Resetting the software does not reset the
volume setting.
Setting SCI VOL to 0xFFFF will activate analog powerdown mode.
Example: for a volume of -2.0 dB for the left channel and -3.5 dB for the right channel: (2.0/0.5) = 4,
3.5/0.5 = 7 → SCI VOL = 0x0407.
Example: SCI VOL = 0x2424 → both left and right volumes are 0x24 * -0.5 = -18.0 dB
In VS1053b bass and treble initialization and volume change is delayed until the next batch of samples
are sent to the audio FIFO. Thus, audio interrupts can no longer be missed during a write to SCI BASS
or SCI VOL.
This delays the volume setting slightly, but because the volume control is now done in the DAC hardware
instead of performing it to the samples going into the audio FIFO, the overall volume change response
is better than before. Also, the actual volume control has zero-cross detection, which almost completely
removes all audible noise that occurs when volume is suddenly changed.
8.7.12 SCI AICTRL[x] (RW)
SCI AICTRL[x] registers ( x=[0 .. 3] ) can be used to access the user’s application program.
The AICTRL registers are also used with IMA ADPCM encoding mode.
Version 0.5, 2007-12-03
47