VS1011 Datasheet, PDF (27/43 Pages) List of Unclassifed Manufacturers – MP3 AUDIO CODEC

VLSI
Solution ^y
VS1011 PRELIMINARY
VS1011
8. FUNCTIONAL DESCRIPTION
8.6.3 SCI BASS (RW)
Name
Bits Description
SB AMPLITUDE 7..4 Enhancement in 1 dB steps (0..15)
SB FREQLIMIT 3..0 Lower limit frequency in 10 Hz steps (2..15)
The Bass Enhancer VSBE is a powerful bass boosting DSP algorithm, which tries to take the most out
of the users earphones without causing clipping.
VSBE is activated when SB AMPLITUDE is set to non-zero. SB AMPLITUDE should be set to the
user’s preferences, and SB FREQLIMIT to roughly 1.5 times the lowest frequency the user’s audio
system can reproduce.
Note: Because VSBE tries to avoid clipping, it gives the best bass boost with dynamical music material,
or when the playback volume is not set to maximum.
8.6.4 SCI CLOCKF (RW)
SCI CLOCKF is used to tell if the input clock XTALI is running at something else than 24.576 MHz.
XTALI
is
set
in
2
kHz
steps.
Thus,
the
formula
for
calculating
the
correct
value
for
this
register
is
XT ALI
2000
(XTALI is in Hz). Values may be between 0..32767, although hardware limits the highest allowed speed.
Also, with speeds lower than 24.576 MHz all sample rates and bitstream widths are no longer available.
Setting the MSB of SCI CLOCKF to 1 activates internal clock-doubling. A clock of upto 15 MHz may
be doubled depending on the voltage provided to the chip.
Note: SCI CLOCKF must be set before beginning decoding audio data; otherwise the sample rate will
not be set correctly.
Note: SCI CLOCKF needs to be rewritten after each software reset. This is different from how VS1002
operates.
Example
1:
For
a
26
MHz
clock
the
value
would
be
26000000
2000
=
13000.
Example 2: For a 13 MHz external clock and using internal clock-doubling for a 26 MHz internal
frequency,
the
value
would
be
0x8000
+
13000000
2000
=
39268.
Example
3:
For
a
24.576
MHz
clock
the
value would
be
either
24576000
2000
=
12288,
or
just
the
default
value 0. For this clock frequency, SCI CLOCKF doesn’t need to be set.
8.6.5 SCI DECODE TIME (RW)
When decoding correct data, current decoded time is shown in this register in full seconds.
The user may change the value of this register. However, in that case the new value should be written
Version 0.71, 2004-07-20
27