Product Preview
WM8955L
TONE CONTROL
The WM8955L provides separate controls for bass and treble with programmable gains and filter
characteristics. This function operates on digital audio data before it is passed to the audio DACs.
Bass control can take two different forms:
•
Linear bass control: bass signals are amplified or attenuated bya user programmable
gain. This is independent of signal volume, and veryhigh bass gains on loud signals
maylead to signal clipping.
•
Adaptive bass boost: The bass volume is amplified bya variable gain. When the bass
volume is low, it is boosted more than when the bass volume is high. This method is
recommended because it prevents clipping, and usuallysounds more pleasant to the
human ear.
Treble control applies a user programmable gain, without anyadaptive boost function.
REGISTER
ADDRESS
BIT
LABEL
BB
DEFAULT
DESCRIPTION
R12 (0Ch)
7
0
0
Bass Mode
Bass Control
0 = Linear bass control
1 = Adaptive bass boost
6
BC
Bass Filter Characteristic
0 = Low Cutoff (130 Hz at 48kHz sampling)
1 = High Cutoff (200 Hz at 48kHz sampling)
Bass Intensity
3:0
BASS
1111 (OFF)
Code
0000
0001
0010
…
BB=0
BB=1
15 (max)
14
+9dB
+9dB
+7.5dB
(1.5dB steps)
0dB
13
…
0111
…
8
(1.5dB steps)
…
1011-1101 -6dB
4-2
1110
1111
-6dB
1 (min)
Bypass (OFF)
R13 (0Dh)
6
TC
0
Treble Filter Characteristic
Treble Control
0 = High Cutoff (8kHz at 48kHz sampling)
1 = Low Cutoff (4kHz at 48kHz sampling)
Treble Intensity
3:0
TRBL
1111
(Disabled)
0000 or 0001 = +9dB
0010 = +7.5dB
… (1.5dB steps)
1011 to 1110 = -6dB
1111 = Disable
Table 3 Tone Control
Note:
1. All cut-off frequencies change proportionallywith the DAC sample rate.
Product Preview Rev 0.4 May2003
17
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WOLFSON [ WOLFSON MICROELECTRONICS PLC ]
