cs4297 Cirrus Logic, Inc., cs4297 Datasheet - Page 25

• Manufacturer Part Number: cs4297
• Description: Crystalclear Soundfusion Audio Codec 97 Logic
• Manufacturer: Cirrus Logic, Inc.

DS242F5
Stereo Analog Mixer Input Gain Registers (Index 10 - 18h)
These registers control the gain levels of the analog input sources to the Input Mixer. Each register step for
all registers corresponds to 1.5 dB gain adjustment, thus allowing a range of 12 dB to -34.5 dB of gain.
The MSB of these registers control an analog mute for each source to input mixer. Bits Gx4 - Gx0 of the
registers are used to control the gain levels for each source. The gain mapping for these bits is shown in
Table 3.
For the stereo source registers (10h through 18h), the default values are 8808h, corresponding to 0 dB at-
tenuation for both channels, and mute on.
Input Mux Select Register (Index 1Ah)
This register selects the input source to pass to the ADCs for capturing PCM data. The AC’97 specification
allows for independent control of the left and right channels for this mux. Bits SL2 - SL0 provide the de-
code for the left input mux, and bits SR2 - SR0 provide the decode for the right. Shown below are the pos-
sible values for each of these decodes:
The default power-on value for this register is 0000h, selecting the MIC inputs for both channels.
CS4297
CrystalClear™ SoundFusion™ Audio Codec ’97
Mute
D15
D15
X
D14
D14
X
X
D13
D13
X
X
D12
GL4
D12
X
GL3
D11
D11
X
Gx4 - Gx0
D10
GL2
D10
SL2
Table 3. Analog Mixer Input Gain Values
Sx2 - Sx0
00000
00001
01000
01001
00111
11111
Table 4. Input Mux Selection Options
…
…
0
1
2
3
4
5
6
7
GL1
SL1
D9
D9
GL0
SL0
D8
D8
D7
D7
X
X
D6
D6
X
X
Record Source
Gain Level
+10.5 dB
-34.5 dB
Phone Input
+1.5 dB
-1.5 dB
Video Input
+12 dB
Stereo Mix
AUX Input
Line Input
Mono Mix
CD Input
0 dB
…
…
MIC
D5
D5
X
X
GR4
D4
D4
X
GR3
D3
D3
X
GR2
SR2
D2
D2
GR1
SR1
D1
D1
GR0
SR0
D0
D0
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