CS4297 Datasheet, PDF (25/46 Pages) Cirrus Logic – CrystalClear SoundFusion Audio Codec 97

CS4297
CrystalClear™ SoundFusion™ Audio Codec ’97
Stereo Analog Mixer Input Gain Registers (Index 10 - 18h)
D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0
Mute X
X GL4 GL3 GL2 GL1 GL0 X
X
X GR4 GR3 GR2 GR1 GR0
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.
Gx4 - Gx0
00000
00001
…
00111
01000
01001
…
11111
Gain Level
+12 dB
+10.5 dB
…
+1.5 dB
0 dB
-1.5 dB
…
-34.5 dB
Table 3. Analog Mixer Input Gain Values
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)
D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0
X
X
X
X
X SL2 SL1 SL0 X
X
X
X
X SR2 SR1 SR0
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:
Sx2 - Sx0
0
1
2
3
4
5
6
7
Record Source
MIC
CD Input
Video Input
AUX Input
Line Input
Stereo Mix
Mono Mix
Phone Input
Table 4. Input Mux Selection Options
The default power-on value for this register is 0000h, selecting the MIC inputs for both channels.
DS242F5
25