cs4297 Cirrus Logic, Inc., cs4297 Datasheet - Page 26

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

Record Gain Register (Index 1Ch)
This register controls the input gain on the analog source which is applied after the input mux and before
the ADCs. The 4-bit value allows for 0 dB to +22.5 dB of gain in 1.5 dB steps. The most significant bit of
the register controls an analog Mute which mutes the signal prior to the ADCs. The following table shows
the possible gain values available:
The default value for this register is 8000h, which corresponds to 0 dB gain with mute on.
Record Gain Mix (Index 1Eh)
The CS4297 does not support the optional 3rd ADC for the MIC PCM input. The Record Gain Mix register
has no function in The CS4297. Writes to this register are ignored, and reads from this register will always
return 0000h.
General Purpose Register (Index 20h)
This register controls miscellaneous facets of the CS4297 mixer. The only bits which have defined func-
tions in the CS4297 are the MIX, MS, and LPBK bits. The MIX bit selects which data to send to the Mono
Output Path. A ‘cleared’ value enables the Mono Mix out (a mix of the 5 analog stereo sources plus
PCM_OUT), while a ‘set’ value passes the MIC to the output. The MS (Mic Select) bit determines which
of the 2 MIC inputs are passed to the rest of the mixer. A ‘cleared’ value selects the MIC1 input, while a
‘set’ value selects the MIC2 input. The LPBK bit enables ADC/DAC Loopback Mode which is used to
facilitate performance evaluation of the CS4297.
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Mute
D15
D15
0
D14
D14
X
0
D13
D13
X
0
D12
D12
X
0
GL3
D11
D11
0
Gx3 - Gx0
GL2
D10
D10
Table 5. Input Mux Selection Options
0
0000
1111
GL1
MIX
D9
D9
GL0
D8
MS
D8
LPBK
D7
D7
X
CrystalClear™ SoundFusion™ Audio Codec ’97
D6
D6
X
0
+22.5 dB
Gain
0 dB
D5
D5
X
0
D4
D4
X
0
GR3
D3
D3
0
GR2
D2
D2
0
GR1
D1
D1
0
CS4297
DS242F5
GR0
D0
D0
0