CS4297 Datasheet, PDF (26/46 Pages) Cirrus Logic – CrystalClear SoundFusion Audio Codec 97

CS4297
CrystalClear™ SoundFusion™ Audio Codec ’97
Record Gain Register (Index 1Ch)
D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0
Mute X
X
X GL3 GL2 GL1 GL0 X
X
X
X GR3 GR2 GR1 GR0
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:
Gx3 - Gx0
1111
0000
Gain
+22.5 dB
0 dB
Table 5. Input Mux Selection Options
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)
D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0
0
0
0
0
0
0 MIX MS LPBK 0
0
0
0
0
0
0
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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