Cirrus Logic CS4205 - Manual (Page 30)

CS4205
30 DS489PP4
5.7 Microphone Volume Register (Index 0Eh)
Mute Microphone Mute. Setting this bit mutes the MIC1 or MIC2 signal. The selection of the MIC1
or MIC2 input pin is controlled by the MS bit in the General Purpose Register (Index 20h).
20dB Microphone 20 dB Boost. When ‘set’, the 20dB bit enables the +20 dB microphone boost
block. In combination with the 10dB boost bit in the Misc. Crystal Control Register (Index 60h)
this bit allows for variable boost from 0 dB to +30 dB in steps of 10 dB. Table 6 summarizes
this behavior.
GN[4:0] Microphone Volume Control. The GN[4:0] bits are used to control the gain level of the Micro-
phone input source to the Input Mixer. Each step corresponds to 1.5 dB gain adjustment, with
01000 = 0 dB. The total range is +12 dB to -34.5 dB gain. See Table 6 for further details.
Default 8008h. This value corresponds to 0 dB gain and Mute ‘set’.
D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0
Mute 0 0 0 0 0 0 0 0 20dB 0 GN4 GN3 GN2 GN1 GN0
GN4 - GN0
Gain Level
10dB = 0,
20dB = 0
10dB = 1,
20dB = 0
10dB = 0,
20dB = 1
10dB = 1,
20dB = 1
00000 +12.0 dB +22.0 dB +32.0 dB +42.0 dB
00001 +10.5 dB +20.5 dB +30.5 dB +40.5 dB
… … ... ... ...
00111 +1.5 dB +11.5 dB +21.5 dB +31.5 dB
01000 0.0 dB +10.0 dB +20.0 dB +30.0 dB
01001 -1.5 dB +8.5 dB +18.5 dB +28.5 dB
… … ... ... ...
11111 -34.5 dB -24.5 dB -14.5 dB -4.5 dB
Table 6. Microphone Input Gain Values