Table 6. microphone input gain values, 7 microphone volume register (index 0eh), Cs4205 – Cirrus Logic CS4205 User 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