Value
Sidetone Gain
Value
Sidetone Gain
0
-32.6dB
8
-8.5dB
1
-30.1dB
9
-6.0dB
2
-26.6dB
10
-2.5dB
3
-24.1dB
11
0dB
4
-20.6dB
12
3.5dB
5
-18.1dB
13
6.0dB
6
-14.5dB
14
9.5dB
7
-12.0dB
15
12.0dB
Table 9.5: Sidetone Gain
Note:
The values of side tone are shown for information only. During standard operation, the application software
controls the sidetone gain.
The following PS Keys configure the side tone hardware:
■
PSKEY_SIDE_TONE_ENABLE
■
PSKEY_SIDE_TONE_GAIN
■
PSKEY_SIDE_TONE_AFTER_ADC
■
PSKEY_SIDE_TONE_AFTER_DAC
9.2.19 Integrated Digital IIR Filter
CSR8640 BGA has a programmable digital filter integrated into the ADC channel of the codec. The filter is a 2-stage,
second order IIR and is for functions such as custom wind noise reduction. The filter also has optional DC blocking.
The filter has 10 configuration words:
■
1 for gain value
■
8 for coefficient values
■
1 for enabling and disabling the DC blocking
The gain and coefficients are all 12-bit 2's complement signed integer with the format
NN.NNNNNNNNNN
.
Note:
The position of the binary point is between bit[10] and bit[9], where bit[11] is the most significant bit.
Advance Information
This material is subject to CSR's non-disclosure agreement
© Cambridge Silicon Radio Limited 2011
Page 46 of 110
CS-209182-DSP1
CSR8640 BGA
Data Sheet