wm8400 Wolfson Microelectronics plc, wm8400 Datasheet - Page 76

• Manufacturer Part Number: wm8400
• Description: Wolfson Audioplustm Hi-fi Audio Codec And Power Management Unit For Mobile Multimedia
• Manufacturer: Wolfson Microelectronics plc

WM8400
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DIGITAL SIDETONE
A digital sidetone is available when ADCs and DACs are operating at the same sample rate. Digital
data from either left or right ADC can be mixed with the audio interface data on the left and right DAC
channels. Sidetone data is taken from the ADC high pass filter output, to reduce low frequency noise
in the sidetone (e.g. wind noise or mechanical vibration).
The digital sidetone will not function when ADCs and DACs are operating at different sample rates.
When using the digital sidetone, it is recommended that the ADCs are enabled before un-muting the
DACs to prevent pop noise. The DAC volumes and sidetone volumes should be set to an appropriate
level to avoid clipping at the DAC input.
The digital sidetone is controlled as shown in Table 39.
Table 39 Digital Sidetone Control
Table 40 Digital Sidetone Volume
R14 (0Eh)
ADCL_DAC_SVOL or
REGISTER
ADDRESS
ADCR_DAC_SVOL
0000
0001
0010
0011
0100
0101
0110
0111
1000
1001
1010
1011
1100
1101
1110
1111
12:9
8:5
3:2
1:0
BIT
ADCL_DAC_SVOL
[3:0]
ADCR_DAC_SVOL
[3:0]
ADC_TO_DACL
[1:0]
ADC_TO_DACR
[1:0]
SIDETONE
VOLUME
LABEL
-36
-33
-30
-27
-24
-21
-18
-15
-12
-9
-6
-3
0
0
0
0
0000b
0000b
00b
00b
DEFAULT
Left Digital Sidetone Volume
(See Table 40 for volume range)
Right Digital Sidetone Volume
(See Table 40 for volume range)
Left DAC Digital Sidetone Source
00 = No sidetone
01 = Left ADC
10 = Right ADC
11 = Reserved
Right DAC Digital Sidetone Source
00 = No sidetone
01 = Left ADC
10 = Right ADC
11 = Reserved
DESCRIPTION
PP, April 2009, Rev 3.0
Pre-Production
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