wm8351 Wolfson Microelectronics plc, wm8351 Datasheet - Page 73

• Manufacturer Part Number: wm8351
• Description: Wolfson Audioplus? Stereo Codec With Power Management
• Manufacturer: Wolfson Microelectronics plc

Production Data
13.6 DIGITAL MIXING
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13.6.1
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 Table 29.
Table 29 Digital Side Tone Control
The coding of ADCL_DAC_SVOL and ADCR_DAC_SVOL is described in Table 30.
Table 30 Digital Side Tone Control
R68 (44h)
ADC
Divider
R60 (3Ch)
Digital Side
Tone
Control
REGISTER
ADDRESS
ADCL_DAC_SVOL or
ADCR_DAC_SVOL
DIGITAL SIDETONE
0000
0001
0010
0011
0100
0101
0110
0111
1000
1001
1010
1011
1100
1101
1110
1111
13:12
11:10
11:8
BIT
7:4
ADCL_DAC_SVOL
[3:0]
ADCR_DAC_SVOL
[3:0]
ADC_TO_DACL
[1:0]
ADC_TO_DACR
[1:0]
SIDETONE
LABEL
VOLUME
-36
-33
-30
-27
-24
-21
-18
-15
-12
-9
-6
-3
0
0
0
0
DEFAULT
0000
0000
00
00
Left Digital Side tone Volume in dB
(See Table 30 for volume range)
Right Digital Side tone Volume in dB
(See Table 30 for volume range)
DAC Left Side-tone Control
11 = Unused
10 = Mix ADCR into DACL
01 = Mix ADCL into DACL
00 = No Side-tone mix into DACL
DAC Right Side-tone Control
11 = Unused
10 = Mix ADCR into DACR
01 = Mix ADCL into DACR
00 = No Side-tone mix into DACR
DESCRIPTION
PD, June 2009, Rev 4.1
WM8351
73