WM8994 Datasheet, PDF (97/359 Pages) Wolfson Microelectronics plc – Multi-Channel Audio Hub CODEC for Smartphones

Production Data
WM8994
REGISTER BIT
ADDRESS
LABEL DEFAULT
DESCRIPTION
will cause the DAC volume to ramp up
gradually to the AIF1DAC2L_VOL and
AIF1DAC2R_VOL settings
Table 40 AIF1 Input Path Soft Mute Control
AIF1 - INPUT PATH MONO MIX AND DE-EMPHASIS FILTER
A digital mono mix can be selected on one or both pairs of AIF1 input channels. The mono mix is
generated as the sum of the Left and Right AIF channel data. When the mono mix function is
enabled, the combined mono signal is applied to the Left channel and the Right channel of the
respective AIF1 signal processing and digital mixing paths. To prevent clipping, 6dB attenuation is
applied to the mono mix.
Digital de-emphasis can be applied to the AIF1 input (playback) paths; this is appropriate when the
data source is a CD where pre-emphasis is used in the recording. De-emphasis filtering is available
for sample rates of 48kHz, 44.1kHz and 32kHz. See “Digital Filter Characteristics “section for details
of de-emphasis filter characteristics.
REGISTER BIT
ADDRESS
LABEL DEFAULT
DESCRIPTION
R1056 (0420h) 7
AIF1 DAC1
Filters (1)
AIF1DAC1_
MONO
0
AIF1DAC1 input path (AIF1, Timeslot 0) Mono
Mix Control
0 = Disabled
1 = Enabled
2:1 AIF1DAC1_
00
AIF1DAC1 input path (AIF1, Timeslot 0) De-
DEEMP [1:0]
Emphasis Control
00 = No de-emphasis
01 = 32kHz sample rate
10 = 44.1kHz sample rate
11 = 48kHz sample rate
R1058 (0422h) 7
AIF1 DAC2
Filters (1)
AIF1DAC2_
MONO
0
AIF1DAC2 input path (AIF1, Timeslot 1) Mono
Mix Control
0 = Disabled
1 = Enabled
2:1 AIF1DAC2_
00
AIF1DAC2 input path (AIF1, Timeslot 1) De-
DEEMP [1:0]
Emphasis Control
00 = No de-emphasis
01 = 32kHz sample rate
10 = 44.1kHz sample rate
11 = 48kHz sample rate
Table 41 AIF1 Input Path Mono Mix and De-Emphasis Filter Control
AIF2 - OUTPUT PATH VOLUME CONTROL
The AIF2 interface supports two output channels. A digital volume control is provided on each output
signal path, allowing attenuation in the range -71.625dB to +17.625dB in 0.375dB steps. The level of
attenuation for an eight-bit code X is given by:
0.375  (X-192) dB for 1  X  239; MUTE for X = 0 +17.625dB for 239  X  255
The AIF2ADC_VU bit controls the loading of digital volume control data. When AIF2ADC_VU bit is set
to 0, the AIF2ADCL_VOL and AIF2ADCR_VOL control data will be loaded into the respective control
register, but will not actually change the digital gain setting. Both left and right gain settings are
updated when a 1 is written to AIF2ADC_VU. This makes it possible to update the gain of left and
right channels simultaneously.
w
PD, April 2012, Rev 4.4
97