WM8945
Production Data
To enable the output PGAs and mixers, the reference voltage VMID and the bias current must also be
enabled. See “Reference Voltages and Master Bias” for details of the associated controls VMID_SEL
and BIAS_ENA.
Note that the Line output, Speaker outputs and Speaker PGA mixers are all muted by default. The
required signal paths must be un-muted using the control bits described in the respective tables
below.
LINE OUTPUT MIXER CONTROL
The Line Output mixer controls are described in Table 30. These allow any of the DAC, Inverted DAC,
AUX1/2 and one of the ADC Bypass signals to be mixed. The output of the mixer can be muted using
the LINEL_MUTE bit.
Care should be taken when mixing more than one path to the Line Output mixer in order to avoid
clipping. The gain of each input path is adjustable using a selectable -6dB control in each path to
facilitate this.
Note that the attenuation control field DACL_TO_OUTL_ATTEN controls the DAC and the Inverted
DAC mixer paths to the Line Output mixer. Note that the DAC input level may also be controlled by
the DAC digital volume control – see “Digital to Analogue Converter (DAC)” for further details.
When the AUX1 or AUX2 pin is used as an audio input, that pin must be configured for audio using
the AUX1_AUDIO or AUX2_AUDIO register bits. These bits are defined in Table 2 (see “Analogue
Input Signal Path”).
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R42 (2Ah)
Output ctrl
LINEL_MUTE
1
LINEOUTL Output Mute
0 = Disable Mute
8
1 = Enable Mute
R49 (31h)
BYPL_TO_OUTL
0
0
Left Input PGA (ADC bypass) to
Left Output Mixer select
6
5
Line L mixer
control 1
0 = Disabled
1 = Enabled
MDACL_TO_
OUTL
Inverted Left DAC to Left Output
Mixer select
0 = Disabled
1 = Enabled
DACL_TO_OUTL
AUX2_TO_OUTL
0
0
Left DAC to Left Output Mixer select
0 = Disabled
3
1
1 = Enabled
AUX2 Audio Input to Left Output
Mixer select
0 = Disabled
1 = Enabled
AUX1_TO_OUTL
0
0
0
AUX1 Audio Input to Left Output
Mixer select
0
6
3
0 = Disabled
1 = Enabled
R51 (33h)
BYPL_TO_OUTL
_ATTEN
Left Input PGA (ADC bypass) to
Left Output Mixer attenuation
Line L mixer
control 2
0 = 0dB
1 = -6dB attenuation
DACL_TO_OUTL
_ATTEN
Left DAC to Left Output Mixer
attenuation
0 = 0dB
1 = -6dB attenuation
PD, May 2011, Rev 4.1
52
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WOLFSON [ WOLFSON MICROELECTRONICS PLC ]
