Production Data
WM8945
SPEAKER OUTPUT CONTROL
Each Speaker output has its own output mixer. This allows the output of the respective Speaker PGA
to be enabled or disabled, and also allows the Auxiliary input AUX1 to be routed directly to either
Speaker output. The two Speaker outputs can be muted also, using the SPKR_OP_MUTE and
SPKL_OP_MUTE.
The AUX1 path can be used to provide a fixed-gain signal path that is unaffected by the Speaker
PGA setting. This feature is intended for a “PC Beep” or similar applications.
Care should be taken when enabling more than one path to the Speaker Output mixers in order to
avoid clipping. The gain of each input path is adjustable using a selectable -6dB control in each path
to facilitate this.
When the AUX1 pin is used as an audio input, that pin must be configured for audio using the
AUX1_AUDIO register bit. This bit is defined in Table 2 (see “Analogue Input Signal Path”).
The Speaker Output control registers are described in Table 35.
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R3 (03h)
SPKR_OP_MUTE
1
SPKOUTR Output Mute
0 = Disable Mute
9
Power
Management
1
1 = Enable Mute
SPKL_OP_MUTE
AUX1_TO_SPKL
1
0
SPKOUTL Output Mute
0 = Disable Mute
8
8
1 = Enable Mute
R43 (2Bh)
AUX1 Audio Input to Left Speaker
Output select
SPK mixer
control 1
0 = Disabled
1 = Enabled
PGAL_TO_SPKL
AUX1_TO_SPKR
PGAR_TO_SPKR
0
0
0
0
0
0
0
Left Speaker PGA Mixer to Left
Speaker Output select
7
8
7
8
7
8
7
0 = Disabled
1 = Enabled
R44 (2Ch)
AUX1 Audio Input to Right Speaker
Output select
SPK mixer
control 2
0 = Disabled
1 = Enabled
Right Speaker PGA Mixer to Right
Speaker Output select
0 = Disabled
1 = Enabled
R45 (2Dh)
AUX1_TO_SPKL_
ATTEN
AUX1 Audio Input to Left Speaker
Output attenuation
SPK mixer
control 3
0 = 0dB
1 = -6dB attenuation
PGAL_TO_SPKL
_ATTEN
Left Speaker PGA Mixer to Left
Speaker Output attenuation
0 = 0dB
1 = -6dB attenuation
R46 (2Eh)
AUX1_TO_SPKR
_ATTEN
AUX1 Audio Input to Right Speaker
Output attenuation
SPK mixer
control 4
0 = 0dB
1 = -6dB attenuation
PGAR_TO_SPKR
_ATTEN
Right Speaker PGA Mixer to Right
Speaker Output attenuation
0 = 0dB
1 = -6dB attenuation
Table 35 Speaker Output Control
PD, May 2011, Rev 4.1
57
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WOLFSON [ WOLFSON MICROELECTRONICS PLC ]
