Production Data
WM8945
AUX1_TO_PGAR
_ATTEN
0
AUX1 Audio Input to Right Speaker
PGA Mixer attenuation
0
0 = 0dB
1 = -6dB attenuation
Table 32 Right Speaker PGA Mixer (MIXSPKR) Control
SPEAKER PGA VOLUME CONTROL
The volume control of the left and right Speaker PGAs can be independently adjusted using the
SPKL_VOL and SPKR_VOL register fields as described in Table 33. The gain range is
+6dB in 1dB steps.
-57dB to
Note that the output from the Speaker PGA Volume control is an input to the Speaker Output control
described in the following section.
To prevent “zipper noise”, a zero-cross function is provided on the Speaker PGAs. When this feature
is enabled, volume updates will not take place until a zero-crossing is detected. In the case of a long
period without zero-crossings, a timeout function is provided. When the zero-cross function is
enabled, the volume will update after the timeout period if no earlier zero-cross has occurred. The
timeout clock is enabled using TOCLK_ENA. See “Clocking and Sample Rates” for the definition of
this bit.
The SPK_VU bits control the loading of the Speaker PGA volume data. When SPK_VU is set to 0, the
volume control data will be loaded into the respective control register, but will not actually change the
gain setting. The left and right Speaker PGA volume settings are both updated when a 1 is written to
either SPK_VU bit. This makes it possible to update the gain of the left and right output paths
simultaneously.
The Speaker PGA volume control register fields are described in Table 33.
REGISTER
ADDRESS
BIT
LABEL
SPK_VU
DEFAULT
DESCRIPTION
R47 (2Fh)
0
Speaker PGA Volume Update
8
Left SPK
volume ctrl
Writing a 1 to this bit will cause the
Left and Right Speaker PGA
volumes to be updated
simultaneously.
SPKL_ZC
0
1
Left Speaker PGA Zero Cross
Detector
7
0 = Change gain immediately
1 = Change gain on zero cross only
Left Speaker PGA Mute
0 = Disable Mute
SPKL_PGA_
MUTE
6
1 = Enable Mute
SPKL_VOL
11_1001
(0dB)
Left Speaker PGA Volume
00_0000 = -57dB gain
00_0001 = -56dB
5:0
…
11_1001 = 0dB
...
11_1111 = +6dB
(See Table 34 for volume range)
Speaker PGA Volume Update
R48 (30h)
SPK_VU
0
0
8
7
Right SPK
volume ctrl
Writing a 1 to this bit will cause the
Left and Right Speaker PGA
volumes to be updated
simultaneously.
SPKR_ZC
Right Speaker PGA Zero Cross
Detector
0 = Change gain immediately
1 = Change gain on zero cross only
PD, May 2011, Rev 4.1
55
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WOLFSON [ WOLFSON MICROELECTRONICS PLC ]
