WM8918 Datasheet, PDF (42/176 Pages) Cirrus Logic – Ultra Low Power DAC for Portable Audio Applications

WM8918
Production Data
DIGITAL MICROPHONE VOLUME CONTROL
The output of the Digital Microphone DSP can be digitally amplified or attenuated over a range from -
71.625dB to +17.625dB in 0.375dB steps. The volume of each channel can be controlled separately.
The gain for a given eight-bit code is detailed in Table 10.
The DMIC_VU bit controls the loading of digital volume control data. When DMIC_VU is set to 0, the
DMICL_VOL or DMICR_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 DMIC_VU. This makes it possible to update the gain of both channels simultaneously.
REGISTER
ADDRESS
R36 (24h)
DMIC Digital
Volume Left
BIT
LABEL
8
DMIC_VU
7:0 DMICL_VOL
[7:0]
DEFAULT
0
1100_0000
(0dB)
R37 (25h)
8
DMIC_VU
0
DMIC Digital
Volume Right
7:0 DMICR_VOL 1100_0000
[7:0]
(0dB)
Table 9 Digital Microphone Volume Control
DESCRIPTION
Digital Microphone Volume Update
Writing a 1 to this bit will cause left
and right DMIC volume to be updated
simultaneously
Left Digital Microphone Volume
00h = Mute
01h = -71.625dB
02h = -71.250dB
… (0.375dB steps)
C0h = 0dB
… (0.375dB steps)
EFh to FFh = +17.625dB
(See Table 10 for volume range)
Digital Microphone Volume Update
Writing a 1 to this bit will cause left
and right DMIC volume to be updated
simultaneously
Right Digital Microphone Volume
00h = Mute
01h = -71.625dB
02h = -71.250dB
… (0.375dB steps)
C0h = 0dB
… (0.375dB steps)
EFh to FFh = +17.625dB
(See Table 10 for volume range)
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PD, Rev 4.1, January 2012
42