Product Preview
WM8581
w
PP Rev 1.0 March 2006
33
REGISTER
ADDRESS
BIT LABEL DEFAULT
DESCRIPTION
7:0
RDA4[7:0] 11111111
(0dB)
Digital Attenuation control for DAC4 Left Channel (DACL4) in 0.5dB
steps. See Table 22.
R26
DIGITAL
ATTENUATION
DACL4
1Ah
8
UPDATE Not
latched Controls simultaneous update of all Attenuation Latches
0 = Store LDA4 in intermediate latch (no change to output)
1 = Apply LDA4 and update attenuation on all channels.
7:0
MASTDA[7:0] 11111111
(0dB)
Digital Attenuation control for DAC4 Right Channel (DACR4) in
0.5dB steps. See Table 22
R27
DIGITAL
ATTENUATION
DACR4
1Bh
8
UPDATE Not
latched ontrols simultaneous update of all Attenuation Latches
0 = Store RDA4 in intermediate latch (no change to output)
1 = Apply RDA4 and update attenuation on all channels.
7:0
MASTDA[7:0] 11111111
(0dB)
Digital Attenuation control for all DAC channels in 0.5dB steps. See
Table 22
R28
MASTER
DIGITAL
ATTENUATION
1Ch
8
UPDATE Not
latched Controls simultaneous update of all Attenuation Latches
0 = Store gain in intermediate latch (no change to output)
1 = Apply gain and update attenuation on all channels.
Table 21 Digital Attenuation Registers
Note:
The volume update circuit of the WM8581 has two sets of registers; LDAx and RDAx. These
can be accessed individually, or simultaneously by writing to MASTDA - Master Digital
Attenuation. Writing to MASTDA will overwrite the contents of LDAx and RDAx.
L/RDAx[7:0] ATTENUATION
LEVEL
00(hex) -
∞
dB (mute)
01(hex) -127.5dB
: :
: :
: :
FE(hex) -0.5dB
FF(hex) 0dB
Table 22 Digital Volume Control Gain Levels
Setting the DACATC register bit causes the left channel attenuation settings to be applied to both left
and right channel DACs from the next audio input sample. No update to the attenuation registers is
required for DACATC to take effect.
REGISTER ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R19
DAC CONTROL 5
13h
6 DACATC
0
Attenuator Control
0 = All DACs use attenuations as
programmed.
1 = Right channel DACs use
corresponding left DAC
attenuations
Table 23 DAC Attenuation Register
The digital volume control also incorporates a zero cross detect circuit which detects a transition
through the zero point before updating the digital volume control with the new volume. This
mechanism helps prevents pops and clicks during volume transitions, and is enabled by control bit
DZCEN.