AD1985 Analog Devices, AD1985 Datasheet - Page 31

• Manufacturer Part Number: AD1985
• Description: AC'97 2.3 Soundmax Codec W/jack Sensing
• Manufacturer: Analog Devices

Surround Volume Control Register (Index 0x38)
Reg Num Name
0x38
This register controls the Surround volume controls for both
stereo channels and mute bits. Each volume subregister contains
five bits, generating 32 volume levels with increments of 1.5 dB
each. Because AC ’97 defines 6-bit volume registers, to maintain
compatibility, whenever the D5 or D13 bit is set to 1, its
respective lower five volume bits are automatically set to 1 by the
codec logic. On read-back all lower five bits will read 1s
whenever these bits are set to 1.
RSR[5:0]
RSM
LSR[5:0]
LSM
LSM (RSM)
0
0
0
0
1
Note: x in the above table is a wild card, meaning the value has no effect.
1
indeterminate since the five LSBs are listed as wild cards.
When AC97NC is set to 1, there is only a 5-bit gain/attenuator to control, so the sixth bit, i.e., the MSB, does not control anything. Therefore, the 5-bit gain setting is
Surround Volume
WRITE
00 0000
00 1111
01 1111
1x xxxx
xx xxxx
Right Surround Volume Control.
Right Surround Volume Mute. When this bit is set to 1, the right channel is muted.
Left Surround Volume Control.
Left Surround Volume Mute. When this bit is set to 1, the left channel is muted.
xSR5–xSR0
D15 D14 D13 D12 D11 D10 D9
LSM X
READBACK
00 0000
00 1111
01 1111
01 1111
xx xxxx
LSR5 LSR4 LSR3 LSR2 LSR1 LSR0 RSM X
Function with AC97NC = 0
0 dB Gain
–22.5 dB Gain
–46.5 dB Gain
–46.5 dB Gain
Muted, -∝ dB Gain
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Note that depending on the state of the AC97NC bit in
Register 0x76, this register operates as follows:
D8
For AC97NC = 0, the register controls the Surround output
pin attenuators. The range is 0 dB to –46.5 dB.
For AC97NC = 1, the register controls the Surround DAC
gain/attenuators. The range is +12 dB to –34.5 dB.
D7
D6 D5
Function with AC97NC = 1
+12 dB Gain
–10.5 dB Gain
–34.5 Gain
Indeterminate
Muted, -∝ dB Gain
RSR5 RSR4 RSR3 RSR2 RSR1 RSR0 0x8080
D4
1
D3
D2
D1
D0
AD1985
Default