REV. 0

AD1980

–21–

CNT[5:0]

Center Volume Control

CM

Center Volume Mute. When this bit is set to “1,” the channel is muted.

LFE[5:0]

LFE Volume Control

LM

LFE Volume Mute. When this bit is set to “1,” the channel is muted.

CENTER/LFE Volume Control Register (Index 36h)

Reg

No. Name

D15 D14

D13

*

D12

D11

D10

D9

D8

D7

D6

D5

*

D4

D3

D2

D1

D0

Default

36h Center/LFE

LM

X

LFE5

LFE4

LFE3

LFE2

LFE1

LFE0

CM

X

CNT5 CNT4 CNT3 CNT2

CNT1 CNT0 8080h

Volume

All registers not shown and bits containing an X are assumed to be reserved.

Refer to Table VII for examples. This register controls the LFE output volume and mute bit. The volume registers contain five bit, generating

32 volume levels with 31 steps of 1.5 dB each. If MSPLT is not set, Bit D7 has no effect.

*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 automati-

cally set to “1” by the codec logic. On readback, all lower five bits will read “1”s whenever this bit is set to “1.”

Note that depending on the state of the AC97NC bit in register 76h, this register operates as follows:

For AC97NC = 0, the register controls the center and LFE output pin Attenuators. Range is 0 dB to –46.5 dB.

For AC97NC = 1, the register controls the center and LFE DAC Gain/Attenuators. Range is +12 dB to –34.5 dB.

Table VII. Settings for Center/LFE Register

Control Bits

CENTER and LFE Volume (36h)

CENTER D[5:0] and LFE D[13:8]

D15/D7

WRITE

READBACK

Function with AC97NC = 0

Function with AC97NC = 1

0

00 0000

00 0000

0 dB Gain

12 dB Gain

0

00 1111

00 1111

–22 dB Gain

–10.5 dB Gain

0

01 1111

01 1111

–46.5 dB Gain

–34.5 dB Gain

0

1x xxxx

01 1111

–46.5 dB Gain

Not Applicable

1

xx xxxx

xx xxxx

Muted

Muted

Surround Volume Control Register (Index 38h)

Reg

No.

Name

D15

D14 D13

* D12

D11

D10

D9

D8

D7

D6

D5

*

D4

D3

D2

D1

D0

Default

38h

Surround

MUTE_L X

LSR5 LSR4 LSR3 LSR2

LSR1 LSR0

MUTE_R X

RSR5 RSR4 RSR3 RSR2

RSR1

RSR0 8080h

Volume

*Refer to Table VIII for examples. 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 31 steps 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 coded logic. On readback , all lower five bits will read “1s” whenever

these bits are set to “1.”

Note that depending on the state of the AC97NC bit in Register 0x76, this register operates as follows:

For AC97NC = 0, the register controls the surround output pin Attenuators. Range is 0 dB to –46.5 dB.

For AC97NC = 1, the register controls the surround DAC Gain/Attenuators. Range is +12 dB to –34.5 dB.

RSR[5:0]

Right Surround Volume Control

MUTE_R

Right Surround Volume Mute. When this bit is set to “1,” the right channel is muted.

LSR[5:0]

Left Surround Volume Control

MUTE_L

Left Surround Volume Mute. When this bit is set to “1,” the left channel is muted.