REV. 0

AD1981BL

–12–

Mono Volume Register (Index 06h)

Reg

No.

Name

D15

D14

D13

D12

D11

D10

D9

D8

D7

D6

D5

D4

D3

D2

D1

D0

Default

06h

Mono Volume

MVM

X

X

X

X

X

X

X

X

X

X

MV4

MV3

MV2

MV1

MV0

8000h

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

Refer to Table II for examples. This register controls the mono output volume and mute bit. The volume register 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 bit is set to 1, their respective lower five volume bits are automatically set to 1 by the codec logic. On readback, all

lower five bits will read 1s whenever this bit is set to 1.

MV[4:0]

Mono Volume Control. The least significant bit represents 1.5 dB. This register controls the output from 0 dB to a

maximum attenuation of 46.5 dB.

MVM

Mono Volume Mute. When this bit is set to 1, the channel is muted.

Table II. Volume Settings for Mono

Control Bits D[4:0] for Mono (06h)

D15

WRITE

READBACK

Function

0

0000

0 0000

0 dB Gain

00 1111

0 1111

–22.5 dB Gain

01 1111

1 1111

–46.5 dB Gain

1x xxxx

x xxxx

– dB Gain, Muted

x in the above table is a wild card and has no effect on the value.

Phone Volume Register (Index 0Ch)

Reg

No. Name

D15

D14

D13

D12

D11

D10

D9

D8

D7

D6

D5

D4

D3

D2

D1

D0

Default

0Ch Phone Volume

PHM

X

X

X

X

X

X

X

X

X

X

PHV4

PHV3

PHV2

PHV1

PHV0

8008h

All registers not shown and bits containing an X are assumed to be reserved. Refer to Table III for examples.

PHV[4:0]

Phone Volume. Allows setting the phone volume attenuator in 32 volume levels with 31 steps of 1.5 dB each. The

LSB represents 1.5 dB, and the gain range is +12 dB to –34.5 dB. The default value is 0 dB, with the mute bit enabled.

PHM

Phone Mute. When this bit is set to 1, the phone channel is muted.

All registers not shown and bits containing an X are assumed to be reserved. Refer to Table III for examples.

MCV[4:0]

MIC Volume Gain. Allows setting the phone volume attenuator in 32 volume levels with 31 steps of 1.5 dB

each. The LSB represents 1.5 dB, and the gain range is +12 dB to –34.5 dB. The default value is 0 dB, with the mute

bit enabled.

M20

MIC Gain Boost. This bit allows setting additional MIC gain to increase the microphone sensitivity. The nominal

gain boost by default is 20 dB; however, Bits D0 and D1 (MBG[1:0]) on the miscellaneous control bits register

(76h) allow changing the gain boost to 10 dB or 30 dB if necessary.

0 = Disabled; Gain = 0 dB

1 = Enabled; Default Gain = 20 dB (see Register 76h, Bits D0, D1)

MCM

MIC Mute. When this bit is set to 1, the MIC channel is muted.

MIC Volume Register (Index 0Eh)

Reg

No. Name

D15

D14

D13

D12

D11

D10

D9

D8

D7

D6

D5

D4

D3

D2

D1

D0

Default

0Eh MIC Volume

MCM

X

X

X

X

X

X

X

X

M20

X

MCV4

MCV3

MCV2

MCV1 MCV0 8008h

All registers not shown and bits containing an X are assumed to be reserved. Refer to Table III for examples.