AD1888

Rev. A | Page 13 of 32

Table 9. Headphones Volume Register (Index 04h)

Reg No.

Name

D15

D14

D13

D12

D11

D10

D9

D8

D7

D6

D5

D4

D3

D2

D1

D0

Default

04h

Headphone

Volume

HPM

X

LHV5

LHV4

LHV3

LHV2

LHV1

LHV0

X

RHV5

RHV4

RHV3

RHV2

RHV1

RHV0

8000h

Table 10. Volume Settings for Master and Headphone

Reg. 76h

Control Bits

Master Volume (02h) and Headphone Volume (04h)

MSPLT

T

1

Left Channel Volume D[13:8]

Right Channel Volume D[5:0]

D15

WRITE

READBACK

Function

WRITE

READBACK

Function

0

0

00 0000

00 0000

0 dB Gain

x

00 0000

00 0000

0 dB Gain

0

0

00 1111

00 1111

−22.5 dB Gain

x

00 1111

00 1111

−22.5 dB Gain

0

0

01 1111

01 1111

−46.5 dB Gain

x

01 1111

01 1111

−46.5 dB Gain

0

0

1x xxxx

01 1111

−46.5 dB Gain

x

1x xxxx

01 1111

−46.5 dB Gain

0

1

xx xxxx

xx xxxx

−∞ dB Gain, Muted

x

xx xxxx

xx xxxx

−∞ dB Gain, Muted

1

0

1x xxxx

01 1111

−46.5 dB Gain

1

xx xxxx

xx xxxx

−∞ dB Gain, only

Right Muted

1

1

xx xxxx

xx xxxx

−∞ dB Gain, Left only Muted

0

xx xxxx

xx xxxx

−46.5 dB Gain

1

1

xx xxxx

xx xxxx

−∞ dB Gain, Left Muted

1

xx xxxx

xx xxxx

−∞ dB Gain, Right Muted

MSPLT is not set, Bit D7 has no effect.

x in the above table is don’t care.

Table 11. Mono Volume Register (Index 06h)

Reg

No.

Name

D15

D14

D13

D12

D11

D10

D9

D8

D7

D6

D51

D4

D3

D2

D1

D0

Default

06h

Mono

Volume

MVM

X

X

X

X

X

X

X

X

X

MV5

MV4

MV3

MV2

MV1

MV0

8000h

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. All registers not shown and bits containing an X

are assumed to be reserved.

MV[5:0]

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 12. Volume Settings for Mono

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

D15

WRITE

READBACK

Function

0

0 0000

0 0000

0 dB Gain

0

0 1111

0 1111

−22.5 dB Gain

0

1 1111

1 1111

−46.5 dB Gain

1

x xxxx

x xxxx

−∞ dB Gain, Muted

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