REV. 0

–14–

AD1980

ROV[4:0]

Right PCM Out Volume. Allows setting the PCM right channel attenuator in 32 volume levels. The LSB represents

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

RM

Right Channel Mute. Once enabled by the MSPLT bit in Register 76h, this bit mutes the right channel separately

from the AVM bit. Otherwise, this bit will always read “0” and will have no affect when set to “1.”

LOV[4:0]

Left PCM Out Volume. Allows setting the PCM left channel attenuator in 32 volume levels. The LSB represents

1.5 dB, and the range is +12 dB to –34.5 dB. The default value is 0 dB, mute enabled.

OM

PCM Out Volume Mute. When this bit is set to “1,” both the left and the right channels are muted, unless the

MSPLT bit in Register 76h is set to “1,” in which case this mute bit will affect only the left channel.

PCM-Out Volume Register (Index 18h)

Reg

No. Name

D15 D14 D13 D12

D11

D10

D9

D8

D7

D6

D5 D4

D3

D2

D1

D0

Default

18h PCM Out Volume OM X

X

LOV4 LOV3

LOV2

LOV1

LOV0

OMRM

* XX

ROV4

ROV3

ROV2 ROV1 ROV0 8808h

*For AC ’97 compatibility, Bit D7 is available only by setting the MSPLT bit, Register 76h. The MSPLT bit enables separate mute bits for the left and right channels.

If MSPLT is not set, Bit D7 has no effect. All registers not shown and bits containing an X are assumed to be reserved. Refer to Table IV for examples.

Note that depending on the state of the AC97NC bit in Register 76h, this register has the following additional functionality:

For AC87NC = 0, the register also controls the Surround, Center, and LFE DAC Gain/Attenuators.

For AC97NC = 1, the register controls the PCM Out Volume only.

Table IV. Volume Settings for Line-In, CD Volume, AUX, and PCM-Out

Control Bits

Reg. 76h

Line-In (10h), CD (12h), AUX (16h) and PCM-Out (18h)

Left Channel Volume D[12:8]

Right Channel Volume D[4:0]

MSPLT

*

D15 WRITE

READBACK Function

D7

* WRITE

READBACK

Function

00

0 0000

0 0000

12 dB Gain

x

0 0000

0 0000

12 dB Gain

00

0 1000

0 1000

0 dB Gain

x

0 1000

0 1000

0 dB Gain

00

1 1111

1 1111

–34.5 dB Gain

x

1 1111

1 1111

–34.5 dB Gain

01

x xxxx

x xxxx

–

dB Gain, Muted

x

x xxxx

x xxxx

–

dB Gain, Muted

10

1 1111

1 1111

–34.5 dB Gain

1

x xxxx

x xxxx

–

dB Gain,

Right Only Muted

11

x xxxx

x xxxx

–

dB Gain,

0

1 1111

1 1111

–34.5 dB Gain

Left Only Muted

11

x xxxx

x xxxx

–

dB Gain, Left Muted 1

x xxxx

x xxxx

–

dB Gain, Right Muted

*For AC ’97 compatibility, Bit D7 is only available by setting the MSPLT bit, Register 76h. The MSPLT bit enables separate mute bits for the left and right channels.

If MSPLT is not set, RM Bit has no effect.

x in the above table is “don’t care.”

Record Select Control Register (Index 1Ah)

Reg

No. Name

D15

D14

D13

D12

D11

D10

D9

D8

D7

D6

D5

D4

D3

D2

D1

D0

Default

1Ah Record Select

X

X

X

X

X

LS2

LS1

LS0

X

X

X

X

X

RS2

RS1

RS0

0000h

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

Refer to Table V for examples. Used to select the record source, independently for the right and left channels. For single MIC recording, see MS bit (Register 20h) for

MIC1 and MIC2 input selection.

For dual MIC recording, see 2CMIC bit (Register 76h) to enable simultaneous recording into the left and the right channels.

The default value is 0000h, which corresponds to MIC input for both channels.

RS [2:0]

Right Record Select

LS [2:0]

Left Record Select