REV. 0

–18–

AD1980

NORMAL

ADCs OFF

PR0

DACs OFF

PR1

ANALOG

OFF

PR2 OR

PR3

DIGITAL I/F

OFF

PR4

SHUT OFF

AC-LINK

PR0 = 1

PR1 = 1

PR2 = 1

PR4 = 1

DEFAULT

PR0 = 0

AND

ADC = 1

PR1 = 0

AND

DAC = 1

PR2 = 0

AND

ANL = 1

WARM

RESET

COLD

RESET

READY = 1

Figure 8. One Example of AC ‘97 Power-Down/Power-Up Flow

Extended Audio ID Register (Index 28h)

Reg

No. Name

D15 D14 D13 D12 D11

D10

D9

D8

D7

D6

D5

D4

D3

D2

D1

D0

Default

28h Ext’d Audio

ID1

ID0

X

X

REV1 REV0 AMAP LDAC

SDAC

CDAC

DSA1

DSA0

X

SPDIF DRA VRA

X3C7h

The extended audio ID register identifies which extended audio features are supported. A nonzero extended audio ID value indicates one or more of the extended

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

VRA

Variable Rate PCM Audio Support (Read Only).

This bit returns a “1” when read to indicate that the Variable Rate PCM Audio is supported.

DRA

Double Rate Audio (Read Only).

This bit returns a “1” when read to indicate that the optional Double Rate RCM Audio is supported for PCM L

and PCM R.

SPDIF

SPDIF Support (Read Only). This bit returns a “1” when read to indicate that the SPDIF transmitter is supported

(IEC958).

This bit is also used to validate that the SPDIF transmitter output is actually enabled. The SPDIF bit is only

allowed to be set high if the SPDIF pin (48) is pulled down at power-up, enabling the codec transmitter logic. If the

SPDIF pin is floating or pulled high at power-up, the transmitter logic is disabled and therefore this bit returns a

low, indicating that the SPDIF transmitter is not available. This bit must always be read back to verify that the

SPDIF transmitter is actually enabled.

DSA[1,0]

DAC Slot Assignments (Read/Write) (Reset Default = 00)

00

DACs 1, 2 = 3 and 4

DACs 3, 4 = 7 and 8

DACs 5, 6 = 6 and 9

01

DACs 1, 2 = 7 and 8

DACs 3, 4 = 6 and 9

DACs 5, 6 = disabled

10

DACs 1, 2 = 6 and 9

DACs 3, 4 = disabled

DACs 5, 6 = disabled

11

Reserved

CDAC

PCM CENTER DAC Support (Read Only).

This bit returns a “1” when read to indicate that PCM center DAC is supported.

SDAC

PCM Surround DAC Support (Read Only).

This bit returns a “1” when read to indicate that PCM surround left and right DACs are supported.

LDAC

PCM LFE DAC Support (Read Only),

This bit returns a “1” when read to indicate that PCM LFE DAC is supported.

AMAP

Slot DAC Mappings Based on Codec ID (Read Only).

This bit returns a “1” when read to indicate that slot/DAC mappings based on codec ID are supported.

REV[1,0]

REV[1,0] = 01 indicates codec is AC ’97 revision 2.2 compliant (Read Only).

ID[1:0]

Indicates Codec Configuration (Read Only).

00 = Primary

01, 10, 11 = Secondary