Production Data

WM9704Q

WOLFSON MICROELECTRONICS LTD

PD Rev 2.3 January 2001

29

REVISION 2.1 REGISTERS (INDEX 28h T0 58h)

These registers are specified as to use in Revision 2.1 of the AC’97 specification and have the

following functions on the WM9704Q:

REGISTER 28h – EXTENDED AUDIO ID

The Extended Audio ID register is a read only register that identifies which extended audio features

are supported (in addition to the original AC’97 features identified by reading the reset register at

index 00h). A non-zero value indicates the feature is supported. The indication of support for

6-channel surround sound changes depending on whether the WM9704Q is configured in mode 00

or otherwise.

DATA BIT

FUNCTION

ANY MODE BUT 10

MODE 10

VRA

Variable rate audio support

11

DRA

Double rate audio support

00

VRM

Variable rate Mic ADC support

00

CDAC

Centre DAC support

0 (unless I

1 when ID = 11 or I

SDAC

Surround DAC support

0 (unless I

1

LDAC

LFE DAC support

0 (unless I

1 when ID = 11 or I

AMAP

Slot to front DAC mapping support

11

ID1

Codec configuration – pin 45 value

Inverse of level at pin 45

Inverse of level at pin 45

ID0

Codec configuration – pin 46 value

Inverse of level at pin 46

Inverse of level at pin 46

Table 19 Extended Audio ID Register

REGISTER 2AH - EXTENDED AUDIO STATUS AND CONTROL REGISTER

The Extended Audio Status and Control Register is a read/write register that provides status and

control of the extended audio features.

DATA BIT

FUNCTION

READ/WRITE

WM9704Q SUPPORT

VRA

Enables variable rate audio mode

Read/write

Yes

DRA

Enable double rate audio mode

Read/write

No

VRM

Enables variable rate Mic ADC

Read/write

No

CDAC

Indicates centre DAC ready

Read

Yes

SDAC

Indicates surround DAC ready

Read

Yes

LDAC

Indicates LFE DAC ready

Read

Yes

MADC

Indicates Mic ADC ready

Read

No

PRI

Set to turn off centre DAC

Read/write

Enable only

PRJ

Set to turn off surround DACs

Read/write

Enable only

PRK

Set to turn off LFE DACs

Read/write

Enable only

PRL

Set to turn off Mic ADC

Read/write

No

Table 20 Extended Audio Status and Control Register

REGISTER 2Ch TO 32h – AUDIO SAMPLE RATE CONTROL REGISTERS

These registers are read/write registers that are written to, to select alternative sample rates for the

audio PCM converters. Default is the 48ks/s rate. Note that only Revision 2.1 recommended rates

are supported by the WM9704Q, selection of any other unsupported rates will cause the rate to

default to the nearest supported rate, and the supported rate value to be latched and so read back.

Register 2Ch is the front DAC rate register, but is also used for centre channel data rate.

I