Production Data

WM9704M

WOLFSON MICROELECTRONICS LTD

PD Rev 3.2 January 2001

29

POWERDOWN CONTROL/STATUS REGISTER (INDEX 26H)

Note that in order to go into ultimate low power mode, PR5 is required to be set which turns

off the oscillator circuit. Asserting SYNC resets the PR5 bit and re-starts the oscillator in the

same was as the AC link is restarted.

Also when RESETB pin is asserted low, all PR bits are over-ridden and the entire device is

powered off to ultra low power state for as long as RESETB = low. On releasing RESETB,

the device is reset (all active) and powered up.

REV 2.1 REGISTERS (INDEX 28H T0 58H)

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

functions on the WM9704M:

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.

DATA BIT

FUNCTION

VALUE

VRA

Variable rate audio support

1

DRA

Double rate audio support

0

VRM

Variable rate Mic ADC support

0

CDAC

Centre DAC support

0

SDAC

Surround DAC support

0 (unless I

LDAC

LFE DAC support

0 (unless I

AMAP

Slot to front DAC mapping support

1

ID1

Codec configuration – pin 45 value

Inverse of level at pin 45

ID0

Codec configuration – pin 46 value

Inverse of level at pin 46

Table 18 Extended Audio Capability 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

WM9704M 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 19 Extended Audio Status and Control Register