WM9704CFTSLASHV datasheet(15/35 Pages) WOLFSON

15 / 35 page

Production Data

WM9704Q

WOLFSON MICROELECTRONICS LTD

PD Rev 2.3 January 2001

The following table shows which registers control which DAC rates, versus Mode and ID selected

MODE

FRONT DAC RATE

REAR DAC RATE

ADC RATE

REG

00 and 01

2Ch

2Eh

Rev 2.1

mode (00)

2Ch (centre) and 30h (LFE)

32h

00 and 01

2Ch

2Eh

Rev 2.1 6-

channel

mode (01)

2Ch (centre) and 30h (LFE)

32h

00 and 01

2Ch

2Eh

2Ch

Quad

mode (10)

2Ch (centre) and 30h (LFE)

2Eh

32h

Table 4 Variable Rate Register Location Versus Mode and ID

GAIN CONTROL REGISTER LOCATION VERSUS MODE AND ID

Depending on what mode and ID the device is operated in, the various gain control registers have

locations in the register map that may change. For example, if the Codec is configured as ID 10, it

means that the device will be converting the rear surround DAC data. Therefore in this case the

surround DAC volume word written to register 38h is now used to control the master volume control,

rather than the normal master volume 02h.

In addition, in this case when the surround volume mute control is written as de-mute, then mute in

the DAC PGA register 18h is automatically over-ridden, to avoid the user having to make an

unexpected additional write to register 18h to de-mute the DAC PGA.

REV 2.1 MODE (0X)

QUAD MODE (10)

PGA

CODEC

CONTROL

REG

MUTE DEFAULT

CONTROL

REG

MUTE DEFAULT

Front DAC

PGA

18h

Muted (bit15)

AND with 38h,7,15

AND with 36h,7,15

18h

Muted (bit15)

AND with 38h,7,15

AND with 36h,7,15

Rear DAC

PGA

70h

Muted (bit15)

and powered off

70h

Not-muted (bit15)

AND with 02h, 15

AND with 38h,7,15

Front Mixer

72h

Not-muted (bit15)

72h

Not-muted (bit15)

Rear Mixer

74h

Permanently muted

74h

Not-muted (bit15)

Front

Volume

02h

38h

36h

Muted (15)

muted (7 and 15)

02h

38h

36h

Muted (15)

muted (7 and 15)

Rear

Volume

04h

Muted (bit15) Rev 2.1

switch enabled

38h

02h

38h

Muted (7 and 15)

muted (15)

muted (7 and 15)

Table 5 Gain Control Register Location Versus Mode and ID

MASTER/SLAVE ID0/1 SUPPORT

WM9704Q supports operation as either a master or a slave codec. Configuration of the device as

either a master or as a slave, is selected by tying the ID pins CID0 and CID1, pins 45 and 46 on the

package.

Fundamentally, a device identified as a master (ID = 00) produces BITCLK as an output, whereas a

slave (any other ID) must be provided with BITCLK as an input. This has the obvious implication that

if the master device on an AC link is disabled, the slave devices cannot function.

The AC’97 Revision 2.1 specification defines that the ID pins have inverting sense, and are provided

with internal weak pull ups. Therefore, if no connections are made to the CID0/1 pins, then the pins

pull hi and an ID = 00 is selected, i.e. master. External connects to ground will select other IDs.

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