WM9707

Advanced Information

WOLFSON MICROELECTRONICS LTD

AI Rev 2.2 January 2001

26

VENDOR SPECIFIC GAIN CONTROL REGISTERS – (INDEX 72h)

This register controls the gain and mute functions applied to the mixer path. This PGA is not

accommodated in the Intel specification, but is required in order to allow the option of simultaneous

recording of the mixer output and playback of DAC signals. The function is as per the other mixer

PGA’s. However, the default value of the register is not-muted. If it is not used it will be transparent to

the user.

VENDOR ID REGISTERS (INDEX 7Ch TO 7Eh)

This register is for specific vendor identification if so desired. The ID method is Microsoft’s Plug and

Play Vendor ID code. The first character of that ID is F7 to F0, the second character S7 to S0, and

the third T7 to T0. These three characters are ASCII encoded. The REV7 to REV0 field is for the

Vendor Revision number. In the WM9707 the vendor ID is set to WML3.

Wolfson is a registered Microsoft Plug and Play vendor.

VENDOR ID REGISTERS (INDEX 74h)

This register describes how data is mapped to the AC’97 DACs. Register 74h can be used to change

the incoming DAC data slots that are used by the on-board DACs. This allows software control of

multiple codecs.

SURROUND SOUND

DSS1, DSS0

PCM OUT LEFT

PCM OUT RIGHT

00

3

4

01

7

8

1X

6

9

Table 15 Vendor ID Registers - Reg 74 [1:0]

SURROUND SOUND

ASS1, ASS0

PCM IN LEFT

PCM IN RIGHT

00

3

4

01

7

8

1X

6

9

Table 16 Vendor ID Registers – Reg 74 [9:8]

This register describes how data is mapped onto the AC-link. Register 74h can be used to map ADC

data onto multiple AC-link slots under software control.

This allows the user to connect multiple codecs to a host controller using a single AC-link interface.

The volume control register is still 02h and the rate register is 2Ch. The ID pins have no effect on this

mapping.