Production Data

WM9704Q

WOLFSON MICROELECTRONICS LTD

PD Rev 2.3 January 2001

17

OUTPUT TAG SLOT (16-BITS)

BIT

DESCRIPTION

15

Frame Valid

14

Slot 1 Valid Command Address Bit (Master Codec only)

13

Slot 2 Valid Command Data Bit (Master Codec only)

12-3

Slot 3-12 Valid Bits as defined by AC’97

2

Reserved (Set to 0)

1-0

2-bit Codec ID field (00 reserved for Master; 01, 10, 11 indicate Slave)

New definitions for Slave Codec Register Access

Table 9 Slave Codec Register Access Slot 0-Bit Definitions

CONTROL INTERFACE

A digital interface has been provided to control the WM9704Q and transfer data to and from it. This

serial interface is compatible with the Intel AC’97 specification as illustrated in Figure 7.

The main control interface functions are:

•

Control of analogue gain and signal paths through the mixer.

•

Bi-directional transfer of ADC and DAC words to and from AC’97 controller.

•

Selection of powerdown modes.

AC-LINK DIGITAL SERIAL INTERFACE PROTOCOL

The WM9704Q incorporates a 5-pin digital serial interface that links it to the AC’97 controller. AC-link

is a bi-directional, fixed rate, serial PCM digital stream. It handles multiple input and output audio

streams, as well as control register accesses employing a time division multiplexed (TDM) scheme.

The AC-link architecture divides each audio frame into 12 outgoing and 12 incoming data streams,

each with 20-bit sample resolution. With a minimum required DAC and ADC resolution of 16-bits,

AC’97 may also be implemented with 18 or 20-bit DAC/ADC resolution, given the headroom that the

AC-link architecture provides. The WM9704Q provides support for 18-bit operation.

SLOT

NUMBER

SYNC

SDATA_OUT

SDATA_IN

TAG

CMD

ADR

CMD

DATA

PCM

LEFT

PCM

RIGHT

LINE 1

DAC

PCM

LFE

LINE 2

DAC

HSET

DAC

TAG

STATUS

ADDR

STATUS

DATA

PCM

LEFT

PCM

RIGHT

LINE 1

ADC

MIC

ADC

RSRVD

RSRVD

RSRVD

LINE 2

ADC

HSET

ADC

IO

STATUS

012

3

456789

10

11

12

PCM

CENTRE

PCM

L SURR

PCM

R SURR

IO

CTRL

PCM C

(n+1)

PCM R

(n+1)

PCM L

(n+1)

CODEC ID

SLOTREQ 3-12

Figure 8 AC’97 Standard Bi-directional Audio Frame