Advanced Information
WM9707
PIN 45 CID
ID
MASTER OR
SLAVE
BITCLK
SELECTED
NC
0
1
Master
Slave
Output
Input
Ground
Table 3 ID Selection
CONTROL INTERFACE
A digital interface has been provided to control the WM9707 and transfer data to and from it. This
serial interface is compatible with the Intel AC’97.
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 down modes.
AC-LINK DIGITAL SERIAL INTERFACE PROTOCOL
The WM9707 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 WM9707 provides support for 18-bit operation.
SLOT
NUMBER
0
1
2
3
4
5
6
7
8
9
10
11
12
SYNC
SDATA_OUT
SDATA_IN
PCM
CENTRE
PCM
L SURR
PCM
R SURR
PCM
LFE
CMD
ADR
CMD
DATA
PCM
LEFT
PCM
RIGHT
TAG
RSRVD
RSRVD
RSRVD
RSRVD
RSRVD
PCM L
(n+1)
PCM R
(n+1)
PCM C
(n+1)
CODEC ID
STATUS
ADDR
STATUS
DATA
PCM
LEFT
PCM
RIGHT
RSRVD
TAG
RSRVD
RSRVD
RSRVD
RSRVD
RSRVD
RSRVD
SLOTREQ 3-12
DATA PHASE
TAG PHASE
Figure 10 AC’97 Standard Bi-directional Audio Frame
WOLFSON MICROELECTRONICS LTD
AI Rev 2.2 January 2001
13
WOLFSON [ WOLFSON MICROELECTRONICS PLC ]
