wm9708 Wolfson Microelectronics plc, wm9708 Datasheet - Page 15

• Manufacturer Part Number: wm9708
• Description: Ac?97 Revision 2.1 Audio Codec
• Manufacturer: Wolfson Microelectronics plc

Production Data
AC-LINK DIGITAL SERIAL INTERFACE PROTOCOL
Figure 8 AC’97 Standard Bi-directional Audio Frame
Figure 9 AC-link Audio Output Frame
w
SDATAOUT
TAG PHASE
SDATAOUT
NUMBER
BITCLK
SLOT
SYNC
SYNC
END OF PREVIOUS
AUDIO FRAME
CODEC ID
SLOTREQ 3-12
TAG
TAG
0
FRAME
VALID
12.288MHz
STATUS
TAG PHASE
SLOT(1)
ADDR
CMD
ADR
The WM9708 incorporates a 5-pin digital serial interface that links it to the AC’97 controller. The 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 and a 16-bit header slot. 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 WM9708 provides support for 18-bit
operation.
1
SLOT(2)
('1' = TIME SLOT CONTAINS
81.4nS
TIME SLOT 'VALID' BITS
STATUS
DATA
DATA
CMD
VALID PCM DATA)
2
SLOT(12)
LEFT
LEFT
PCM
PCM
3
'0'
RIGHT
RIGHT
(ID1)
PCM
PCM
4
(ID0)
RSRVD
RSRVD
5
19
SLOT (1)
DATA PHASE
CENTRE
RSRVD
PCM
6
0
L SURR
RSRVD
PCM
19
20.8μS (48kHz)
DATA PHASE
7
SLOT (2)
R SURR
RSRVD
PCM
8
0
19
RSRVD
PCM
LFE
SLOT (3)
9
RSRVD
RSRVD
PCM L
(n+1)
10
0
PD, Rev 4.2, August 2009
RSRVD
RSRVD
PCM R
(n+1)
11
19
SLOT (12)
RSRVD
RSRVD
PCM C
(n+1)
12
WM9708
0
15