wm9704q Wolfson Microelectronics plc, wm9704q Datasheet - Page 17

• Manufacturer Part Number: wm9704q
• Description: 4-channel Surround Sound Codec
• Manufacturer: Wolfson Microelectronics plc

Production Data
CONTROL INTERFACE
AC-LINK DIGITAL SERIAL INTERFACE PROTOCOL
WOLFSON MICROELECTRONICS LTD
Table 9 Slave Codec Register Access Slot 0-Bit Definitions
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:
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.
Figure 8 AC’97 Standard Bi-directional Audio Frame
OUTPUT TAG SLOT (16-BITS)
New definitions for Slave Codec Register Access
SDATA_OUT
SDATA_IN
NUMBER
12-3
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.
BIT
1-0
15
14
13
2
SYNC
SLOT
CODEC ID
SLOTREQ 3-12
TAG
TAG
DESCRIPTION
Frame Valid
Slot 1 Valid Command Address Bit (Master Codec only)
Slot 2 Valid Command Data Bit (Master Codec only)
Slot 3-12 Valid Bits as defined by AC’97
Reserved (Set to 0)
2-bit Codec ID field (00 reserved for Master; 01, 10, 11 indicate Slave)
0
STATUS
ADDR
CMD
ADR
1
STATUS
DATA
DATA
CMD
2
LEFT
LEFT
PCM
PCM
3
RIGHT
RIGHT
PCM
PCM
4
LINE 1
LINE 1
DAC
ADC
5
CENTRE
PCM
ADC
MIC
6
L SURR
RSRVD
PCM
7
R SURR
RSRVD
PCM
8
RSRVD
PCM
LFE
9
LINE 2
LINE 2
PCM L
(n+1)
PD Rev 2.3 January 2001
DAC
ADC
10
PCM R
WM9704Q
HSET
HSET
(n+1)
DAC
ADC
11
STATUS
PCM C
CTRL
(n+1)
12
IO
IO
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