Advanced Information
WM9707
SLOTS 6 TO 9: SURROUND SOUND DATA
Audio output frame slots 6 to 9 are used to send surround sound data.
SLOTS 10 AND 11: LINE2 AND HANDSET DAC
These data slots are not supported.
SLOT 12: GPIO CONTROL
These data slots are not supported.
AC-LINK AUDIO INPUT FRAME (SDATA_IN)
TAG PHASE
DATA PHASE
20.8µS (48kHz)
SYNC
12.288MHz
81.4nS
BIT_CLK
CODEC
READY
SLOT(1) SLOT(2)
SLOT(12)
’0’
’0’
’0’
19
0
19
0
19
0
19
SLOT (12)
0
SDATA_IN
TIME SLOT ’VALID’ BITS
(’1’ = TIME SLOT CONTAINS
VALID PCM DATA)
SLOT (1)
SLOT (2)
SLOT (3)
END OF PREVIOUS
AUDIO FRAME
Figure 13 AC-link Audio Input Frame
The audio input frame data streams correspond to the multiplexed bundles of all digital input data
targeting the AC’97 controller. As is the case for audio output frame, each AC-link audio input frame
consists of 12, 20-bit time slots.
Slot 0 is a special reserved time slot containing 16-bits, which are used for AC-link protocol
infrastructure.
Within slot 0 the first bit is a global bit (SDATA_IN slot 0, bit 15) which flags whether the WM9707 is
in the Codec Ready state or not. If the Codec Ready bit is a 0, this indicates that the WM9707 is not
ready for normal operation. This condition is normal following the desertion of power on reset for
example, while the WM9707’s voltage references settle. When the AC-link Codec Ready indicator bit
is a 1, it indicates that the AC-link and the WM9707 control and status registers are in a fully
operational state. The AC’97 controller must further probe the Powerdown Control/Status Register to
determine exactly which subsections, if any, are ready.
Prior to any attempts at putting the WM9707 into operation the AC’97 controller should poll the first
bit in the audio input frame (SDATA_IN slot 0, bit 15) for an indication that the WM9707 has gone
Codec Ready.
Once the WM9707 is sampled Codec Ready then the next 12 bit positions sampled by the AC’97
controller indicate which of the corresponding 12 time slots are assigned to input data streams, and
that they contain valid data. Figure 13 illustrates the time slot based AC-link protocol.
There are several subsections within the WM9707 that can independently go busy/ready. It is the
responsibility of the WM9707 controller to probe more deeply into the WM9707 register file to
determine which the WM9707 subsections are actually ready.
WOLFSON MICROELECTRONICS LTD
AI Rev 2.2 January 2001
17
WOLFSON [ WOLFSON MICROELECTRONICS PLC ]
