Pre-Production
WM8850
If the S/PDIF receiver unlocks and the relocks once a stream is setup, for example as a result of a
change in the rate of the S/PDIF signal applied to SPDIFIN pin, then the WM8850 can be configured
to behave in two ways:
Push Method
As soon as the S/PDIF Rx loses lock the stream is overwritten with zeros at the previously received
sample rate. Once the S/PDIF Rx achieves lock again the zeros will be removed and the recovered
samples will be output at the new sample rate. This is the default behaviour for the WM8850.
When configured for the push method it is still possible for the controller to terminate the stream while
the S/PDIF Rx is unlocked by setting the Stream ID to 0. The stream will then not be restarted until
the Stream ID has been assigned a new (non-zero) number and the S/PDIF Rx has achieved lock
again.
Controlled Method
As soon as the S/PDIF Rx loses lock the stream is overwritten with zeros at the previous received
sample rate. This will continue until the stream is terminated by the controller by setting the Stream
ID to 0, even if the S/PDIF Rx regains lock. The stream will not be restarted until the Stream ID has
been assigned a new (non-zero) number and the S/PDIF Rx has achieved lock again.
The controlled method protects against a change in the stream sample rate while the stream is active.
The S/PDIF receiver unlock behaviour is selected using the S/PDIF In Control Verb.
SET VERB
BIT
BITFIELD
NAME
DEFAULT
DESCRIPTION
7A1h
3
Unlock Ctrl
0
S/PDIF In unlock control:
0 = Push method
1 = Controlled method
As the S/PDIF In node does not support presence detect as defined in the HDA specification, by
default it will report Presence Detect Capable=0 in the Pin Capabilities Parameter. However, it is
possible to use the lock status of the S/PDIF Rx to indicate that something is plugged into S/PDIF In
using the vendor-specific S/PDIF In Control Verb. If this feature is enabled the S/PDIF In node will
report Presence Detect Capable=1 in the Pin Capabilities Parameter, will support the Pin Sense Verb
and be able to generate an unsolicited response based on the presence detect value in the Pin Sense
Verb if this functionality is set in the Unsolicited Response Verb.
SET VERB
BIT
BITFIELD
NAME
DEFAULT
DESCRIPTION
7A1h
2
PD Config
0
Configures the Presence Detect Capable
parameter:
0 = Do not use lock status as presence detect
1 = Use lock status as presence detect
PP, April 2011, Rev 3.2
59
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WOLFSON [ WOLFSON MICROELECTRONICS PLC ]
