datasheetbank_Logo
Integrated circuits, Transistor, Semiconductors Search and Datasheet PDF Download Site

WM8860 View Datasheet(PDF) - Wolfson Microelectronics plc

Part Name
Description
View to exact match
WM8860
Wolfson
Wolfson Microelectronics plc Wolfson
WM8860 Datasheet PDF : 184 Pages
First Prev 21 22 23 24 25 26 27 28 29 30 Next Last
WM8860
Pre-Production
In D3 (with the link is the Link Reset state), the WM8860 is capable of generating a wake (i.e. a power
state change request). The Controller will respond to the wake by putting the WM8860 through an
initialisation sequence. The initialisation sequence will not change the register settings, so the
WM8860 will still report a power state of D3 but the WM8860 will be able to send responses, including
any unsolicited response(s) that caused a wake to be issued.
As register settings are maintained in the D3/D4 states, the user should be aware that if the WM8860
is brought from D3/D4 to D0 and stream IDs had been previously assigned, data rendering and
capture will commence. If this behaviour is not desired, the user should bring the WM8860 to state
D3 and set the stream IDs to 0, or ensure that stream IDs are set to 0 prior to entering the D3/D4
state.
STREAM START/STOP
Sections 4.5.3 and 4.5.4 of the Intel HD Audio specification describe the starting and stopping of
streams. While the descriptions are sufficient from a controller perspective, there are ambiguities from
a CODEC perspective.
For each stream that goes through the HDA Link, there is a ‘Stream Manager’ module within the
WM8860 whose function is to assemble/disassemble the stream packets within the link frame. The
Stream Manager is disabled while the Stream value in the Converter Stream, Channel Verb is set to
0h. When disabled, the captured data will not be sent on the link, and data from the link will not be
decoded for rendering.
For audio path configuration, it is assumed that the Stream ID is the last register to be set in the
configuration sequence. When Stream ID is set to a non-zero value it has the effect of starting the
stream. On starting the stream, Stream Managers associated with input converters begin transmitting
data on the link, and Stream Managers associated with output converters begin to decode data with
the corresponding stream tag.
Note: Audio paths with mute capabilities may have ‘un-mute’ as the final configuration step. For
these paths, the stream will have started but the audio data will be zeroed until mute has been
disabled.
There are test paths within the WM8860 that do not use the HDA Link. These paths can still be used
when the Stream Manager is disabled.
The Stream Manager is also disabled when the associated converter widget is in power state D1, D2
or D3. Digital converters (i.e. S/PDIF) have a DigEn register bit. When this is set to 0, the associated
stream manager is disabled.
It is assumed that the settings of the Stream Format Verb and Converter Stream, Channel Verb will
not change when a stream is active (with the exception of changing the Stream ID to 0 to terminate
the stream). Changing stream settings while a stream is active is an erroneous action, and may
result in audio corruption.
SDI STREAM ORDER
The order of stream transmission on the SDI link is governed by the CODEC. The WM8860 will
transmit streams with the lowest stream ID value first.
If a stream is started with a stream ID lower than an existing stream, then the new stream is
transmitted earlier in the frame than the existing stream (i.e. the WM8860 auto-shuffles the stream
placement within the frame). This moves the existing stream to further on in the frame than it was
prior to the starting of the new stream. It is assumed that moving streams within a frame is
acceptable to the Controller.
BANDWIDTH CONFLICTS
Sections 5.3.2.2 and 5.3.3.3 of the HD Audio spec describe the scenario of over-subscription of SDO
and SDI bandwidths. It indicates that the final stream on the link is terminated prior to completion, and
further behaviour is undefined.
w
PP, April 2011, Rev 3.2
28
 

Share Link: 

datasheetbank.com [ Privacy Policy ] [ Request Datasheet ] [ Contact Us ]