ADSP-214xx SHARC Processor Hardware Reference 8-7
Media Local Bus
fashion, receiving devices cannot return a busy status and should not drive
RxStatus onto the
MLBSIG line.
For further information on the MediaLB Specification, please refer to the
MediaLB specification document available on www.smsc-ais.com.
Operating Modes
The following sections describe the operating modes of the MLB
interface.
Streaming Channel Frame Synchronization
Certain types of streaming applications require data to be synchronous
with the MediaLB frame, including: stereo, 5.1 audio, and Generic Syn-
chronous Packet Format (GSPF) DTCP. This feature is provided as an
optional programmable synchronous logical channel by setting the FSE bit
in the MLB_CECRx register. When enabled, the synchronous logical channel
begins transmitting data only at a MediaLB frame boundary. A maskable
interrupt is generated when the loss of frame synchronization occurs.
In order to use this option, system software must program the FSPC bits in
the MLB_CECRx register with the expected number of physical channels per
frame for the logical channel, and unmask the
STS interrupt bit (bit 6) in
the MLB_CSCRx register by setting the MASK bit in MLB_CECRx register. An
interrupt is generated when the actual number of physical channels
detected during a MLB frame does not match the expected value. Software
can also set the
FSCD bit in MLB_CSCRx register, which causes hardware to
automatically disable a logical channel (clear the channel enable bit in the
MLB_CECRx register) when synchronization is lost.
Frame synchronization is not supported for asynchronous, control or iso-
chronous channels.
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