CS4297A_06 Datasheet, PDF (18/52 Pages) Cirrus Logic – CrystalClear® SoundFusion™ Audio Codec ‘97

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3.3 AC-Link Protocol Violation - Loss of
SYNC
The CS4297A is designed to handle SYNC proto-
col violations. The following are situations where
the SYNC protocol has been violated:
• The SYNC signal is not sampled high for exact-
ly 16 BIT_CLK clock cycles at the start of an
audio frame.
• The SYNC signal is not sampled high on the
256th BIT_CLK clock period after the previous
SYNC assertion.
• The SYNC signal goes active high before the
256th BIT_CLK clock period after the previous
SYNC assertion.
Upon loss of synchronization with the controller,
the CS4297A will ‘clear’ the Codec Ready bit in
the serial data input frame until two valid frames
are detected. During this detection period, the
CS4297A will ignore all register reads and writes
and will discontinue the transmission of PCM cap-
ture data. In addition, if the LOSM bit in the Misc.
Crystal Control Register (Index 60h) is ‘set’ (de-
fault), the CS4297A will mute all analog outputs. If
the LOSM bit is ‘clear’, the analog outputs will not
be muted.
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