wm8802scft/v Wolfgang Knap, wm8802scft/v Datasheet - Page 32

• Manufacturer Part Number: wm8802scft/v
• Description: Digital Audio Interface Transceiver
• Manufacturer: Wolfgang Knap

WM8802
IEC61937, DTS-CD/LD DETECTION FLAG OUTPUT
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A function to output IEC61937 and DTS-CD/LD detection flags for non-PCM data is provided.
When the UNPCM non-PCM signal output setting is selected, as well as an indication on the AUDIO
pin, an interrupt signal is output from INT upon detection of an IEC61937 or DTS-CD/LD sync signal.
Non-PCM signal details can be known by reading this information from the output register.
The IEC61937 sync signal is detected and output when channel status bit 1 is non-PCM data ("1").
The IEC61937 sync signal is not output if bit 1 is PCM data (“0”).
DTS-CD/LD sync signal detection is done based on the sync pattern and the base frequency. In the
case of DTS-ES data detection, output is performed when the DTS5.1 channel sync signal is
detected and the DTS-ES sync pattern has been verified.
The IEC61937 and DTS-CD/LD detection flags are cleared when fs has changed or upon occurrence
of a PLL lock error or data error.
Since the DTS sync signal is provided within the audio data, digital data with the same code as the
DTS sync signal may in rare cases exist for regular CD/LD records that are not recorded in the DTS
format. Protection using the sync pattern or base frequency is provided so that such data is not
misinterpreted as DTS-CD/LD detection flags. The detection sequence is shown below.
Figure 24 Detection Flag Output Flowchart
IEC61937 flag OK
Frame counter
Bit 1 detection
IEC61937 data
during 4096
during 4096
INT lowered
detection
Input data
detection
YES
detection
YES
Bit 1 = 1
YES
YES
frames
frames
PaPb
PaPb
start
PaPb
hold
NO
NO
NO
NO
*
1st count
Depending on the frame count,
the subsequent detection count
is expanded up to x2.
Periodic fluctuation is supported.
Frame counter
1024
2048
4096
512
IEC61937
reset
flag
=> 512 or 1024
=> 1024 or 2048
=> 2048 or 4096
=> 4096
2nd count
*
*
512, 1024, 2048, 4096
512, 1024, 2048, 4096
DTS-CD/LD flag OK
x2 count detection
Frame count hold
SYNC detection
SYNC detection
Frame counter
Frame count
Frame count
INT lowered
DTS-CD/LD
DTS-CD/LD
expansion
data hold
detection
YES
YES
YES
SYNC
start
NO
NO
NO
DTS-CD/LD flag
Frame counter
INT lowered
not valid
PP Rev 1.1 April 2004
reset
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