CS8401A-CS Ver la hoja de datos (PDF) - Cirrus Logic
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CS8401A-CS Datasheet PDF : 34 Pages
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CS8402A
C, U, V Serial Port
The serial input pins for channel status (C), user
(U), and validity (V) are sampled during the first
bit period after the active edge of FSYNC for all
formats except Format 4, which is sampled dur-
ing the second bit period (coincident with the
MSB). In Figure 16, the arrows on SCK indicate
when the C, U, and V bits are sampled. The C,
U, and V bits are transmitted with the audio
sample entered before the FSYNC edge that
sampled it. The V bit, as defined in the audio
standards, is set to zero to indicate the audio data
is suitable for conversion to analog. Therefore,
when the audio data is errorred, or the data is
not audio, the V bit should be set high. The
channel status serial input pin (C) is not avail-
able in consumer mode when the CD subcode
port is enabled (FC1 = FC0 = high). Any chan-
nel status data entered through the channel status
serial input (C) is logically OR’ed with the data
entered through the dedicated pins or internally
generated.
TRNPT high
CBL
TRNPT low
RST and CBL (TRNPT is low)
When RST goes low, the differential line drivers
are set to ground and the block counters are reset
to the beginning of the first block. In order to
properly synchronize the CS8402A to the audio
serial port, the transmit timing counters, which
include CBL, are not enabled after RST goes
high until eight and one half SCK periods after
the active edge (first edge after reset is exited) of
FSYNC. When FSYNC is configured as a
left/right signal (all defined formats except 2),
the counters and CBL are not enabled until the
right sample is being entered (during which the
previous left sample is being transmitted). This
guarantees that channel A is left and channel B
is right as per the digital audio interface specs.
As shown in Figure 17, CBL, channel block start
output, can assist in serially inputting the C, U
and V bits as CBL goes high one bit period be-
fore the first bit of the preamble of the first
sub-frame of the channel status block is trans-
SDATA
FSYNC
TRNPT high
C,U,V
TRNPT low
TXP
TXN
Left 0
Right 0
Left 1
Left 128
Right 128
Left 0
Right 0
CUV0L
C bits from Cpin
CUV0R
CUVIL
CUV1R
CUV128R
CUV0L
CUV0R
CUV191R
C bits OR'ed w/
PRO pin
CUV0L
CUV0R
C bit OR'ed w/
C1 pin
Right 191
VUCP191R
Preamble Y
Left 0
VUCP0L
Preamble Z
Right 0
VUCP0R
Preamble Y
CUV1L
CUV128L
Bit 0 of C.S.
Block Byte 16
VUCP127R
Left 128
VUCP128L
Preamble X
CUV191R
Right 128
Preamble Y
CUV0L
bit 0
34
78
Preamble Z
Aux Data
LSB
Left 0 - Audio Data
Sub-frame
Figure 17. CBL and Transmitter Timing
20
27 28 29 30 31
MSB V0 U0 C0 P0
DS60F1
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