SAA7335 Datasheet, PDF (17/36 Pages) NXP Semiconductors – DSP for CD and DVD-ROM systems

Philips Semiconductors
DSP for CD and DVD-ROM systems
Preliminary specification
SAA7335
handbook, full pagewidth
BCLK
DATA
FLAG
WCLK
SYNC
D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0
flag-MSB (1 is unreliable)
left
flag-LSB
variable number of clocks
D15 D14
flag-MSB
right
MGK251
Fig.12 Philips I²S-bus data format (variable word length).
EBU interface
The biphase-mark digital output signal at pin DOBM is in
accordance with the format defined by the “IEC 958”
specification.
Three different modes can be selected via the EBU output
control register (address 1010).
FORMAT
The digital audio output consists of 32-bit words
(subframes) transmitted in biphase-mark code
(2 transitions for a logic 1 and one transition for a logic 0).
Words are transmitted in blocks of 384 (see Table 4).
AUDIO SAMPLE
Left and right samples are transmitted alternately.
VALIDITY FLAG
Audio samples are flagged (bit 28 = logic 1) if an error has
been detected but was non-correctable. This flag remains
the same even if data is taken after concealment.
USER DATA
Subcode bits Q-to-W from the subcode section are
transmitted via the user data bit. This data is asynchronous
with the block rate.
SYNC
The sync word is formed by violation of the biphase rule
and therefore does not contain any data. Its length is
equivalent to 4 data bits. The three different sync patterns
indicate the following situations:
• Sync B: start of a block (384 words), word contains left
sample
• Sync M: word contains left sample (no block start)
• Sync W: word contains right sample.
CHANNEL STATUS
The channel status bit is the same for left and right words.
Therefore a block of 384 words contains 192 channel
status bits. The category code is always CD. The bit
assignment is given in Table 5.
1997 Aug 11
17