CM6502B Datasheet, PDF (29/40 Pages) C-Media Electronics – USB Audio Sound Chip

CM6502 / CM6502B
USB Audio Sound Chip
Clock
Data Signal
10011010010
Biphase Mark
Signal
1011001010110100110100
Figure -17 Biphase Mark signal of SPDIF
Preamble cell-order
cell-order
(last cell "0") (last cell "1")
------------------------------------------------------
"B"
11101000
00010111
"M"
11100010
00011101
"W"
11100100
00011011
Preamble B:
Marks a word containing data for channel A (left) at the start of the data-block.
Preamble M:
Marks a word with data for channel A that isn't at the start of the data-block.
Preamble W:
Marks a word containing data for channel B. (right, for stereo). When using more than 2 channels, this could also
be any other channel (except for A).
The number of subframes that are used depends on the number of channels that is transmitted. A CD-player
uses Channels A and B (left/right) and so each frame contains two subframes. A block contains 192 frames and
starts with a preamble "B":
Sub-frame
0
34
78
Preamble Aux Data
LSB
Audio Data
27 28 29 30 31
MSB
VUCP
V:
Valid, U:User-Data, C:Channel-Status-Data, P:Parity-Bit
Figure -1 SPDIF sub-frame description
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Rev. 1.02 ︱ Page 29