ADAV803 Analog Devices, ADAV803 Datasheet - Page 24

• Manufacturer Part Number: ADAV803
• Description: Audio Codec
• Manufacturer: Analog Devices

ADAV803
Seria
The
IEC-
and AES
both con
not in
standa
for th
All thes
data and
metho
transm
origin
mark
that th
betwe
Digital audio-communication schemes use preambles to
distinguish among channels (called subframes) and among
longer-term control information blocks (called frames).
Preambles are particular biphase-mark patterns, which contain
encoding violations that allow the receiver to uniquely
recognize them. These patterns and their relationship to frames
and subframes are shown in Table 8 and Figure 44.
Table 8. Biphase-Mark Encode Preamble
X
Y
Z
(2 TIMES BIT RATE)
BIPHASE-MARK
ADAV803 can receive and tra
958 serial str
Biphase Patterns
11100010 or 00011101
11100100 or 00011011
11101000 or 00010111
e full specification
l Dig
tended to f
encoded data, while 0s in
en bit bounda
al data end up with m
rds. Con
d. This encoding me
e biphase-mark encod
itted signal. As c
e digita
/EBU is a profe
sumer and pro
audio control info
CLOCK
ital A
DATA
DATA
6.8nF
tact the international standards-setting bodies
l audio communication schemes encode audio
Figure 42.
AVDD
ully define or to provide a tutorial for thes
udio
eams. SPDIF is a consumer audio standar
Figure 43. Biphase-Mark Encoding
ries.
0
Transmission S
an be seen from Figure 43, 1s
fessional definitions. This da
ssional audio standard. IEC-
s.
3Ω
1
DIR Loop Filter Comp
00µ
thod minimizes the dc
rmation using the biphas
idcell transitions in th
F
1
ed
DIR_LF
the original da
data always ha
DIR BLOCK
nsmit S
1
Channel
Left
Right
Left and CS block start
tand
1
PDIF, AES/EBU
one
ards
nts
ta do not. Note
s
0
a transition
e biphase-
content of the
958 has
ta sheet is
e-mark
in the
0
, and
e
d,
Rev. 0 | Page 24 of 56
The biphase-mark encoding violations are shown in Figure 45.
Note that all three pr eambles include encoding violations.
Ordinarily, the biphase-mark encoding method results in a
polarity transition between bit boundaries.
The serial digital audio communication scheme is organized
using a frame and subframe construction. There are two
subframes per frame (ordinarily the left and right channel).
Each subframe includes the appropriate 4-bit preamble, up
24 bits of audio data, a validity (V) bit, a user (U) bit, a channel
status (C) bit, and an even parity (P) bit. The channel status bits
and the user bits accumulate over many frames to convey
control information. The channel status bits accumulate over a
192 frame period (called a channel status block). The user bits
accumulate over 1,176 frames when the interconnect is imple-
menting the so-called subcode scheme
organization of the channel status block, frames, and subframe
is shown in Table 9 and Table 10. Note that the ADAV803
supports the profess
point of view only. The digital interface supports only
c
Table 9. Consumer Audio Standard
Address
N
N + 1
N + 2
N + 3
N + 4
N + 5 to
(N + 23)
N =
N =
onsumer mode.
X
0x20 fo
0x38 for transmitte
LEFT CH
FRAME 191
PREAMBLE X
PREAMBLE Y
PREAMBLE Z
r re
7
Y
ceiver ch
RIGHT CH
Reserved
Figure 44. Preambles, Frames, and Subframes
C
Status
hannel
Channel Number
r channel status buffer.
annel status buffer.
6
Reserved
ional audio standard from a software
Z
FRAME
LEFT CH
1
1
1
SUB-
Figure 45. Preambles
PREAMBLES
5
1
1
1
FRAME 0
Accuracy
Clock
Emphasis
Y
1
1
1
RIGHT CH
Category Code
FRAME
4
SUB-
0
0
0
Data Bits
Reserved
0
0
1
(EIAJ CP-2401). The
3
X
0
1
0
LEFT CH
Sampling Frequency
1
0
0
Copy-
right
Source Number
FRAME 1
Word Length
2
0
0
0
Y
RIGHT CH
Audi
Non-
1
o
to
Pro/
Con
= 0
0
s