alc885-gr Realtek Semiconductor Corporation, alc885-gr Datasheet - Page 20

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alc885-gr

Manufacturer Part Number
alc885-gr
Description
7.1+2 Channel High-performance Hda Codec With Content Protection
Manufacturer
Realtek Semiconductor Corporation
Datasheet
7.2. Frame Composition
7.2.1.
An outbound frame is composed of one 32-bit command stream and multiple data streams. There are one
or multiple sample blocks in a data stream. Only one sample block exists in a stream if the HDA
controller delivers a 48kHz rate of samples to the codec. Multiple sample blocks in a stream means the
sample rate is a multiple of 48kHz. This means there should be two blocks in the same stream to carry
96kHz samples (Figure 7).
For outbound frames, the stream tag is not in SDO, but in the SYNC signal. A new data stream is started
at the end of the stream tag. The stream tag includes a 4-bit preamble and 4-bit stream ID (Figure 8).
To keep the cadence of converters bound to the same stream, samples for these converters must be placed
in the same block.
7.1+2 Channel High-Performance HDA Codec
With Content Protection
SYNC
Previous Frame
SDO
Frame SYNC
Outbound Frame – Single SDO
Sample 1 Sample 2
Block 1
Command Stream
Sample Block(s)
msb
A 48kHz Frame is composed of Command stream and multiple Data streams
Block 2
SYNC
BCLK
SDO
...
lsb
Figure 8.
..
..
.
.
msb first in a sample
Previous Stream
Stream 'A' Data
Figure 7.
Stream 'A' Tag
(Here 'A' = 5)
One or multiple blocks in a stream
Preamble Stream=10
Sample Z
Block Y
(4-Bit)
7 6 5 4
SDO Stream Tag is Indicated in SYNC
Stream Tag
msb
1
For 96kHz rate, Block1 includes (N)
includes (N+1)
3
For 48kHz rate, only Block1 is included
Z channels of PCM Sample
SDO Outbound Frame
(4-Bit)
0
2
lsb
1 0
1
12
0
Data of Stream 10
th
time of samples
Stream 'X' Tag
(Here 'X' = 6)
Stream 'X' Data
Null Field
th
time of samples, Block2
0s
ALC885 Series
Padded at the
end of Frame
Next Frame
Datasheet
Rev. 1.1