CS4207 Datasheet, PDF (137/144 Pages) Cirrus Logic – Low-power, 4-in / 6-out HD Audio CODEC with Headphone Amp

7. APPLICATIONS
CS4207
7.1 HD Audio Interface
7.1.1 Multi-Channel Streams
The CS4207 codec supports multi-channel streams (streams with sample blocks containing more than
two samples), on both inbound and outbound frames. Each of the 5 output converter widgets (DAC1/2/3,
S/PDIF TX 1/2) can be associated with an individual stream, or multiple widgets can be grouped to share
the same stream. A mix of shared and individual streams is also supported. Furthermore, the order in
which channels are assigned to each widget is not constrained by design. However, the following limita-
tions exist and must be avoided:
• a stream cannot contain channels that are not associated with any widget (unused channels), unless
those channels appear last within the stream packet, after all other channels
• the same channel cannot be associated with more than one widget
The same capabilities and limitations exist for the 3 input converter widgets (ADC1/2, S/PDIF RX). The
following table gives some examples of valid and invalid stream formats:
Stream Format
{A,B} {C,D} {E,F} {G,H} {I,J}
{A, B, C, D, E, F, G, H, I, J}
{A, B, C, D} {E, F}
{A, B} {C, D}
{A, B, C, D, E, F, G, H, I, J}
{A, B, C, D}
{A, B, C, D, E, F, G, H, I, J}
{A, B, C, D, E, F, G, H, I, J}
{A, B, C, D}
DAC1
A, B
A, B
A, B
-
G, H
-
A, B
A, B
A, B
DAC2
C, D
C, D
C, D
-
E, F
-
E, F
C, D
C, D
DAC3 SPDO1 SPDO2
comment
E, F G, H I, J indiv. streams, in-order assignment
E, F G, H I, J shared stream, in-order assignment
E, F
-
- mixed shared and indiv. streams
C, D
-
A, B indiv. streams, out of order assignment
A, B I, J C, D shared stream, out of order assignment
-
C, D
- invalid: leading unused ch. (A, B)
G, H I, J
- invalid: intermittent unused ch. (C, D)
E, F G, H
- ok: trailing unused ch. (I, J)
-
A, B
- invalid: ch. assigned to mult. widgets
The curly brackets { } delineate each stream packet. The letters within curly brackets designate each
channel within that stream packet. For instance the sequence “{A, B, C, D} {E, F}” denotes two streams -
one stream consisting of 4 channels A-D and one stream consisting of 2 channels E-F.
7.2 Analog Outputs
7.2.1
Analog Supply Removal
In order to reduce audible artifacts, the analog reference is always powered up, even if the AFG has been
transition-ed into D3 state. For maximum power savings during D3, it may be desirable to completely re-
move the analog supplies on the system level. Doing so would cause an uncontrolled discharge of the
internal reference and hence audible artifacts, and must therefore be preceded with a controlled reference
ramp-down, which is initiated by setting the PDREF bit in the DAC Configuration (CIR = 0003h) register
of the Vendor Processing Widget (Node ID = 11h).
7.3 Digital Mic Inputs
For each ADC, the data from the digital mic input pin widgets are multiplexed with the data from the analog
line/mic input pin widgets, and only one pin widget can be selected at any given time. Furthermore, the data
pins for the DMIC interface (DMIC_SDA1/2) are multiplexed with the GPIO0/1 pins and default to GPIO. In
order to successfully setup the data path for a digital microphone, the following steps have to be followed:
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