CS4298 Datasheet, PDF (17/52 Pages) Cirrus Logic – SoundFusion Audio/Modem Codec 97 (AMC 97)

CS4298
5.3 AC-Link AudioOutput Frame
5.3.1 Serial Data Output Slot Tags (Slot 0)
Bit 15 14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
Valid Slot 1 Slot 2 Slot 3 Slot 4 Slot 5 Slot 6 Slot 7 Slot 8 Slot 9 Slot 10 Slot 11 Slot 12
SCRA SCRA
Frame Valid Valid Valid Valid Valid Valid Valid Valid Valid Valid Valid Valid
1
0
Valid FrameDetermines if any of the following slots contain either valid playback data for the Codec’s DACs, data
for read/write operation, or GPIO data. When set, at least one of the other AC-link slots contain valid
data. If this bit is clear, the remainder of the frame is ignored.
Slot [1:2] ValidIndicates valid slot data when accessing the register set of the primary Codec (SCRA[1:0] = 00). For
a read operation, Slot 1 Valid is set when Register Address (Slot 1) contains valid data. For a write op-
eration, Slot 1 Valid and Slot 2 Valid are set indicating Register Address (Slot 1) and Register Write Data
(Slot 2) contain valid data. The register address and write data must be valid within the same frame.
SCRA[1:0] must be cleared when accessing the primary Codec. The physical address of a Codec is
determined by the ID[1:0]# input pins which are reflected in the Extended Audio ID (Index 28h) register
and the Extended Modem ID (Index 3Ch) register.
Slot [3:11] Valid
If a Slot Valid bit is set, the named slot contains valid audio data. If the bit is clear, the slot will be ignored.
The definition of each slot is determined by the basic operating mode selected for the CS4298. For more
information, see the AC Mode Control (Index 5Eh) register.
Slot 12 ValidIf Slot 12 Valid is set, Slot 12 contains valid write data for the GPIO pins.
SCRA[1:0] Secondary Codec Register Access. Unlike the primary Codec, SCRA[1:0] indicate valid slot data when
accessing the register set of a secondary Codec. The value set in SCRA[1:0] (01,10,11) determines
which of the three possible secondary Codecs is accessed. For a read operation, the SCRA[1:0] bits
are set when Register Address (Slot 1) contains valid data. For a write operation, SCRA[1:0] bits are
set when Register Address (Slot 1) and Register Write Data (Slot 2) contain valid data. The write oper-
ation requires the register address and the write data to be valid within the same frame. SCRA[1:0] must
be cleared when accessing the primary Codec. They must also be cleared during the idle period where
no register read or write is pending. The physical address of a Codec is determined by the ID[1:0]# input
pins which are reflected in the Extended Audio ID (Index 28h) register and the Extended Modem ID (In-
dex 3Ch) register. The SCRA[1:0] bits are listed as the ID[1:0] bits in Slot 0 in the AC ‘97 specification.
5.3.2 Register Address (Slot 1)
Bit 19 18 17 16 15 14 13 12 11 10 9
8
7
6
5
4
3
2
1
0
R/W# RI6 RI5 RI4 RI3 RI2 RI1 RI0
R/W #
RI[6:0]
Read/Write#. Determines if a read (R/W# = 1) or write (R/W# = 0) operation is requested. For a read
operation, the following Input Frame will return the register index in the Read-Back Address Port (Slot
1) and the contents of the register in the Read-Back Data Port (Slot 2). A write operation does not return
any valid data in the following frame. If the R/W# bit = 0, data must be valid in both the Register Address
(Slot 1) and the Register Write Data (Slot 2) during a frame when Slot [1:2] Valid or SCRA[1:0] are set.
Register index/address. Registers can only be accessed on word boundaries; RI0 must be set to 0.
RI[6:0] must contain valid data during a frame when the Slot 1 Valid or SCRA[1:0] are set.
DS315PP2
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