CS4298 Datasheet, PDF (16/52 Pages) Cirrus Logic – SoundFusion Audio/Modem Codec 97 (AMC 97)

CS4298
5. AC ‘97
5.1 AC ‘97 Frame Definition
The AC Link is a bi-directional serial port with thirteen time-division multiplexed slots in each di-
rection. The first slot is 16 bits long and termed the tag slot. Bits in the tag slot determine if the Codec
is ready and indicate which, if any, other slots contain valid data. Slots 1 through 11 are 20-bits long
and can contain audio data. Slot 12 contains data to be written and read from GPIO. The serial data
line is defined from the Controller’s perspective, NOT from the Audio Codec’s perspective.
5.2 AC-Link Serial Data Output Frame
In the serial data output frame, data is passed on the SDATA_OUT pin TO the CS4298 FROM the
Controller. Figure 9 illustrates the serial port timing.
Tag Phase
SYNC
BIT_CLK
12.288 MHz
81.4 nS
20.8 µS
(48 kHz)
Data Phase
Bit Frame Position: F255
SDATA_OUT X
F0
Valid
Frame
F1
Slot 1
Valid
F2
Slot 2
Valid
F12
F13
F14 F15
F16
0
0 SCRA1 SCRA0 R/W
F35
F36
F56
F57
F76
F97
F255
0 WD15
LP19 LP18
RP19
X
X
Bit Frame Position: F255
SDATA_IN
0
F0
Codec
Ready
F1
Slot 1
Valid
F2
Slot 2
Valid
F12
F13
F14 F15
F16
0
0
0
0
0
F35
F36
F56 F57
F76
F97
F255
0 RD15
LC17 LC16
RC17
0
0
Slot 0
Slot 1
Slot 2
Slot 3
Figure 9. AC-link Input and Output Framing
Slot 4
Slots 5-12
16
DS315PP2