STAC9704 Datasheet, PDF (16/49 Pages) Hynix Semiconductor – Multimedia Audio Codec for AC97

SigmaTel, Inc.
STAC9704/7
3.1.1.2 Slot 2: Command Data Port
The command data port is used to deliver 16-bit control register write data in the event that
the current command port operation is a write cycle. (as indicated by Slot 1, bit 19)
Bit (19:4) Control Register Write Data (Stuffed with 0's if current operation is a read)
Bit (3 :0) Reserved
(Stuffed with 0's)
If the current command port operation is a read then the entire slot time must be stuffed with
0's by the AC'97 controller.
3.1.1.3 Slot 3: PCM Playback Left Channel
Audio output frame slot 3 is the composite digital audio left playback stream. In a typical
“Games Compatible" PC this slot is composed of standard PCM (.wav) output samples
digitally mixed (on the AC'97 controller or host processor) with music synthesis output
samples. If a sample stream of resolution less than 20-bits is transferred, the AC'97 controller
must stuff all trailing non-valid bit positions within this time slot with 0's.
3.1.1.4 Slot 4: PCM Playback Right Channel
Audio output frame slot 4 is the composite digital audio right playback stream. In a typical
“Games Compatible" PC this slot is composed of standard PCM (.wav) output samples
digitally mixed (on the AC'97 controller or host processor) with music synthesis output
samples. If a sample stream of resolution less than 20-bits is transferred, the AC'97 controller
must stuff all trailing non-valid bit positions within this time slot with 0's.
3.1.1.5 Slots 5-12: Reserved
Audio output frame slots 5-12 are reserved for future use and are always stuffed with 0's by
the AC'97 controller.
3.1.2 AC-link Audio Input Frame (SDATA_IN)
The audio input frame data streams correspond to the multiplexed bundles of all digital input data
targeting the AC'97 controller. As is the case for audio output frame, each AC-link audio input frame
consists of 12, 20-bit time slots. Slot 0 is a special reserved time slot containing 16 bits that are used for
AC-link protocol infrastructure.
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