CMI9738 Datasheet, PDF (15/36 Pages) List of Unclassifed Manufacturers – Integrated Multi-channel AC97

CMI 9738
Integrated Multi-channel AC‘97
The first bit (MSB) sampled by CMI9738 indicates whether the current control transaction is a
read or a write operation. The following 7 bit positions communicate the targeted control register
address. The trailing 12 bit positions within the slot are reserved and must be stuffed with 0’s by
the AC ’97 Controller.
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.
Slot 3: PCM Playback Left Channel
Games Compatible" PC this slot is composed of standard PCM (.wav) output samples digitally
mixed (by 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.
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 (by 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.
Slot 5: Reserved
Audio output frame slot 5 is reserved for modem operation and is not used by the CMI9738.
Slot 6: PCM Center Channel
Audio output frame slot 6 is not used by the CMI9738.
Slot 7: PCM Left Surround Channel
Slot 7 carries PCM left surround data in 4 channel wave output.
Slot 8: PCM Right Surround Channel
Slot 8 carries PCM right surround data in 4 channel wave output.
Slot 9: PCM Low Frequency Channel
Audio output frame slot 9 is not used by the CMI9738.
Slot 10: PCM Alternate Left
Audio output frame slot 10 is not used by the CMI9738.
Slot 11: PCM Alternate Right
Audio output frame slot 11 is not used by the CMI9738.
Slot 12: Reserved
C-MEDIA Electronics Inc.
6F, 100, Sec. 4, Civil Boulevard, Taipei, Taiwan, R.O.C. 106
TEL: [phone] FAX: [phone] E-mail:[e-mail]
Revision Date Apr./2002
Revision 1.1