FW82801EB Intel, FW82801EB Datasheet - Page 262

• Manufacturer Part Number: FW82801EB
• Manufacturer: Intel

Specifications of FW82801EB

• Lead Free Status / RoHS Status: Not Compliant

Functional Description
5.22.3
262
Table 128. Output Tag Slot 0
Figure 28. AC-Link Powerdown Timing
When accessing the codec registers, only one I/O cycle can be pending across the AC-link at any
time. The ICH5 implements write posting on I/O writes across the AC-link (i.e., writes across the
link are indicated as complete before they are actually sent across the link). In order to prevent a
second I/O write from occurring before the first one is complete, software must monitor the CAS
bit in the Codec Access Semaphore register which indicates that a codec access is pending. Once
the CAS bit is cleared, then another codec access (read or write) can go through. The exception to
this being reads to offset 54h/D4h/154h (slot 12) which are returned immediately with the most
recently received slot 12 data. Writes to offset 54h, D4h, and 154h (primary, secondary and tertiary
codecs), get transmitted across the AC-link in slots 1 and 2 as a normal register access. Slot 12 is
also updated immediately to reflect the data being written.
The controller does not issue back to back reads. It must get a response to the first read before
issuing a second. In addition, codec reads and writes are only executed once across the link, and are
not repeated.
AC-Link Low Power Mode
The AC-link signals can be placed in a low-power mode. When the AC ’97 Powerdown register
(26h), is programmed to the appropriate value, both AC_BIT_CLK and AC_SDIN will be brought
to, and held at a logic low voltage level.
12:3
Bit
1:0
15
14
13
2
Primary Access
Example
00
X
1
1
1
0
Note:
BIT_CLK not to scale
BIT_CLK
SDOUT
SDIN
Secondary Access
SYNC
Example
01
1
0
0
X
0
prev. frame
prev. frame
slot 12
slot 12
Frame Valid
Slot 1 Valid, Command Address bit (Primary codec only)
Slot 2 Valid, Command Data bit (Primary codec only)
Slot 3–12 Valid
Reserved
Codec ID (00 reserved for primary; 01 indicate secondary;
10 indicate tertiary)
Intel
TAG
TAG
®
82801EB ICH5 / 82801ER ICH5R Datasheet
Write to
0x20
Description
Data
PR4