VT82C686B
The audio / modem interface is compliant with AC97. Refer
to the AC97 specification and AC97 Codec data sheets for
further details.
Offset 87-84 – SGD Status Shadow .................................. RO
Read / Only through both functions 5 and 6.
........................................always reads 0
31-30 Reserved
Read / Write through both functions 5 and 6.
29 Modem Write Chan SGD Active Shadow(Rx50[7])
28 Modem Read Chan SGD Active Shadow (Rx40[7])
........................................always reads 0
27-26 Reserved
Offset 83-80 – AC97 Controller Command / Status.......RW
25 Modem Write Chan SGD STOP Shadow (Rx50[2])
24 Modem Read Chan SGD STOP Shadow.(Rx40[2])
Read / Write through both functions 5 and 6.
......................................................... RW
00 Select Primary Codec
31-30 Codec ID
........................................always reads 0
23-22 Reserved
01 Select Secondary Codec
1x -reserved-
21 Modem Write Chan SGD EOL Shadow..(Rx50[1])
20 Modem Read Chan SGD EOL Shadow...(Rx40[1])
........................................ always reads 0
29-28 Reserved
........................................always reads 0
19-18 Reserved
.RWC
27 Secondary Codec Data / Status / Index Valid
17 Modem Write Chan SGD FLAG Shadow(Rx50[0])
16 Modem Read Chan SGD FLAG Shadow (Rx40[0])
0
Not Valid
1
Valid (OK to Read bits 0-23)
........................................ always reads 0
26 Reserved
........................................always reads 0
15 Reserved
.....RWC
25 Primary Codec Data / Status / Index Valid
14 FM Channel SGD Active Shadow............(Rx20[7])
13 Audio Write Chan SGD Active Shadow..(Rx10[7])
12 Audio Read Chan SGD Active Shadow...(Rx00[7])
........................................always reads 0
10 FM Channel SGD STOP Shadow ............(Rx20[2])
0
1
Not Valid
Valid (OK to Read bits 0-23)
.........................................RO
24 AC97 Controller Busy
11 Reserved
0
Primary Codec is ready for a register access
command
AC97 Controller is sending a command to the
primary codec (commands are not accepted)
9
8
Audio Write Chan SGD STOP Shadow ..(Rx10[2])
Audio Read Chan SGD STOP Shadow ...(Rx00[2])
1
............ RW
23 Codec Command Register Write Mode
........................................always reads 0
7
6
5
4
3
2
1
0
Reserved
0
1
Select Codec command register write mode
Select Codec command register read mode
.............. RW
FM Channel SGD EOL Shadow ..............(Rx20[1])
Audio Write Chan SGD EOL Shadow ....(Rx10[1])
Audio Read Chan SGD EOL Shadow .....(Rx00[1])
22-16 Codec Command Register Index [7:1]
Index of the AC97 codec command register to access
(in the attached codec). Data must be written before
or at the same time as Index as writing to the index
triggers the AC97 controller to access the addressed
codec register over the AC-link interface.
........................................always reads 0
Reserved
FM Channel SGD FLAG Shadow............(Rx20[0])
Audio Write Chan SGD FLAG Shadow..(Rx10[0])
Audio Read Chan SGD FLAG Shadow...(Rx00[0])
........... RW
15-0 Codec Command Register Data / Status
W Codec Command Register Data
Read / Only through function 5 and Read / Write through
function 6:
R
Codec Status Register Data
Offset 8B-88 – Codec GPI Interrupt Status / GPIO ... RWC
........................................ RWC
31-16 GPI Interrupt Status
R
GPI[15-0] Interrupt Status
W 1 to clear
.........................................................RW
15-0 Codec GPIO
R
Reflect status of Codec GPI[15-0]
W Triggers AC-Link slot-12 output to codec
Offset 8F-8C – Codec GPI Interrupt Enable ................. RW
..........RW
31-16 Interrupt on GPI[15-0] Change of Status
0
1
Disable
Enable
........................................always reads 0
15-0 Reserved
Revision 1.71 June 9, 2000
-113- Function 5 & 6 Registers - AC97 Audio & Modem Codecs
ETC [ ETC ]
