ALS300 Datasheet, PDF (47/66 Pages) List of Unclassifed Manufacturers – Media Audio Controller SPEC

Avance Logic Inc.
ALS300
AC Link Bit 3 ↔ (Output : stuffed with 0 , Input : discarded)
:
:
AC Link Bit 0 ↔ (Output : stuffed with 0 , Input : discarded)
z PCM Sample Order:
8 Bit Mono
Byte No.
3
2
1
0
z Sample
8 Bit Stereo
PCM 3 PCM 2 PCM 1 PCM 0
Byte No.
3
2
1
0
Sample PCM1.R PCM1.L PCM0.R PCM0.L
z 16 Bit Mono
Byte No.
3
2
1
0
Sample PCM1.HIGH PCM1.LOW PCM0.HIGH PCM0.LOW
z 16 Bit Stereo
Byte No.
3
2
1
0
Sample PCM0.R.High PCM0.R.Low PCM0.L.High PCM0.L.Low
Transformation between different PCM data type :
The PCM data type for AC97 is 16-bit signed PCM data. The transformations are described
below :
Unsigned → Signed 16-bit(8-bit)
Unsigned value
Signed value
FFFFh(FFh)
7FFFh(7Fh)
:
:
8001h(81h)
0001h(01h)
8000h(80h)
0000h(00h)
7FFFh(7Fh)
FFFFh(FFh)
:
:
0000h(00h)
8000(80h)
Mono → Stereo
Duplicated Left channel to Right channel.
8-bit → 16-bit
Stuff low byte with 0.
The transformation sequence are :
n Unsigned → Signed
o 8-bit → 16-bit
p Mono → Stereo
AC97 Mixer Read procedure :
1.Check AC97-STATUS bit 7, if bit7=1 go to 1,else go to 2.
2.Write mixer index to AC97-ACCESS(bit 24~31) with bit 31=1(Read operation)
3.Check AC97-STATUS bit 6, if bit 6=0 goto 3, else goto 4.
4.Read data from AC97-READ.
AC97 Mixer Write procedure :
1.Check AC97-STATUS bit 7, if bit 7 =1 go to 1,else go to 2.
2.Write index and data to AC97-ACCESS with bit 31=0
Wave Engine RAM access :
The working RAM of wave engine is 128 x 32 RAM. It can be accessed via “Address” port
and 32-bit “Data” port.
Note for Interrupt Service Routine(ISR) and TSR :
Because ALS300 share one IRQ line with multiple IRQ request., the TSR developer will
pay more attention to decide which request to be served.
For TSR :
1.Mask INTA# output. (Set GCR8C.15) ,check IRQ-STATUS and acknowledge
IRQs.
2.Call corresponding ISRs (higher-priority ISR first)
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