STAC9750 Datasheet, PDF (36/73 Pages) Integrated Device Technology – VALUE-LINE TWO-CHANNEL AC’97 CODECS

STAC9750/9751
VALUE-LINE TWO-CHANNEL AC’97 CODECS
PC AUDIO
6.5.3.
Note: If optional bits D13 & D5 of register 04h are set to 1, then the corresponding attenuation is set to
46.5dB and the register reads will produce 1Fh as a value for this attenuation/gain block.
D15
D14
Mute
RSRVD
D7
D6
Reserved
D13
HPL5
D5
HPR5
D12
HPL4
D4
HPR4
D11
HPL3
D3
HPR3
D10
HPL2
D2
HPR2
D9
HPL1
D1
HPR1
D8
HPL0
D0
HPR0
6.5.2.3. Master Volume MONO (06h)
Default: 8000h
Note: If optional bit D5 of register 06h is set to 1, then the corresponding attenuation is set to 46.5dB and the
register reads will produce 1Fh as a value for this attenuation/gain block.
D15
D14
Mute
D7
D6
Reserved
D13
D5
MM5
D12
D4
MM4
D11
Reserved
D3
MM3
D10
D2
MM2
D9
D1
MM1
D8
D0
MM0
PC Beep Mixer Volume (Index 0Ah)
Default: 0000h
Note: PC_BEEP defaults to 0000h, mute off.
D15
D14
D13
Mute
D7
D6
D5
Reserved
D12
D11
D10
Reserved
D4
D3
D2
PV3
PV2
PV1
D9
D8
D1
D0
PV0
RSRVD
This register controls the level for the PC Beep input. Each step corresponds to approximately 3dB
of attenuation. The MSB of the register is the mute bit. When this bit is set to 1, the level for that
channel is set at -∞dB. PC_BEEP supports motherboard implementations. The intention of routing
PC_BEEP through the STAC9750/9751 mixer is to eliminate the requirement for an onboard
speaker by guaranteeing a connection to speakers connected via the output jack. In order for this to
be viable, the PC_BEEP signal needs to reach the output jack at all times. NOTE: the PC_BEEP is
routed to the mono outputs when the STAC9750/9751 is in a RESET state. This is so that Power On
Self Test (POST) codes can be heard by the user in case of a hardware problem with the PC. For
further PC_BEEP implementation details please refer to the AC'97 Technical FAQ sheet. The default
value is 0000h, which corresponds to 0 dB attenuation with mute off.
Mute
0
0
1
Table 17. PC_BEEP Register
PV3…PV0
0000
1111
xxxx
Function
0 dB Attenuation
45 dB Attenuation
∞ dB Attenuation
IDT™
VALUE-LINE TWO-CHANNEL AC’97 CODECS
36
STAC9750/9751
V 5.8 103106