STAC9758 Datasheet, PDF (54/119 Pages) Integrated Device Technology – HIGH-PERFORMANCE 6-CHANNEL AC’97 2.3 CODEC WITH UNIVERSAL JACKS

STAC9758/9759
HIGH-PERFORMANCE 6-CHANNEL AC’97 2.3 CODEC WITH UNIVERSAL JACKS™
PC AUDIO
8.2.6.
Digital PC Beep
The AC’97 2.3 specification calls for the CODEC to generate a square wave tone at a particular vol-
ume and frequency. Typically, the BIOS will program this register during the Power On Self Test
(POST) cycle.
To create a tone using Digital PC Beep, write a non-zero value to the F Bits in Reg 0Ah (bits
D12:D5). The beep frequency is the result of dividing the 48KHz clock by 4 times the number spec-
ified in F[7:0], allowing tones from 47Hz to 12KHz. (see Table18: page54). Set the PV bits in Reg
0Ah, (Bits D4:D1) control the volume level from 0 to 45dB of attenuation in 3dB steps. Unmute bit
D15 if necessary.
To stop the tone, write 801Fh to Reg 0Ah. This turns off the generator, turns the volume to the low-
est setting, and mutes the register.
Applying a signal to the PC Beep pin, pin 12, may cause the digital PC Beep signal to become dis-
torted or inaudible. When using the digital PC Beep feature, leave the PC Beep input pin connected
to analog ground through a capacitor. Connecting a capacitor from the PC Beep input pin to ground
will create a more pleasing sound by changing the digital output to a more sinusoidal like output.
Table 18. Digital PC Beep Examples
Value
1
10
25
50
100
127
255
Reg 0Ah [D12:D5]
0x01
0x0A
0x19
0x32
0x64
0x0F
0xFF
Frequency
12,000Hz
1200Hz
480 Hz
240 Hz
120 Hz
94.48 Hz
47.05 Hz
Typically this feature will be used exclusively by the BIOS, and will not be used by Controller or
Driver.
8.2.7. Phone Volume (0Ch)
Default: 8008h.
D15
D14
D13
Mute
D7
D6
D5
RESERVED
D12
D4
GN4
D11
RESERVED
D3
GN3
D10
D2
GN2
D9
D1
GN1
Bit(s) Reset Value R/W
15
1
RW
Name
Mute
0 = no mute
1 = mute phone
Description
D8
D0
GN0
IDT™
54
HIGH-PERFORMANCE 6-CHANNEL AC’97 2.3 CODEC WITH UNIVERSAL JACKS™
STAC9758/9759
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