AD1986ABSTZ datasheet(23/56 Pages) AD

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AD1986A

Rev. 0 | Page 23 of 56

PC BEEP (REGISTER 0x0A)

This controls the level of the analog PC beep or the level and frequency of the digital PC beep. The volume register contains four bits,

generating 16 volume steps of −3.0 dB each for a range of 0 dB to −45.0 dB. The tone frequency can be set between 47 Hz to 12,000 Hz or

disabled.

Per Intel’s BIOS writer’s guide, the PC beep signal should play via headphone out, line out, and mono out paths. BIOS algorithms should

unmute the PC beep register and the path to each output, and set the volume levels for playback.

When the AD1986A is in reset (the external RESET pin is low), the PCBEEP_IN pin is connected internally to all of the device output

pins (HEADPHONE L/R, LINE_OUT L/R, MONO_OUT, SURROUND L/R, and CENTER/LFE). There are no amplifiers or attenuators

on this path and the external circuitry connected to this pin should anticipate the drive requirements for the multiple output sources.

Headphones connected to output pins will substantially load the signal.

Reg

Name

D15

D14

D13

D12

D11

D10

Default

0x0A

Beep

A/DS

0x8000

Table 77.

Function

Controls the gain into the output mixer from 0 dB to −45.0 dB. The least significant bit represents −3.0 dB. The gain default

is 0 dB and muted.

V3...V0

Function

Default

0000

0 dB

Default

1111

−45 dB attenuation

V [3:0]

(Analog or

Digital

Volume)

xxxx

Muted

The result of dividing the 48 kHz clock by four times this number, allowing tones from 47 Hz to 12 kHz. A value of 0x00

disables internal PC beep generation. The digitally-generated signal is close to a square wave and is not intended to be a

high quality signal.

F7...F0

Function

0000

Disabled

Default

0001

12,000 Hz tone

F [7:0]

(PC Beep

Frequency)

1111

47 Hz tone

A/DS

(PC Beep

Source)

Selects either the digital PC beep generator (= 0) or analog PCBEEP pin (= 1). When the

codec is in reset mode the analog PCBEEP pin is routed to the outputs via a high impedance

path. Once out of reset, this bit must be programmed to a 1 to pass through any signals on

the analog PCBEEP pin. Designers can choose not to connect the analog PCBEEP pin and

use the digital PC beep generator solely.

Default: digitally-selected

(0x0)

(PC Beep

Mute)

When this bit is set to 1, the PC beep signal (analog or digital) is muted.

Default: muted (0x1)

Reserved.

Default: 0

PHONE VOLUME (REGISTER 0x0C)

This register controls the PHONE_IN mute and gain to the analog mixer section. The volume register contains five bits, generating

32 volume steps of 1.5 dB each for a range of 12.0 dB to −34.5 dB. This does not control the record ADC gain (see Register 0x1C).

Reg

Name

D15

D14

D13

D12

D11

D10

Default

0x0C

Phone

Volume

0x8008

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