AD1985

Rev. A | Page 39 of 48

Miscellaneous Control Bits (Index 0x76)

Reg

Num

Name

D15

D14

D13

D12

D11

D10

D9

D8

D7

D6

D5

D4 D3

D2

D1

D0

Default

0x76

Misc

Control Bits

DACZ AC97NC MSPLT LODIS CLDIS HPSEL DMIX1 DMIX0 SPRD 2CMIC LOSEL SRU VREFH VREFD MBG1 MBG0 0x0000

MBG[1:0]

MIC Boost Gain Select Register. These two bits allow changing both MIC preamp gain blocks from the nominal +20 dB

gain boost. Both MIC1 and MIC2 preamps will be set to the same selected gain.

Note: This gain setting only takes effect while Bit D6 (M20) on the MIC volume register (0x0E) is set to 1, otherwise, the MIC

boost blocks have a gain of 0 dB.

00: +20 dB gain. (Reset default.)

01: +10 dB gain.

10: +30 dB gain.

11: Reserved.

VREFH

VREFD

0

0

2.25 V (Default)

0

1

High-Z

1

0

3.7 V

VREFD, VREFH

1

1

0 V

SRU

Sample Rate Unlock. Controls all DAC sample rate locking.

0: All DAC sample rates are locked to the front sample rate. (Reset default.)

1: DAC sample rates can be set independently for front, surround, and LFE.

LOSEL

LINE_OUT Amplifiers Input Select. This bit allows the LINE_OUT output amplifiers to be driven by the mixer or the

surround DACs. The main purpose for this is to allow swapping of the front and surround channels to make better use of

the SURR/HP_OUT output amplifiers. This bit should normally be used in tandem with the HPSEL bit (see below).

0: LINE_OUT amplifiers are driven by the mixer outputs. (Reset default.)

1: LINE_OUT amplifiers are driven by the surround DAC outputs.

2CMIC

2-Channel MIC Select. This bit enables simultaneous recording from MIC1 and MIC2 inputs, using a stereo microphone

array. Note that this register works in conjunction with the MS and OMS bits.

0: MIC1 or MIC2 (determined by MS bit) is routed to the mixer/record selector’s left and right MIC channels. (Reset default.)

1: MIC1 is routed to the mixer/record selector’s left MIC channel, and MIC2 is routed to the mixer/record selector’s right

MIC channel. The MS bit will swap the MIC1/MIC2 left and right assignments.

The OMS bit will select from the MIC1/MIC2 or Center/LFE pins as the input source for the microphone. See the Record

Selector (Register 0x1A), MS bit (Bit D8, Register 0x20), or OMS bit (Bit D9, Register 0x74) definitions for more information.

SPRD

Spread Enable. This bit enables spreading of 2-channel media to all six output channels. This function is implemented in

the analog section by using the output selector control lines for the center/LFE, surround, and LINE_OUT output channels.

Note that the jack sense pins can also be set up to control (gate) this function depending on the JS1SPRD bit (see

Register 0x72).

0: No Spreading occurs, unless activated by the jack senses and JS1SPRD bit. (Reset default.)

1: The SPRD selector drives the center and LFE outputs from the MONO_OUT, the HPSEL selector drives the SURR/HP_OUT

outputs from the mixer outputs, and the LOSEL selector drives the LINE_OUT outputs from the mixer outputs.

Note that the SPRD bit overrides the current output selector control lines, set up by Bits LOSEL and HPSEL as follows:

LOSEL = 0 and HPSEL = 1.