ADSP-1981BL AD [Analog Devices], ADSP-1981BL Datasheet - Page 20

• Manufacturer Part Number: ADSP-1981BL
• Description: AC 97 SoundMAX Codec
• Manufacturer: AD [Analog Devices]

AD1981BL
Table 26. Settings for Record Gain Register
Reg. 0x76
MSPLT
0
0
0
1
1
1
1
GENERAL-PURPOSE REGISTER
Index 0x20
Reg No.
0x20
Table 27.
Bit
LPBK
MS
MIX
This register should be read before writing to generate a mask for only the bit(s) that need to be changed.
For AC ’97 compatibility, Bit D7 (RM) is available only by setting the MSPLT bit, Register 0x76. The MSPLT bit enables separate mute bits for the left and right channels.
If MSPLT is not set, the RM bit has no effect.
All registers are not shown, and bits containing an X are assumed to be reserved.
X is a wild card, and has no effect on the value.
1
Mnemonic
Loopback Control
MIC Select
Mono Output Select
Name
General-Purpose
D15
0
0
1
0
1
1
Left-Channel Input Mixer D [11:8]
D15
X
Write
1111
0000
XXXX
1111
XXXX
XXXX
D14
X
Function
ADC/DAC Digital Loopback Mode.
0 = No Loopback (default).
1 = Loopback PCM Digital Data from ADC Output to DAC.
Selects mono MIC input.
0 = Select MIC1.
1 = Select MIC2.
See the 2CMIC bit in Register 0x76 to enable stereo microphone recording.
Selects mono output audio source.
0 = Mixer Mono Output (reset default).
1 = MIC1 Channel.
D13
X
Readback
1111
0000
XXXX
1111
XXXX
XXXX
D12
X
D11
X
Control Bits Record Gain (1Channel)
Rev. A | Page 20 of 32
Function
22.5 dB Gain
0 dB Gain
−∞ dB Gain,
Muted
22.5 dB Gain
−∞ dB Gain,
Left Only
Muted
−∞ dB Gain,
Left Muted
D10
X
D9
MIX
D8
MS
D7
X
X
X
1
0
1
1
D7
LPBK
D6
X
Right-Channel Input Mixer D [3:0]
Write
1111
0000
XXXX
XXXX
1111
XXXX
D5
X
D4
X
D3
X
Readback
1111
XXXX
1111
XXXX
0000
XXXX
D2
X
D1
X
X
D0
Function
22.5 dB Gain
0 dB Gain
−∞ dB Gain,
Muted
−∞ dB Gain,
Right Only
Muted
22.5 dB Gain
−∞ dB Gain,
Right Muted
Default
0x0000