AD1981A Analog Devices, AD1981A Datasheet - Page 13

• Manufacturer Part Number: AD1981A
• Description: AD1981A AC'97 Soundmax Codec
• Manufacturer: Analog Devices

RIM[3:0]
RM
LIM[3:0]
IM
LPBK
Reg Num Name
For AC ‘97 compatibility, Bit D7 (RM) is only available by setting the MSPLT bit Register 76h. The MSPLT bit enables separate mute bits for the left and right
channels. If MSPLT is not set, RM bit has no effect.
Reg Num Name
This register should be read before writing to generate a mask for only the bit(s) that need to be changed.
1Ch
20h
Record Gain
General Purpose
Right Input Mixer Gain Control: Each LSB represents 1.5 dB, 0000 = 0 dB, and the range is 0 dB to 22.5 dB.
Right Channel Mute: Once enabled by the MSPLT Bit in Register 76h, this bit mutes the right channel separately
from the IM bit. Otherwise, this bit will always read “0” and will have no effect when set to “1.”
Left Input Mixer Gain Control: Each LSB represents 1.5 dB, 0000 = 0 dB, and the range is 0 dB to 22.5 dB.
Input Mute: When this bit is set to “1,” both L/R channels are muted unless the MSPLT Bit in Register 76h is set
to “1,” in which case this mute bit will only affect the left channel.
Loop-Back Control: ADC/DAC digital loop-back mode
D15 D14 D13 D12 D11
IM
RS1...RS0
0
1
2
3
4
5
6
7
LS1...LS0
0
1
2
3
4
5
6
7
X
D15 D14 D13 D12 D11 D10 D9 D8
X
X
X
X LIM3 LIM2 LIM1 LIM0 RM
IM
0
0
1
General Purpose Register (Index 20h)
X
Record Gain (Index 1Ch)
X
Right Record Source
MIC
CD_R
Muted
AUX_R
LINE_IN_R
Stereo Mix (R)
Mono Mix
PHONE_IN
Left Record Source
MIC
CD_L
Muted
AUX_L
LINE_IN_L
Stereo Mix (L)
Mono Mix
PHONE_IN
D10
X
xIM3...xIM0
1111
0000
xxxxx
D9
X
X
D8
X LPBK X
D7 D6 D5 D4
D7
X
Function
+22.5 dB Gain
0 dB Gain
–∞ dB Gain
X
D6 D5 D4 D3 D2 D1 D0 Default
X RIM3 RIM2 RIM1 RIM0 8000h
X
D3
X
X
D2
X
D1
X
AD1981A
D0
X
0000h
Default