stac9708 ETC-unknow, stac9708 Datasheet - Page 30

• Manufacturer Part Number: stac9708
• Description: Multi-channel Ac97 Codec With Multi-codec Option
• Manufacturer: ETC-unknow

SigmaTel, Inc.
4.4.6 Record Gain Registers (Index 1Ch)
The 1Ch register adjusts the stereo input record gain. Each step corresponds to 1.5 dB. 22.5 dB
corresponds to 0F0Fh and 000Fh respectively. The MSB of the register is the mute bit. When this bit
is set to 1, the level for that channel(s) is set at - dB.
The default value is 8000h, which corresponds to 0 dB gain with mute on.
4.4.7 General Purpose Register (Index 20h)
This register is used to control some miscellaneous functions. Below is a summary of each bit and its
function. The MS bit controls the mic selector. The LPBK bit enables loopback of the ADC output to
the DAC input without involving the AC-Link, allowing for full system performance measurements.
4.4.8 3D Control Register (Index 22h)
This register is used to control the 3D stereo enhancement function, Sigmatel Surround 3D (SS3D),
built into the AC'97 component. Note that register bits, DP1-DP0 and DPR1-DPR0 are used to control
the separation ratios in the 3D control for both LINE_OUT and DAC_OUT respectively. This allows
LPBK
MIX
BIT
MS
3D
MUTE
Table 15. General Purpose Register
0
0
1
Table 14. Record Gain Registers
3D Stereo Enhancement on/off 1 = on
Mono output select 0 = Mix, 1= Mic
Mic select 0 = Mic1, 1 = Mic2
Gx3… Gx0
Preliminary
ADC/DAC loopback mode
1111
0000
xxxx
30
FUNCTION
+22.5 dB gain
FUNCTION
0 dB gain
- gain
STAC9708/11
10/02/98