4-8
Mixer Chip Programming
Register 0x0A (Mic mixing volume)
2 bits, giving 4 levels.
0 to 3
⇒
–
46 dB to 0 dB, in approximate 7 dB steps.
Default is 0
⇒
–
46 dB.
Register 0x0C:1,2 (Input Source)
Set these two bits to one of the following values to select the input source.
0 or 2
⇒
Microphone source.
1
⇒
CD source.
3
⇒
Line-in source.
Default is 0
⇒
Microphone.
Register 0x0C:3 (Low-Pass Filter)
Low-pass input filter. It is only effective when the Input Filter switch is
on.
0
⇒
3.2 kHz low-pass filter.
1
⇒
8.8 kHz low-pass filter.
Default is 0
⇒
3.2 kHz low-pass filter.
Register 0x0C:5 (Input Filter)
Input filter off switch.
0
⇒
Input filter on, pass through low-pass filter.
1
⇒
Input filter off, bypass low-pass filter.
Default is 0
⇒
Input filter on.
The low-pass filter is used to filter off high-frequency signals
during recording to achieve better recording quality.
As a general guide, use the 3.2 kHz filter for mono recording
with sampling rates below 18 kHz; use the 8.8 kHz filter for
mono recording with sampling rates between 18 kHz to 36 kHz.
Turn off both filters for mono recording with sampling rates
above 36 kHz, or for any stereo recording.
