Colibri iMX6 Microphone Gain

We are using Colibri iMX6 with Wind CE 8.0 and we need to manage the microphone gain. need to adjust the speaker and mic volume

Colibri iMX6 audio uses SGTL5000 audio codec.

Have a look at it here on how to access SGTL5000 registers.

If you simply want to increase/decrease the volume, you can do it from the control panel.
Start->Settings->Control Panel->Volume&Sounds, adjust the volume, save registry and reboot.