Audio In

The Audio Output should be verified to work before attempting the audio input tests in this section.

Carrier Board	Audio In	Audio Out
SOM Carrier Board	Microphone jack	Headphone jack and HDMI

U-Boot

Audio in is currently not supported in U-Boot.

Linux

As described it the Audio Out section it is possible to see all the audio mixer controls.

amixer controls

numid=39,iface=MIXER,name='Headphone Gain Ramping Switch'
numid=34,iface=MIXER,name='Headphone ZC Switch'
numid=28,iface=MIXER,name='Headphone Switch'
numid=7,iface=MIXER,name='Headphone Volume'
numid=40,iface=MIXER,name='Lineout Gain Ramping Switch'
numid=29,iface=MIXER,name='Lineout Switch'
numid=8,iface=MIXER,name='Lineout Volume'
numid=75,iface=MIXER,name='Mic 1 Amp Source MUX'
numid=23,iface=MIXER,name='Mic 1 Switch'
numid=1,iface=MIXER,name='Mic 1 Volume'
numid=76,iface=MIXER,name='Mic 2 Amp Source MUX'
numid=24,iface=MIXER,name='Mic 2 Switch'
numid=2,iface=MIXER,name='Mic 2 Volume'
numid=35,iface=MIXER,name='Aux Gain Ramping Switch'
numid=32,iface=MIXER,name='Aux ZC Switch'
numid=25,iface=MIXER,name='Aux Switch'
numid=3,iface=MIXER,name='Aux Volume'
numid=37,iface=MIXER,name='ADC Gain Ramping Switch'
numid=16,iface=MIXER,name='ADC HPF Cutoff'
numid=15,iface=MIXER,name='ADC HPF Switch'
numid=18,iface=MIXER,name='ADC Voice Cutoff'
numid=17,iface=MIXER,name='ADC Voice Mode Switch'
numid=27,iface=MIXER,name='ADC Switch'
...

Audio Recording

One way to test audio is to record from the microphone and then play it back.

Enable the microphone.

amixer -q cset name='Mic 1 Volume' 71%
amixer -q cset name='Mic 1 Switch' on
amixer -q cset name='Mic 1 Amp Source MUX' 'Differential'
amixer -q cset name='Mixin Left Mic 1 Switch' on
amixer -q cset name='Mixin Right Mic 1 Switch' on
amixer -q cset name='Mixin PGA Volume' 47
amixer -q cset name='Mixin PGA Switch' on
amixer -q cset name='ADC Volume' 76%
amixer -q cset name='ADC Switch' on

Record 5 seconds in CD quality.

arecord -d 5 -fcd myfile.wav

Disable microphone.

amixer -q cset name='Mic 1 Switch' off

Play recorded audio.

aplay myfile.wav

If you don't hear any audio check the settings in the Audio Out section.