TS-7970 3.5mm Audio Ports

From embeddedTS Manuals

The TS-7970 includes two 3.5mm jacks. The top port is a mono microphone input, and the bottom port is a headphone port with left and right channels. Use "alsamixer" or "amixer" to adjust the volume.

In Linux select between the HDMI and 3.5mm ports with an alsa variable. By default all audio comes out of the sgtl5000 for the 3.5mm ports.

# list the sound cards
aplay -l

export ALSA_CARD=imxhdmisoc
espeak "this is playing from the HDMI monitor"

## On kernel 4.1:
#export ALSA_CARD=imx6qts7970sgtl
## On kernel 4.9
export ALSA_CARD=Codec
espeak "this is playing from the onboard sgtl5000"