How to support voice over USB in i.MX8

[sudarshan_gajan]

Hi,

We are working on i.MX8M mini with Android P9.0.0(With kernel version 4.14.98)

We are planning to validate call feature in the 4G module with i.MX8M.

The i.MX8M Mini, EC25 and Audio codec connected as shown in attached image.

We tried below command for voice over USB feature.

AT+QGPSCFG=“outport”,“none”
OK

AT+QPCMV=1,0
OK

ATD**********;
OK

After that we are able to connect the call to corresponding mobile,

But we not able to hear Sound through attached earphone to the audio In/Out jack in i.MX8M mini development kit through voice over USB AT commands.

Kindly suggest me to solve the issue.

Thank You,
Regards,
Sudarshan

[jamesbone]

Hello Sudarshan,

from your design,  I understand that the USB port it is only configured as CDC,  USB to Serial, but I do not see, that you are going to handle the AUDIO through this channel,  this way I do not see any bridge between the USB and I2S, which it is handle by ALSA or directly by the Android APP, so at the end, you need to make this bridge from the USB to change ISOCHRONUS or any other USB to AUDIO and then send it to the I2S.