EG25 and UAC for audio

IoT Modules LTE Standard Module
1

I’m trying to use UAC for audio with EG25 LTE module. I enabled UAC with the following two AT commands:

AT+QCFG=“USBCFG”,0x2C7C,0x0125,x,x,x,x,x,x,1
AT+QPCMV=1,2

It seems Linux detects a sound card 4:

pi@NanoPi-NEO-Core:~$ sudo aplay -l 
**** List of PLAYBACK Hardware Devices **** 
card 0: Dummy [Dummy], device 0: Dummy PCM [Dummy PCM] 
  Subdevices: 8/8 
  Subdevice #0: subdevice #0 
  Subdevice #1: subdevice #1 
  Subdevice #2: subdevice #2 
  Subdevice #3: subdevice #3 
  Subdevice #4: subdevice #4 
  Subdevice #5: subdevice #5 
  Subdevice #6: subdevice #6 
  Subdevice #7: subdevice #7 
card 1: Loopback [Loopback], device 0: Loopback PCM [Loopback PCM] 
  Subdevices: 8/8 
  Subdevice #0: subdevice #0 
  Subdevice #1: subdevice #1 
  Subdevice #2: subdevice #2 
  Subdevice #3: subdevice #3 
  Subdevice #4: subdevice #4 
  Subdevice #5: subdevice #5 
  Subdevice #6: subdevice #6 
  Subdevice #7: subdevice #7 
card 1: Loopback [Loopback], device 1: Loopback PCM [Loopback PCM] 
  Subdevices: 8/8 
  Subdevice #0: subdevice #0 
  Subdevice #1: subdevice #1 
  Subdevice #2: subdevice #2 
  Subdevice #3: subdevice #3 
  Subdevice #4: subdevice #4 
  Subdevice #5: subdevice #5 
  Subdevice #6: subdevice #6 
  Subdevice #7: subdevice #7 
card 2: Codec [H3 Audio Codec], device 0: CDC PCM Codec-0 [] 
  Subdevices: 1/1 
  Subdevice #0: subdevice #0 
card 3: allwinnerhdmi [allwinner,hdmi], device 0: 1c22800.i2s-i2s-hifi i2s-hifi-0 [] 
  Subdevices: 1/1 
  Subdevice #0: subdevice #0 
card 4: EG25G [EG25-G], device 0: USB Audio [USB Audio] 
  Subdevices: 1/1 
  Subdevice #0: subdevice #0

I made a voice call with ATD command and tried to play audio over that sound card with the command:

sudo ./src/tinyalsa/utils/tinyplay -D 4 pcm1608m.wav

However I can’t hear anything on the remote phone.

What’s the problem? Isn’t this the correct procedure?

This is my firmware version:

ATI
Quectel
EG25
Revision: EG25GGBR07A08M2G

OK
2

hi，
Please refer to the document I sent via email.

3

You sent me an Application Note in chinese language. Anyway I found the english version.

I followed exactly what is written in that Application Note, except the kernel source changes. I think newer Linux kernels are already updated, indeed, as I already wrote in my original post, the USB soundcard is correctly detected.

After some tests, I upgraded the firmware version to EG25GGBR07A08M2G_30.202.30.202 and now it seems working well.