EC21-AUX UAC ALSA Failure - cannot set hw params: Invalid argument

Technical Subjects Upgrade/Debug
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1

Hi,
With UAC enabled I have the soundcard in place but accessing it via tinyalso or aplay/arecord is not possible.
FIRMWARE: EC21AUXGAR08A07M1G
OS: Debian 12
Kernel: 6.1.0-27-amd64 #1 SMP PREEMPT_DYNAMIC Debian 6.1.115-1 (2024-11-01) x86_64 GNU/Linux

1.AT+QCFG=“USBCFG”,0x2C7C,0x0121,1,1,1,1,1,0,1
RESPONSE: OK
2.cat /proc/asound/cards
RESPONSE: 0 [EC21AUX ]: USB-Audio - EC21-AUX
Quectel EC21-AUX at usb-0000:00:14.0-6, high speed
3. tinyplay test.wav -D 0 -d 0 -c 1 -r 8000
RESPONSE:failed to open for pcm 0,0. cannot set hw params: Invalid argument
4. aplay -L
RESPONSE:hw:CARD=EC21AUX,DEV=0
EC21-AUX, USB Audio
Direct hardware device without any conversions
5. aplay -D hw:CARD=EC21AUX,DEV=0 test.wav
RESPONSE: Playing WAVE ‘test.wav’ : Signed 16 bit Little Endian, Rate 48000 Hz, Stereo
aplay: set_params:1358: Channels count non available

Non UAC audio works but I am having a hard time controlling the amplitude in and out (very high and distorted).

I have upgraded the firmware to this version hoping it would solve the issue as it had for a user with an EC25 in a previous forum post but it hasn’t helped me.

Any help or suggestions would be appreciated. Thanks!

2

at+qdai=3,0,0,5,0,1,1,1
→ Set the freq to 16K. it would take effect after reboot.
aplay -D hw:2,0 -c 1 -r 16000 output.wav

3

Hi,
Thanks but I end up with the same outcome.
+QCFG: “usbcfg”,0x2C7C,0x0121,1,1,1,1,1,0,1
+QDAI: 3,0,0,5,0,1,1,1
AT+CFUN=1,1

cat /proc/asound/cards
RESPONSE:
1 [EC21AUX ]: USB-Audio - EC21-AUX
Quectel EC21-AUX at usb-0000:00:14.0-6, high speed
aplay -D hw:1,0 -c 1 -r 16000 test.wav
RESPONSE: Playing WAVE ‘test.wav’ : Signed 16 bit Little Endian, Rate 48000 Hz, Stereo
aplay: set_params:1358: Channels count non available

tinyplay test.wav -D 1 -d 0 -c 1 -r 16000
RESPONSE:
failed to open for pcm 1,0. cannot set hw params: Invalid argument

Also did a power cycle of the power with the same results.

4

Have you connected with the ALC5616 CodeC with the EC21-AUX?
Please refer to the guide of the UAC, you need to enable the UAC
AT+QPCMV=1,2

5

With running at+qpcmv=1,2 I still have the same outcome.

Welcome to minicom 2.8

OPTIONS: I18n
Port /dev/ttyUSB3, 14:02:08

Press CTRL-A Z for help on special keys

OK
at+qpcmv?
+QPCMV: 1,2

OK
at+qcfg=“usbcfg”
+QCFG: “usbcfg”,0x2C7C,0x0121,1,1,1,1,1,0,1

OK
at+qdai?
+QDAI: 3,0,0,5,0,1,1,1

OK
at+qpcmv?
+QPCMV: 1,2

OK

cat /proc/asound/cards
0 [PCH ]: HDA-Intel - HDA Intel PCH
HDA Intel PCH at 0xa1130000 irq 133
1 [EC21AUX ]: USB-Audio - EC21-AUX
Quectel EC21-AUX at usb-0000:00:14.0-6, high speed

aplay -D hw:1,0 -c 1 -r 16000 test.wav
Playing WAVE ‘test.wav’ : Signed 16 bit Little Endian, Rate 48000 Hz, Stereo
aplay: set_params:1358: Channels count non available

On the main board sound card it plays no problem - as a differential
aplay -D hw:0,0 -c 1 -r 16000 test.wav
Playing WAVE ‘test.wav’ : Signed 16 bit Little Endian, Rate 48000 Hz, Stereo

6

test.wav is 48K not a 16K wav file…
The UAC is working when you make voice all.

7

UAC is not working on voice calls on this machine.
But…
I have moved the modem to a complete different machine, with a later compiled kernel and aplay works correctly to the UAC.
I will further my investigation as to hardware differences as the original machine is an ASUS NUC i7 and that has a lot of USB modifiable options, BIOS wise.
The other machine is also an ASUS MB but a standard ATX with i9 CPU.

I will update on my findings.
Thanks for the help.

8

Is there another application that has already opened the Audio device?
Maybe you can check

lsof | grep pcm

9

It appears to be an inconsistency in ALSA API to the asterisk module I’m using on snd_pcm_open.

I need to put some time into but have been pushed to a different project for a period.
Hopefully in a few weeks I’ll get to check more and will report here.
Thanks for the help, in the meantime.