USB audio on PYNQ-Z1

[tara901]

Hi there, I am pretty new to using the pynq-z1 board. I wish to do some audio recording via a usb microphone! I am struggling with doing this successfully, is anyone able to help me with this?

I am getting "no soundcards found" when issuing alsa commands arecord -l and aplay -l. I understand pynq -z1 receives audio samples as PWM or PDM, but im not sure exactly what that means in terms of linux drivers available. 

any help would be appreciated!

Thanks

[Ciprian]

Hi @tara901,

I need to know some more info before we go further. What Linux are you using on the target and where did you get it?

What USB-Mic are you trying to use?

-Ciprian

[tara901]

Thank you so much for your reply!

Im using 4.19.0-xilinx-v2019.1. I downloaded the image for the pynq z1 v2.5 from http://www.pynq.io/board.html. 

I am currently using the Ugreen audio adapter seen on amazon here: https://www.amazon.ca/UGREEN-Universal-Headphone-Microphone-Raspberry/dp/B01N905VOY.

I am trying to feed the pynq z1 board audio from my phone via a 3.5mm extention cord connected to my phone at one end and the ugreen adapter at the other. This is in turn to the z1 via usb. 

[Ciprian]

Hi @tara901,

Depending on what your end goal is you will have to enable the CONFIG_SND_USB_* (most probably CONFIG_SND_USB_AUDIO, but I can't be sure because I don't own your adapter to test it out) or the CONFIG_USB_AUDIO in the Linux kernel. Both require ALSA and USB to be active in the kernel.

I won't go in to details on what either the CONFIG_SND_USB_* or CONFIG_USB_AUDIO does, the best place to read up on it is on the ALSA wiki where you can find more details about what they are. I must warn you here, ALSA is very finicky, it might not work as expected from the begging.

Unfortunately I have no experience with the pynq platform and I can't guide you trough the process of changing the kernel configuration and rebuilding the image. The best I can do is tell you that you will probably need petalinux for it (you need to look up which version on the pynq site) which runs on certain distributions of Linux ( I personally only used Ubuntu  so far for petalinux). Beware, not all petalinux versions run on any version of Ubuntu. After finding the right petlinux version which you need look up the corresponding Linux distro in the UG1144 of the petlainux version in question.

As for how to make changes to the pynq kernel please refer to the pynq platform support for help or maybe they have a guide on their doc. site.

Good Luck

-Ciprian

[tara901]

Thank you so much for youre help, I figured this was the proper course of action! I was trying to avoid rebuilding the image as I havent done that before ?! Thank you again

!