Matrix Voice and Raspberry Pi Zero Audio output


i have a question regarding the audio jack on the matrix voice…
Since my raspberrypi zero doesn‘t have a audio jack, i would need another way to output some audio.
I thought it must be possible via the audio jack from my matrix voice.
I searched the community and read that it can be done, but i did not find a way to configure this.

I want to use my magrix voice as a mic and as a speaker output for my raspberry pi.
Is this possible?

Thanks in advance for your help.

Yes that audio jack in the MATRIX Voice is for audio output. Currently is not currently working because we are checking some bugs in the the Kernel Module playback section and what is released now doesn’t support playback. So, stick around and wait for the fix. We know this a important feature for users.


Ok, thank you for the update and your hard work :slight_smile:
Please inform me when you have a release version for that feature.

how long do we have to wait for the fix?the function was promised a long time ago.


I’m waiting this fix too…please try to solve this problem as soon as possible.

I think buying a respeaker and tell all friends they want to use matrix Voice that they never get the promised features.


Hi @joeduck

Sorry for the delay.

The Pull Request for audio output has been merged into our dev branch and should be officially released later today.

Thanks. But why you let the customers over one year waiting? However. now we have the feature and hope it works.

I do a update today, but have this error. So no updated Matrix Kernel Modules where installed. Can you tell me what is wrong?

Unpacking matrixio-kernel-modules (0.1.4) over (0.1.4) …
dpkg: error processing archive /var/cache/apt/archives/matrixio-kernel-modules_0.1.4_armhf.deb (–unpack):
unable to make backup link of ‘./boot/overlays/matrixio.dtbo’ before installing new version: Operation not permitted

Thanks, Jochen

@joeduck I’ve had this error in the past and yesterday while reinstalling the kernel module package.

In the used to rename the file and update the package…

sudo mv boot/overlays/matrixio.dtbo boot/overlays/matrixio.dtboold

But this didn’t work yesterday so I had to purge the kernel module, reboot and install the kernel module again.

There were several updates on GitHub so audio out is happening!


If you need any help testing audio out via the speaker connection on the marrix voice let me know. I bought the speaker connectors from digikey, updated the kernel modules and am curious about the configuration to get this going.

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Thanks! Now the Modules are loaded and the sound is working.
My Speaker config in the asound.conf:

pcm.speaker {
  type plug
  slave {
    pcm "hw:2,1"

Does the noice cancellation work? Can i Play music over the matrix and talk to the mic?

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Hi @joeduck,

Glad to hear that.

My guess is you are referring to AEC ( Acoustic Echo Cancellation). We currently dont offer any AEC examples but you could use 3rd party libraries for this like SpeexDSP or WebRTC.


Regarding the last update on the kernel module about the audio playback, we will share a more official guide on the documentation, but to test it you just need to install the kernel-modules package :

  • Follow steps for Option1: Package Installation.
  • After reboot download some audio in wav format:
    wget -O ./audio-sample.wav
  • Connect headphones or a peaker via the 3.5mm jack in the MATRIX Voice board.
  • and play it using:
    aplay -D "hw:2,1" ./audio-sample.wav

Let me how it goes.


Hi yoel, will this be implmented in the esp32 as well?
I am currently stuggling with bluetooth (more accurate the resampling of audio because of limitations in the esp framework)

Yes @Romkabouter, we will be also releasing a example/demo playing audio from the ESP32 based on this code. If you can’t wait for the official example, you can give it a try and share your feedback here if you want, that code should be almost working :). I think the use of HAL code is in the bt_app_av.cpp file.


Great! I will try it as soon as I can get my hands on it :smiley:
Nice to see you have a BT sink demo as well! I was referring to using the esp32 as a a2dp source by the way :slight_smile:

@yoelrc88 I bought the speaker connectors here…

Do you have any directions for outputting audio on this interface?

I remember that the audio_demo had an option to define either headphone or speaker before compiling.

FYI, audio out via the 3.5mm jack works well if the audio was recorded with the right sample rate.

Thanks for all the work you have done.

can play .wav files with aplay and mp3 files with mpg123. Have Output on the 3.5 mm Jack of the matrix voice. But no chance to adust the volume. and courios: no sound from snips output. But “sam test speaker” give sound. going back to the raspi Jack snips output works.

Canm i play music on the matrix audio jack an speak to the mic? On respeaker this works cause the internal AEC.

We currently don’t provide AEC for MATRIX Voice, you will have to use a 3rd party library or software, like SpeesDSP or WebRTC.


This is from your website. One Reason why I bought the matrix voice. What should I do with the audio jack when AEC is not working? Then I can use the raspi audio…

 Spartan-6 FPGA

Leverage fast audio processing and advanced algorithms for voice. Beamforming, AEC, de-reverberation and noise cancellation.