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What is the Cirrus Logic device name in the Raspberry PI ?

balearicdynamics

After installing the Cirrus Logic Audio Card with the raspian special distribution for realtime kernel there are some tools and scripts for audio management on the Raspberry PI. Then under the /dev there is the /dev/snd folder that includes some components that seems referring to the newly installed audio card.

 

But I need - if possible - to access to the audio features directly using the /dev/<device name> assigned by the system. But I have not found any kind of documentation about the in-depth details on this device. So someone knows how this is installed and set ?

 

Thank in advance. Enrico

  • 0

    There are pdfs which detail the registers used to configure the card, but there is nowhere near enough information to write your own configuration program. Sometimes multiple commands appear in one register and other commands are spread over two or three. I wanted to change the centre frequencies of the equalisers, but there was no correlation between the default frequencies and the registry contents (even after extensive spreadsheet manipulation of the data). As another example, one can get the contents of the DSP default code registers, but there is no information to help one attempt one's own DSP programs.

     

    The patched kernel provides a driver that appears in alsamixer. Run alsamixer in Terminal and you will see all of the switches and controls in an ncursor interface. F6 allows you to select the desired audio device. There are about 400 different controls.which is why the alsa mixer GUI does not work with the Cirrus Logic card.

     

    Read the man pages for amixer to work out the command-line configuration text. Be warned that the labels appearing in alsamixer are often not the text required by amixer. There are amixer commands to list each control, the range of values, whether values are 'paired' and the enumerated number that relates to the text labels. The scripts give a good clue on how to configure the various settings in the card, but the only way to configure the card from your own program is to use a command-line API in your chosen language.

     

    I have written a GUI in Python which you can download from GitHub and which may give you some ideas for your own coding exercise. It uses the Python command-line lib to pass the 'scripts' to amixer. I have avoided the simple mixer commands as they have some limitations. Unfortunately, the Python alsa mixer lib is based on the simple controls which are inadequate for full board control because they fail to deal with large numbers of enumerated settings.

     

    git clone https://github.com/royleith/wolfmixer.git

     

    Look for my Comment 13 at,

     

    A lot of Playback items!

     

    which gives more information on the download.

  • 0 in reply to royleith

    Hello Roy,

     

    many thanks for the explanation. I launched amixer and .... impressive !!! something near to be impossible to understand. Sure you have more experience than me, and my problem is strange yet probably simple but not obvious. As far as what I know, at least.

     

    I have installed in the B+ system with the CL card (and the dedicated distribution of raspian with real-time kernel) the festival suite. Don't know if you know it, it is a good speech synthesis system, a bit wide but with good voices and good parameters for any kind of settings.

    To install is I had to recompile the entire suite and reconfigure the speech system as it is almost impossible to install anything from the repositories due this version of the kernel that can't be upgraded.

     

    When I run Festival, the problem is that is search for a audio device under the /dev/... folder (a configurable parameter) and I have no idea of what is the real device I should point to. As I mentioned in my previous post there is only a couple of things under the /dev/snd and /dev/snd/by-path but as I set these (tried with all) in the festival configuration no error is generated but no sound too... This is what sounds strange to me.

     

    Anyway all the information you have collected and organised in your work are really great ! I should analyse them in details, especially the python work that seems really good.

     

    Thank for your time. Enrico