Hello All I have a question/problem..
I am running the Cirrus Logic Audio Card with a Raspberry Pi 2b
I want to use the rpi as a digital filter. Therefore I use pyaudio to open a stream and within the callback function to filter.
Right now I have the problem that after around 5 seconds I get an "ALSA underrun occured" error, could you imagine how this is possible? Or how do I create this error? Checked it with an audio analyzer (at my university) the filtering works but only for a few seconds...
Trying to google underrun occured raspberry didnt bring up any clues...
As you might know, Cirrus Logic's main kernel source branch recently switched to 3.18.
My first thought was "Hmm, that means the Cirrus Logic card could finally work on the RPi2..."
I have built a couple of 3.18 kernels for my B+ and RPi2 and I have managed to get both models to produce sound
It's still early days, i.e. there are possibly bugs and glitches to fix, but for those of you who would like to try it out I've made an image file that you can download here:
The file is a 1.3 GB zip. Uncompressed size is 3.1 GB, so it fits comfortably on a 4 GB card.
The image is based on the standard 2015-02-16-raspbian-wheezy image from the Foundation that you flash to a SD card for a fresh install.
I have only added my kernels and set up the configuration files to get the card going.
It should work on the older B model with a Wolfson Audio Card too, but I haven't tested that yet.