Ever since the Raspberry Pi came out, I’ve been experimenting with its audio capabilities. The latest audio gizmo available for it is the Wolfson Pi Audio Card, which promises 24 bit, 192kHz recording and playback, with analog and digital I/O, for a very reasonable price. So of course I ordered one straight away. 🙂
After waiting a month I finally got my hands on it. The software installation is somewhat unclear so I will document what I did here. I didn’t want to use the Wolfson official image as it was a massive 8GB download. I started with a copy of the image that I developed for PiTunes, and applied this patch to it, which adds the Wolfson kernel and the support files for the audio card. I then changed mpd.conf to use audio output device hw0,0 (it was previously 1,0 for the USB audio device) and added a call to SPDIF_playback.sh in my .bash_login file, to set the card up for digital output.
I also removed the invocation of pikeyd from /etc/rc.local, as the keypad and encoder were not present. They can’t be used anyway, since the Wolfson audio card hogs all of the GPIO pins. It doesn’t really matter, as MPD can always be controlled remotely.
On firing this up, I was surprised to find that it worked first time! 🙂 I verified the output to be bit perfect at 24 bit, 96kHz. This is possibly the best value for money HD audio source you can get anywhere: you should be able to pick up a Raspberry Pi, a Wolfson Audio Card, a wifi dongle and a hard disk for under £100.
I don’t have the exact same setup. I use the stock Wolfson Pi image. But I can’t get the SPDIF out to work. It only does analog out. SPDIF in is fine, so I can record from an ADC. But not out. Any ideas?
Hi John. I assume you ran the “SPDIF_playback.sh” use case script to activate the SPDIF output? If so, I’m not sure what the problem would be.
I noticed that the SPDIF output on the Wolfson card is non-standard. It is just a straight feed from the output pin on the chip, so the voltage will be higher than regular SPDIF. This might be upsetting the receiver. I use mine with the AES input on a Behringer DEQ2496.
I suppose I could hook it up to an oscilloscope.