I pretty much followed the official tutorial.
Issue with later versions is that at some point I2S was disabled in favor of PWM working on the same pins.
As soon as you have proper firmware installed you need to issue following commands
install necessary packages opkg update opkg install alsa-utils mpg123 enable I2S omega2-ctrl gpiomux set i2s i2s
Verify that souncard is present
aplay -l**** List of PLAYBACK Hardware Devices **** card 0: AudioI2S [Audio-I2S], device 0: ralink-i2s-HiFi HiFi-0  Subdevices: 1/1 Subdevice #0: subdevice #0
Presense of this device doesn't imply that souncard is working, it will bang I2S pins even if they hang in the air. But to have the sound device listed is a good sign.
Next you test audio with any audio file or stream, I used my local stream here
mpg123 http://192.168.1.42:8000/fgHigh Performance MPEG 1.0/2.0/2.5 Audio Player for Layers 1, 2 and 3 version 1.22.3; written and copyright by Michael Hipp and others free software (LGPL) without any warranty but with best wishes Directory: http://192.168.1.42:8000/ Playing MPEG stream 1 of 1: fg ... ICY-NAME: Fabio & Grooverider ICY-URL: http://www.icecast.org/ MPEG 1.0 layer III, 128 kbit/s, 44100 Hz joint-stereo ICY-META: StreamTitle='ÿþR - ÿþF';
Voila, we have a sound!
- I want to build latest firmware version with I2S support enabled
- I found board hanging on wifi initialisation. I soldered 100uF cap to power pins directly and the issue went away. Now i need to adjust PCB design to have decoupling caps closer to Onion board.
- Today found an article on separating digital and analog grounds, need to try that as well:)