[Solved] I2s or Left Justified

Help and Support Help
1

Just a couple of quick questions from a rank beginner. Does the I2s driver from Volumio output a left justified I2s signal? What difference would you hear (if anything at all) if you had your DAC strapped wrong? And last, what I2s driver is running on the beaglebone black, or is it in the kernel?

Thanks for your patience
dsfraser

2

Answering my own question. It appears that the BBB & Pi I2s drivers send the stream in I2s (philips format). My DAC (cheap ES9023) has a solder pad on the underside for I2s or Left Justified (default I2s). Changing this does not kill the music, but reduces the volume, clarity and depth (subjective I know).

At first the volume reduction seemed a good thing as at 100% in Volumio, everything on my system is hammered into clipping.

Aside from using the software mixer is there anyway to reduce the volume limit?

Thanks

3

Sudo alsamixer and reduce output level :wink:

4

Michelangelo:

Thank-you for the reply, unfortunately I’m running Volumio 1.4 on a BeagleBone Black with an I2s DAC. So alsamixer just comes up with the TI BeagleBone Black for an audio card and a “This sound device does not have any controls” notice. So no master volume adjustment. If I attach a USB sound card alsamixer will find that and allows me to change those settings.

Is there perhaps another config file that I can set master volume in? Using the software mixer I am able to use a mpd volume command to set the boot up volume at 70, stored in etc/rc.local. But it would be nice to run without any mixer.

Thanks for taking the time

5

Can you point me to the pinout for pulling I2S from a BBB?

Thanks!

6

Here is what I used

SPI1_CS0 - P9_28 - Bitstream
SPI1_D0 - P9_29 - Left/Right clock
SPI1_SCL - P9_31 - Bit clock

This is for an asynchronous (no master clock) DAC setup, like the PCM5102 or ES9023 (with crystal)

Here are a very informative link if you haven’t seen it

element14.com/community/comm … ding-a-dac

good luck
Douglas

7

Douglas, this wiring works, thanks! Can you confirm what “modules” I would want to load? I’m actually using a PCM1794 chip, but it is “plain I2S”, no I2C needed.

8

Not sure I understand what you mean by ‘modules’. If you are using Volumio and the beaglebone black to an I2s DAC, then the only Audio Output selection will be ‘Black’. The BBB on board chip, at that point it has no idea what I2s DAC you are running.