Hi,
I2S is a standard for digital audio, originally made by Philips and Sony back when they put together the CD format. It's pretty straightforward. A word clock starts out 0 for the left sample, then goes to 1 for the right sample. Digital data is transferred MSB-first on the edges of the bit clock. The number of bits may be almost arbitrary, since a DAC stops latching after it has received its share of bits for its resolution. The tricky bit about I2S is that it's synchronous with music, and more importantly that a "dead tick" occurs after a word clock edge, before the MSB of the next sample. To make things more complicated, if all bit clock ticks are needed to convey audio samples (what I call "bumper-to-bumper" I2S), the LSB of the previous sample is transmitted during the "dead tick".
What this boils down to is that I2S is straightforward between audio equipment which has it enabled, and a major hassle for MCU designers who try to fit it into existing serial port hardware.
I expect built and tested hardware in about two weeks, crossing my fingers that everything works out.
Cheers,
Børge
I2S is a standard for digital audio, originally made by Philips and Sony back when they put together the CD format. It's pretty straightforward. A word clock starts out 0 for the left sample, then goes to 1 for the right sample. Digital data is transferred MSB-first on the edges of the bit clock. The number of bits may be almost arbitrary, since a DAC stops latching after it has received its share of bits for its resolution. The tricky bit about I2S is that it's synchronous with music, and more importantly that a "dead tick" occurs after a word clock edge, before the MSB of the next sample. To make things more complicated, if all bit clock ticks are needed to convey audio samples (what I call "bumper-to-bumper" I2S), the LSB of the previous sample is transmitted during the "dead tick".
What this boils down to is that I2S is straightforward between audio equipment which has it enabled, and a major hassle for MCU designers who try to fit it into existing serial port hardware.
I expect built and tested hardware in about two weeks, crossing my fingers that everything works out.
Cheers,
Børge
Thanks for answering now i know something...so if all goes well...what parts you recomend to buy(DAC+USB -I2s) ....MY pc is following...
http://www.diyaudio.com/forums/pc-based/215731-pc-music-transport-25-a.html
V
Hi, just to ask if any body here has, by any chance, these three devices: an Ipad + Camera connection + USB DAC QNKTC
I'm curious to see if it works this DAC with Ipad as a source. Some DAC's do, but I'm afraid it has to be not self powered DAC... but I haven't seen much about it.
Here is a link with the discussion:
List of DACs that work with iPad
Thannks
I'm curious to see if it works this DAC with Ipad as a source. Some DAC's do, but I'm afraid it has to be not self powered DAC... but I haven't seen much about it.
Here is a link with the discussion:
List of DACs that work with iPad
Thannks
I think you misunderstood the site you linked. Many DACs will work with self-power.
By the way, in USB terminology, "self powered" means external power. "bus powered" means USB power, i.e. from the iPod dock.
Ordered and now waiting...
V
Just want to make sure this works with Limux...will be using puppy linux MPD....
Hi thanks for correcting... sorry.
What I mean is something like this:
http://www.head-fi.org/t/491308/ipad-with-udac
http://www.flickr.com/photos/nokton/4621172765/
I don't understand what type of bus powered DAC is needed to connect with an iPad via camera connection kit. The pictures from flickr is exactelly what I what out from QNKTC DAC... if possible.
What I mean is something like this:
http://www.head-fi.org/t/491308/ipad-with-udac
http://www.flickr.com/photos/nokton/4621172765/
I don't understand what type of bus powered DAC is needed to connect with an iPad via camera connection kit. The pictures from flickr is exactelly what I what out from QNKTC DAC... if possible.
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More info:
The widget has the latest code as of 20120519 and is a pcm5102 type by George. I finally got a machine with Win7 and the WidgetControl seems to work every time
I dont have this issue with Georges 9023 or Börges AB-1.1 (older code).
Brgds
BTW: What is the difference with latest and main firmware versions? The size has jumped up considerably lately...
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Our ASIO uac2 driver by Nikolay supports 44.1/48/88.2/96/192. 176.4 is disabled at the moment. I think Nikolay is keeping that for DSD in future.
Alex
More info:
The widget has the latest code as of 20120519 and is a pcm5102 type by George. I finally got a machine with Win7 and the WidgetControl seems to work every time
I dont have this issue with Georges 9023 or Börges AB-1.1 (older code).
Brgds
BTW: What is the difference with latest and main firmware versions? The size has jumped up considerably lately...
Accidentaly used usbi2s instead of usbdac - works now in uac2 mode and I suspect uac1 will work as well!
Brgds
Ground isolation - we need it!
Interesting measurements (on another USB/I2S interface) showing the importance of GND isolation:
exaU2I - Multi-Channel Asynchronous USB to I2S Interface: Ground isolation - with and without
Interesting measurements (on another USB/I2S interface) showing the importance of GND isolation:
exaU2I - Multi-Channel Asynchronous USB to I2S Interface: Ground isolation - with and without
Indeed. That's why I am eagerly awaiting the next version of audio-widget with i2s isolation
I get suspicious when I see inadequately documented tests. The grounding they used (1Meg resistor?) can cause some USB problems and the measurement suggests there were more than one path between the computer and the audio system. The assumption that removing the ground will make things wonderful can easily be tested by using a laptop on battery. That is as isolated as possible, but there are reports its not enough.
Meanwhile good isolation is not simple. I started on a design to work with the Audio Widget. I'll see if I can find it and share it. The bigger issue is powering the isolated parts.