dai (digital audio interface)

Does anybody knows what is the best way to connect DAI (PCM digital audio interface) which must be master and to connect it to USB ?

Is there any USB chip that have slave DAI on it ?

thanks

Reply to
george
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George,

USB audio devices typically derive their clock from the PC. Either synchronous to SOF, our implicitly via the playback data being streamed. A digital audio interface as a slave to an external clock implies that you are providing a clock to the host PC. Assuming you are talking about a full-duplex device (playback and recording) this is not trivial.

Microsoft did not have proper support for this before Millennium/ XP. Apple did not support this properly before MacOSX 10.4.2. But even if these operating systems are available for a few years now: This is a continuous cause of trouble. We have gone through all of this a few years ago- educating Microsoft and Apple how to implement the USB spec properly. You might remember our hardware:

formatting link

There used to be a couple of chips from Philips Semiconductors implementing I2S to USB or Analog to USB. In case you can still find them (I believe they are EOL), you might add a SPDIF receiver and be done. But look closely at the spec: Check if this is really working

*without* cheasy resampling. If it does involve resampling, there is no real point in being slaved...

With the EMI 2|6 we used a Cypress EZusb and implemented the complete audio data path in a Xilinx FPGA. I am not sure, if your application can afford this. If cost is not the issue, this will lead to a very flexible solution.

Hope this helps, best regards

Felix

--
Dipl.-Ing. Felix Bertram
http://homepage.mac.com/f.bertram
Reply to
Felix Bertram

George,

USB audio devices typically derive their clock from the PC. Either synchronous to SOF, our implicitly via the playback data being streamed. A digital audio interface as a slave to an external clock implies that you are providing a clock to the host PC. Assuming you are talking about a full-duplex device (playback and recording) this is not trivial.

Microsoft did not have proper support for this before Millennium/ XP. Apple did not support this properly before MacOSX 10.4.2. But even if these operating systems are available for a few years now: This is a continuous cause of trouble. We have gone through all of this a few years ago- educating Microsoft and Apple how to implement the USB spec properly. You might remember our hardware:

formatting link

There used to be a couple of chips from Philips Semiconductors implementing I2S to USB or Analog to USB. In case you can still find them (I believe they are EOL), you might add a SPDIF receiver and be done. But look closely at the spec: Check if this is really working

*without* cheasy resampling. If it does involve resampling, there is no real point in being slaved...

With the EMI 2|6 we used a Cypress EZusb and implemented the complete audio data path in a Xilinx FPGA. I am not sure, if your application can afford this. If cost is not the issue, this will lead to a very flexible solution.

Hope this helps, best regards

Felix

--
Dipl.-Ing. Felix Bertram
http://homepage.mac.com/f.bertram
Reply to
Felix Bertram

George,

USB audio devices typically derive their clock from the PC. Either synchronous to SOF, our implicitly via the playback data being streamed. A digital audio interface as a slave to an external clock implies that you are providing a clock to the host PC. Assuming you are talking about a full-duplex device (playback and recording) this is not trivial.

Microsoft did not have proper support for this before Millennium/ XP. Apple did not support this properly before MacOSX 10.4.2. But even if these operating systems are available for a few years now: This is a continuous cause of trouble. We have gone through all of this a few years ago- educating Microsoft and Apple how to implement the USB spec properly. You might remember our hardware:

formatting link

There used to be a couple of chips from Philips Semiconductors implementing I2S to USB or Analog to USB. In case you can still find them (I believe they are EOL), you might add a SPDIF receiver and be done. But look closely at the spec: Check if this is really working

*without* cheasy resampling. If it does involve resampling, there is no real point in being slaved...

With the EMI 2|6 we used a Cypress EZusb and implemented the complete audio data path in a Xilinx FPGA. I am not sure, if your application can afford this. If cost is not the issue, this will lead to a very flexible solution.

Hope this helps, best regards

Felix

--
Dipl.-Ing. Felix Bertram
http://homepage.mac.com/f.bertram
Reply to
Felix Bertram

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