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XMOS-based Asynchronous USB to I2S interface

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Hi guys,

I was  thinking about developing a in house XMOS-based asynchronous USB to I2S interface. EBay is full of them so I’m obviously not trying to compete in that area but it would be good to have my own version to use in GIESELER products. We could probably do a stand alone version as well which may be of interest for DIY projects. Rather than just a basic unit I was thinking of including full galvanic isolation plus re-clocking on the I2S outputs. Say similar to the Singxer F1 but without the S/PDIF output. The XMOS chip UX208 that most manufacturers are using is the XU208-256-TQ64. It cost the huge sum of $16

& is available from DigiKey.

https://www.digikey.com.au/product-detail/en/xmos/XUF208-256-TQ64-C10/880-1112-ND/5358025

XMOS supply development firmware. I have a good coder so he will handel that side of things.

The main issue will be the Windows USB driver. Thesycon have a free evaluation driver (with the beep) so I need to investigate a production version.

USB-Audio-2.0-Driver-for-Windows---Overv

I have done a few four layer boards laterly, have a new reflow oven & my C++ coder is confidant - how hard can it be?

Well what do you think or am I dreaming!

 

Edited by Gieseler Audio
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Clay, are you aiming for this device to be a replacement for the Amanero384 board in terms of pin-compatibility, or will it be a new configuration altogether?

 

Would I be jumping to conclusions by assuming that you are considering this option after hearing the XMOS 208-based Singxer device and liking what you heard vs the Amanero?

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Clay IMHO there's a few good boards out there and a lot of stuff that's poorly/not completely done or overpriced. 

 

I get what you're looking for, maybe an easier way concerns reviewing a few different parts?

 

I don't think it should be a surprise that the Amanero isn't TOTL, it's not intended to be. There are a few good USB>I2S implementations out there, though.

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Thanks for the input guys.

 

Pete - for my products rather than a plug in board I would probably just integrate it into the main board. That keeps the I2S lines a short as possible & I can have the regulators 

close to where they are needed. I could do a plug in board though if there was enough interest.

Re XMOS vs Amanero - I actually have a Singxer F1 & compared it (Coax out into coax input on Groß) to the built Amanero USB.  The Amanero was better but that is to be expected 

as the F1's  power source is dirty PC/USB in plus the re-clocking & isolators on the F1 are powered by a internal DC DC converter.(noisy) Also the I2S output on the F1 is converted to S/PDIF & then when entering the DAC has to go through another S/PDIF receiver to get back to I2S for the DAC chip. Now straight I2S from XMOS + iso & re-clock would be a different result for sure.

 

Riccardo - Yes I agree even some of the better units never seem to get it totally right. Aside from good regulators I think it would be important to run the "back end" (isolators & re-clocking) 

from a fully independent (galvanic isolated) PSU as well. 

Do you think going to the XU216 would be a worth while improvement over the XU208?

 

 

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Clay, I wouldn't think the 216 offers significant improvement unless you're running out of MIPS, RAM, IO or other; the 216 is essentially two 208's.

 

I'd think the real magic in these things is in isolation, power and reclocking... the last part is significantly understated. There are certainly a few boards out there doing logic-based reclocking that allegedly sound quite good. 

 

You'd have to wonder what licensing an Amanero or similar - something already having the driver done - and building the rest would be worth.

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3 hours ago, rmpfyf said:

Clay, I wouldn't think the 216 offers significant improvement unless you're running out of MIPS, RAM, IO or other; the 216 is essentially two 208's.

 

I'd think the real magic in these things is in isolation, power and reclocking... the last part is significantly understated. There are certainly a few boards out there doing logic-based reclocking that allegedly sound quite good. 

 

You'd have to wonder what licensing an Amanero or similar - something already having the driver done - and building the rest would be worth.

From a non-technical point of view, I have heard feedback on the units that are for sale on DIYHK. He uses the newer 216 chip and I have read (for what it's worth) that the way he's uses the chip does not sound so great (in comparison to the better 208 units) - the reason being - wait for it - power filtering and isolation.

I think a really top implementation of a 208 chip with i2S would grab my attention for sure. I am using my NUC Rock to feed my Direct Stream Junior directly via USB as my ethernet - Bridge connection had too many dropouts. Being able to use the NUC and then connecting the the i2S input (which is the best input that is available on the DSJ) with isolation and reclocking would be a boon for me.

I hope you proceed ;)

 

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