XMOS-based Asynchronous USB to I2S interface

[Lorien]

Thank you Blitz for confirming the delivery! Regarding the 3.3V supply, I would suggest to use a separate one (something like Paul Hynes, Belleson, etc) and placed it as close to the isolator as possible (with short wires!). Moreover, make sure that I2S connections have the same length and are as short as possible. Feel free to use external USB input @ J1 and move WaveIO close to your DAC board to achieve this.
Cheers,
L

[henri47]

Hi Blitz,
you can use 3,3V for the isolator chip, but 5V will work without any problem.(See notes of Lorien in the mail he sent when the board has been shipped.) I took the 5V on the power header of WaveIO and connected it to the isolator. Works flawlessly.
kind regards,
Henri

[hochopeper]

By connecting a single 5V supply to both XMOS and the isolator chip you don't have isolation anymore and you should really check that your DAC is going to be tolerant of the 5V logic ...

[Blitz]

It is working all nicely...just burning in...need some time...alone the V-Caps shall be burned in 500 hours...so let's be patient...

one question: Can the Buffer size / latency of the Asio-Driver be changed ? And how ?

[henri47]

@hochepeper:
I quote WaveIO manual:

J6 Header is for isolated I2S output signals:
The NVE's IL715 isolator accept 5V or 3.3V power supply on the V+ pin to work accordingly (please see the bottom of the card). DT = I2S Data, LR = I2S Word Clock, BC = I2S Bit Clock, MC = I2S Master Clock. There are also 5 pins dedicated to isolated GND. It should be used.

Is it better to take 5V from placid or 3,3V from BIII to get isolation, or what should be the best solution?

[hochopeper]

@henri47

The voltage seen on the isolator chip V+ pin will be used as the logic 'high' state. So first thing to check is if the BIII ess9018 chip tolerant to 5V logic? I haven't got a BIII so you'd be best consulting the ESS datasheet for that answer. Most I2S lines are 3.3V from my limited experience.

Ideally you would have a separate 3.3V regulator for the NVE chip.

You may be able to get away with using the 3.3V from BIII without too much compromise but I'm not sure what else the 3.3V regulator(s) is supplying on that DAC, I know they supply multiple parts of the es9018 chip from a trident single shunt regs on that DAC but I haven't looked in enough detail to know which parts are combined.

[henri47]

Thanks. My BIII DAC needs TTL level signals on his inputs. I'm using the DAC with the WaveIO card in the way I described in post #922. At first I used the micro BNC connectors, but due to the vulnerability of these tiny conductors I now use the isolated I2S chip on WaveIO. Both seems to work without any problem with the same sound quality. To get isolation would it be best to power the NVE chip with his own PS and own transformer?
kind regards,
Henri

[Lorien]

@henri47: hochopeper is saying better than me. Even if I have a copy of ES9018 datasheet I can see in "Absolute Maximum Ratings" table that you can apply max 5.5V on 5V tolerant pins. Well, I didn't find yet which are those pins! From my experience with other chips, it should be the data input signals (in ES9018 case) but, for the sake of safety, I would suggest to take a separate 3.3V regulator and feed the output side of isolator with it.. using short wires.
Cheers,
L

[henri47]

Hello Lucian,
should that regulator be connected to a dedicated PS or can I take the 5V from the placid shuntreg, but not from power input of WaveIO?

[Lorien]

Whatever is the best (from SQ point of view) Anyway, for testing purposes I would start with Placid. A separate PS (trafo + rectifiers + caps) will be overkill for the moment but you can try it later if you wish!
I do not know Placid very well and where is connected in your system but make sure that this new 3.3V reg will not kill it by sinking too much current.
Kind regards,
L