Asynchronous I2S FIFO project, an ultimate weapon to fight the jitter

You see, I find the deserving and somewhat lazy attitude of 'diyers' like yourself rude and you have just reinforced that by your juvenile response to me and Chris because he dared to feel the same way. Out come the slurs and silly patriotic guilt trips. We both bit our tongues yesterday and other days before that, I couldnt do the same again today.

to expect others to take the time out of their lives to spoonfeed you when the answers are right in front of you gets old pretty fast. You choose to repeatedly just type out questions to the oracle, now that is rude. I wont attribute this to your country of origin, its all over this forum and others like it in todays world. treating the internet forums and their members like they are some personal magical interactive time and money saving mechanism instead of people with the same constraints on their time as you have. if you behaved that way at work you wouldnt last long would you? Certainly nowhere i've ever worked.

if you dont understand a concept, the information is as freely available on the net to you as it is to anyone else. I'm not trained, i'm a Chef and designer by trade; I had to/have to learn by reading and doing, yes by asking questions along the way, but you have to show you are willing to do something. In this thread and those all over the forum, or in life, if you continue to show no initiative and just keep putting your hand out, people will get sick of it and yes some of them will let you know about it; i'm one of those people.

I/We get sick of having to hold peoples hand when they take on projects that are beyond their current knowledge, yet seem unwilling to do any work of their own to grow their understanding.

you will get nowhere doing DIY if you cannot take some initiative, read datasheets and manuals, google galvanic isolation, understand the questions you are asking and try to find out yourself before expecting it to be handed to you, you learn nothing in that process. then because you havent equipped yourself to better understand next time, you just ask for the answer again with the next thing and again walk away having learned nothing. If something goes wrong (quite likely) you will not be equipped to figure out what went wrong; then the forum will be expected to come to the rescue, like its something owed to you.
Take a look at this guy's detailed description of me. qusp, you seem to think you know all about me based on my asking a few polite questions and making a couple of suggestions. You chop the world around you up into an inappropriately limited set of categories and you're *absolutely* sure everything you see *must* fit into one of your categories. After all, you know everything, right? Square peg in a round hole... wow... you said it best yourself.

And if condescension is justified when someone fits into your category outlined above, how do you explain the same attitude when they don't? This entire thread is peppered with your rude remarks in every type of discourse. I'm actually receiving PM's from other members about you. Let's just say I speak for a lot of people when I suggest you stop polluting the forum with the fallout from your emotional dysfunction.

haha you clearly dont know many Aussies. Smiling up to a point.... i'm just not shy to say what others are thinking, rather Aussie trait that one. To 'call a spade a spade' so to speak. I suspect you have only seen us on television
"haha" indeed. Just another example of this guy stuffing everything he sees into one of his categories. qusp, several times I've been all over the glorious continent you're fortunate enough to call home and I'll be back this month. What to do? Widen a category or create a new one? Choose fast or your whole world will fall apart.
 
Ian, thank you for the information and thank you for sharing the benefit of your hard work. In the future I will think carefully about how to research a question before I post it here. As I said before, this thread is clearly geared toward experts and you all should have a place to discuss things without being bothered by trivialities.
 
As a starter, I want to add my point of view since it doesn't seem to be represented.
When I see the type of responses from people like ggking7 I feel a bit ashamed.
I found these answers more arrogant than qusp's.
I am at the begining of this fantastic trip of diy. I try to go step by step.
Sometimes I feel I need someone who can help me.
But here we heve everything we need to do our homework.
I respect people with the knowledge, as the needer I have to respect their way and make them do what I want or need. That is the base of respect between student teacher.
Now people don't care about this, everything on interent is free, so people think others people owe them.
I recognise that I did ask questions I coud have answered myself if I have done my homework.
And so ? If someone tells me to search by myself, I think it is true and I respect that. I will try to refrain to spurt my anger to others, it is my responsability.
That is the way to learn, to grow and to become experienced.
Even if qusp is dry, I think is a lot more honest than the shameful responses from " a group of users" given by ggking7.
With these kind of answers I feel ashamed to be on the beginner side.

But anyway, thanks, as it is a good opportunity for me to be honest with myself, recognizing some behavior I could have, and most important trying not to reproduce it. In other words, apart from diy, the community is the opportunity to work on my ego !

I hope my point, not expressed by others will give others some reflexions.
And it is not a debate, I share my own work to inspire other like I was inspired by the work of others.
 
I'm going to try very hard to make this my last post on the subject. qusp will reply and I will try to leave it at that.

There is an emotional response which is triggered in me when I go back through this thread and see that qusp has a history of terrorizing people. It started long before I showed up and it frequently isn't associated with anyone asking a question. It is OK to stand up for yourself and it is OK to call out condescension in the face of a bully, online or off.

qusp will take his turn and I hope that will be the end of it.
 
actually no, I said what I needed to say, clearly you dont get it now and with your attitude, unlikely ever will. I think i've got a pretty good handle on you from the last couple of months. all I need, or want to know.

terrorize lol, wuss

have a nice life, welcome to my ignore list
 
Resistor SMD pitch on SPIF input board

Hi Ian,

What's the SMD pitch of R42-R44, R46? They appear to be 0603, but want to make sure. They're a bit big for panel mount LED's as they'll squeeze out just 1.6mA, not quite enough for the LED's I'm using. I'm hoping to use about 620 ohms there.

Thanks,
Gary
 
Hi Ian,

What's the SMD pitch of R42-R44, R46? They appear to be 0603, but want to make sure. They're a bit big for panel mount LED's as they'll squeeze out just 1.6mA, not quite enough for the LED's I'm using. I'm hoping to use about 620 ohms there.

Thanks,
Gary

They are 0603. You can reduce those resistors to get bigger LED current. Schematics of this section posted in previous post. 620ohm is OK. How much current will be up to what kind of LED you are using. Try to use resistors as big as possible to reduce power consumption.

Ian
 
They are 0603. You can reduce those resistors to get bigger LED current. Schematics of this section posted in previous post. 620ohm is OK. How much current will be up to what kind of LED you are using. Try to use resistors as big as possible to reduce power consumption.

Ian

It's difficult to find very efficient panel LED's at 2mA. I think it relies to a large degree on a tight dispersion angle, DK had just one (3mm) less than 40 degrees. In any case, the LED's I've selected are bright enough at 2mA; to get that requires a 620 ohm resistor with the 3.3V supply.

Thanks,
Gary
 
I need my crazy pills :eek:

Me too. Its amazing how we can pick a GMR designed for TV's to prevent failures and think it has anything to do with audio quality.

I think we want galvanic isolation in audio for a different reason than most other applications. We want it to prevent ground bounce from interferring with the digital to analog conversion. I don't see how a GMR can do that since this GMR duplicates the EMI it sees on both sides of the ground up to 110MPS.

Best bet with the FIFO is still to use the SPDIF board in front of it, the addition of the GMR board isn't going to change that IMHO. Interesting attempt though.
 
Regardless of isolation on the input there is still some benefit in further attenuation of the EMI generated by the FPGA.

Yes there are EMI filters on the board but an isol board like Ian has presented seems logical in this application unless I've missed something.

edit: heh I missed seeing qusp's post before I wrote this.
 
Correct me if I am wrong but a GMR as spec'd here (IL260E) works a lot like a little transformer. They provide galvanic isolation and these at 110mbs transmit EMI, to both sides of the taps.

Believe me I wish I was wrong but the isolation board would really just stop current surges not EMI to the ground plane. I am just looking at the physics.
 
Correct me if I am wrong but a GMR as spec'd here (IL260E) works a lot like a little transformer. They provide galvanic isolation and these at 110mbs transmit EMI, to both sides of the taps.

Believe me I wish I was wrong but the isolation board would really just stop current surges not EMI to the ground plane. I am just looking at the physics.

My understanding is that the isolator chips each work slightly differently but for sake of convenience that is how we generally chose visualise their operation.

If we continue with that visualisation then I believe that the efficiency of the high freq noise transmission is not going to be perfect. We could visualise this lack of high frequency efficiency as a low pass filter I guess. It is for this reason that we often associate GMR with adding jitter, isn't it? So we select a GMR that is able to pass sufficiently high frequencies that the data is cleanly passed, but noise at a higher frequency may be attenuated. We then are able to rely on EMI filters applied by Ian in his design for addressing the lower frequency EMI (they may also address higher freq too, but higher the freq the harder these things become to address generally speaking) and the GMR may eliminate some of the higher frequency noise created by the transport and FIFO FPGA chip.

No one has tested these yet. No one has said they will change the world of digital music as we know it. It is simply an experiment to try to squeeze the last peice of musical juice from the digital data-stream. Considering that by the time a transport, dac and IV are to the stage of development and integration comparable to the FIFO design, we're generally well past the point of diminishing returns. This, in my opinion, is a nice experiment that may allow the last 0.5% or so of improvement, for a lot less money than other improvements that many are making.

I for one am interested to see the outcomes!
 
I have to say the isolator is really working for my system, especially followed by a re-clock stage(to eliminate additive jitter from isolatro board, but MCLK still local always:) ) . This is not a new technology, we could find it in many high precision high speed data acquisition system. It even being widely used in medital electronic system. They made signeficant improvement to the uV level medical signal processing performance beasuse of the isolation of common mode and EMI noise, as well as the safty.

Ian
 
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Just some digital audio solutions from TI application note for reference:

"Figure 11(b) shows an improved method for high performance,
mixed signal board layout. This method adds digital
isolation between the DF1704 and the audio DACs, and
provides complete isolation between the digital and analog
sections of the board. Texas Instrument’s ISO150 dual
digital coupler provides excellent isolation, and operates at
speeds up to 80Mbps."

Ian
 

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