Asynchronous I2S FIFO project, an ultimate weapon to fight the jitter - Page 37 - diyAudio
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Old 15th April 2012, 04:38 AM   #361
qusp is offline qusp  Australia
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so other than clock, only precautionary heatsinking needed along with firmware change to go this high? as far as USB, no I only know of custom solutions that will go this high
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Old 15th April 2012, 07:33 AM   #362
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Originally Posted by kazap View Post
Yes please -I think your FIFO right justified 24bit output plan will be widely appreciated.
......

If you can add USB input it would be perfect for me?

Thanks for your amazing work so far.
Kazap said it perfect, I was just going to post the same things PCM1704 is still in production even though its price is ridiculous and a device like the one we are discussing here will make happy not only people who own 1704 based machines but also people who can design stuff from scratch, I know a few of them I was really hoping the Exa guys will bring a 1704 compatible device to the market but I guess interests were shifted in another direction...
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Old 15th April 2012, 05:11 PM   #363
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Hi Ian,
can I use your FIFO kit from CD PRO I2S to a pair (stereo) of PCM63?
If yes, what I need? 1 I2S FIFO KIT and 1 DUAL XO CLOCK BOARD?
Also, can I interface I2S FIFO with NPC SM5843?

Andrea
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Old 15th April 2012, 06:29 PM   #364
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Originally Posted by andrea_mori View Post
Hi Ian,
can I use your FIFO kit from CD PRO I2S to a pair (stereo) of PCM63?
If yes, what I need? 1 I2S FIFO KIT and 1 DUAL XO CLOCK BOARD?
Also, can I interface I2S FIFO with NPC SM5843?

Andrea
Hi Andrea,
You can feed I2S signal from CD PRO into I2S FIFO. But the output is still I2S. PCM63s do not accept I2S, You need a little converter board which we are talking about. I didn't go deep into SM5843, does it support I2S input?
Regards,
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Old 15th April 2012, 09:51 PM   #365
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Originally Posted by iancanada View Post
Hi Andrea,
You can feed I2S signal from CD PRO into I2S FIFO. But the output is still I2S. PCM63s do not accept I2S, You need a little converter board which we are talking about. I didn't go deep into SM5843, does it support I2S input?
Regards,
Oops.. I wrote SM5843 but I meant SM5842, a digital filter 8-times oversampling (384fs for SM5842AP). I read from datasheet about data format:
Input data format
2s complement, MSB first
- LR alternating, 16/18/20/24-bit serial, trailing
data
- LR alternating, 24-bit serial, leading data
- LR simultaneous, 24-bit serial, leading data
Do you think that I2S FIFO can feed it directly?

BTW if I decide to make non oversampling DAC with a pair of PCM63 I'm interesting to directly interface them.

About CD PRO: I'm planning to build 2 separate box, one for transport and one for DAC, so you say that I can take I2S signal directly from CD PRO. right?
One more question: taking directly I2S data from CD PRO, do I need any reclocking in transport to avoid jitter? Would it be redundant?

Andrea
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Old 16th April 2012, 12:35 AM   #366
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Quote:
Originally Posted by andrea_mori View Post
Oops.. I wrote SM5843 but I meant SM5842, a digital filter 8-times oversampling (384fs for SM5842AP). I read from datasheet about data format:
Input data format
2s complement, MSB first
- LR alternating, 16/18/20/24-bit serial, trailing
data
- LR alternating, 24-bit serial, leading data
- LR simultaneous, 24-bit serial, leading data
Do you think that I2S FIFO can feed it directly?

BTW if I decide to make non oversampling DAC with a pair of PCM63 I'm interesting to directly interface them.

About CD PRO: I'm planning to build 2 separate box, one for transport and one for DAC, so you say that I can take I2S signal directly from CD PRO. right?
One more question: taking directly I2S data from CD PRO, do I need any reclocking in transport to avoid jitter? Would it be redundant?

Andrea
Hi Andrea,
1. For sure, you can take I2S signals from CD Pro and you don't need any re-clocking before feeding into FIFO. It is 'redundant' . Because FIFO will isolate all the input jitter.
2. Interfacing I2S with PCM63, you have to use a little converter board. PCM63 do not directly support i2S.
3. From 5842 doc, I found it do not support i2S input. It's kind of 'SONY' format. In this case, maybe you need a special version of FIFO to output that format.
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Old 16th April 2012, 02:27 AM   #367
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Originally Posted by iancanada View Post
Hi Andrea,

3. From 5842 doc, I found it do not support i2S input. It's kind of 'SONY' format. In this case, maybe you need a special version of FIFO to output that format.
I think the 5842 outputs a sony version but inputs I2s. I say this because I built a DAC with CS8412 to 5842 with the cs8412 configured with M0,M2,M3 grounded and M1+5V which is the I2s output mode of the CS8412 ?
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Old 16th April 2012, 04:19 AM   #368
kazap is offline kazap  Australia
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Originally Posted by iancanada View Post
..... with 128Fs MCLK, theoretically it could go up to 768Khz, but I don't have anything to test so far. Do you know which USB could go up to 768Khz?....
That's an impressive indication of potential high performance for your FIFO. Thanks!

Quote:
Originally Posted by iancanada View Post
..... Do you know which USB could go up to 768Khz?....
I believe the Phasure is the trail blazer in this area:
Phasure NOS1 24/768 async USB DAC
with 24/768 async USB DAC interface to PCM1704 and a special software filter to reduce artefacts its a brilliant design.
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Old 16th April 2012, 10:05 AM   #369
qusp is offline qusp  Australia
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the sabre will double that in OSF bypass mode if you can feed it to it
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Old 16th April 2012, 03:59 PM   #370
zinsula is offline zinsula  Switzerland
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I think your timing diagram for the AD DAC's look good, Ian.

If I might suggest one more thing:
Would it be possible to create a second DATA line per channel, which has the bits inverted?
Would be cool...easening a balanced DAC design. PCM1704 adopters don't need it though....
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