XMOS DSD 384 kHz / 32bit USB

joro_s

Member
2009-09-07 2:12 pm
Sofia
Hi Everyone,

For quite some time now I’ve been working on asynchronous USB audio signals. I would like to introduce you the final version. The XMOS firmware is changed so it can play 32-bits PCM audio and to play DSD audio.

Features:

1. XMOS 500MIPS 64-pin chip for transmission of asynchronous USB audio data to I2S line.
2. Sampling frequencies: 44.1kHz, 48kHz, 88.2kHz, 96kHz, 176.4kHz, 192kHz, 352.8kHz, 384kHz
3. Resolution: 16-, 24- and 32-bits.
4. I2S or right-justified data (external pin configuration) in 32-bit frame.
5. Two low jitter oscillators for audio 45.158MHz and 49.152MHz.
6. Input for external master clock.
7. LP5900 ultra low noise linear power regulator (6.5 uV RMS).
8. No switch mode power supplies in the PCB board.
9. Galvanic isolation (outputs, two oscillators and reclock are after the isolator).
10. Galvanic isolated output with open collector for DAC configuration in DSD mode.
11. Automatic detection of data type (PCM or DSD).
12. Master clock outputs: 45.1584/49.1520MHz and 22.5792/24.5760MHz (I2S 22.5792/24.5760MHz are reclocked by edge from 45.1584/49.1520MHz)
13. Three different ways to power the board, possible configurations:
13.1 Power by USB bus.
13.2 The USB part is powered by USB bus, but the generators and the reclock are fed by a separate external power supply.
13.3 Both the USB part and the generators with the reclock are fed by two different external power supplies. (The selection of a configuration is done by jumpers)

DSD Audio over PCM frames
DSD64(2.822400MHz) and DSD128(5.644800MHz) by method DoP with 0x05/0xFA markers.
In DSD mode outputs are DATA Ldsd -> DATAi2s, DATARdsd -> LRCKi2s, BitClockDSD -> BitClockI2S.
SPDIF output (through DA101C transformer) – 44.1kHz, 48kHz, 88.2kHz, 96kHz, 176.4kHz, 192kHz (16-24 bits).

Additionally, I developed a DAC PCM5102 PCB to the XMOS PCB for monitoring purposes.
This PCB is made for indicating sampling frequencies. DAC PCM5102 accepts 16-, 24-, and 32-bit audio PCM data, but it can not play DSD signal.

Kind regards
 

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luxury54

Member
2008-12-12 7:16 am
very nice and neat design, I like especially how small and compact it is together with the PCM5102 DAC board;
do you plan a group buy for these? I would be very interested at least in the PCM5102 board.
how have you configured the PCM's digital interpolation filter, is it FIR normal or IIR low latency ? thanks
 

joro_s

Member
2009-09-07 2:12 pm
Sofia
Hi,

Availability? Price?
I expect PCBs on monday (27.05). XMOS board costs 77 Euro. Both XMOS and PCM5102 boards cost 99.9 Euro. These prices are without shipping. Shipping costs depends on destination so it's not a fix price.

...do you plan a group buy for these?......how have you configured the PCM's digital interpolation filter, is it FIR normal or IIR low latency ? thanks
Group order - there will be discount
The default state is FIR filter, but there is an input port for configuration so one can choose between FIR / IIR filters.

regards,
Joro
 

luxury54

Member
2008-12-12 7:16 am
thanks for the updates on the prices,
maybe you could organize a group-buy in the "vendor's bazaar" part of the forum where everyone interested could sign up;
what are the quantity limits for each board so that they could benefit a price drop and how much would be that price?
where are you located if I may ask, EU or USA? (it's for an estimative calculation of shipping charges for my location)

edit - what is that little board in the upper right corner of your pictures ?
- is the reclocker/isolator part already mounted on the USB-I2S main pcb or it has to do something with that little board?
hehe, now I realize that is the other side of the PCM5102 pcb :) , so I was wondering what is the use of that 16 pin IC? is it only for the sample-rate indicator or some kind of I2S buffer? because I saw also "I2S OUT" pin headers present on the board

best regards
 
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linuxfan

Member
2007-12-09 3:09 pm
7. LP5900 ultra low noise linear power regulator (6.5 uV RMS).
...
13.3 Both the USB part and the generators with the reclock are fed by two different external power supplies.
i) Does this mean that both power inputs (USB and generators/reclock) have LP5900 regulators?

ii) what external power supply do you recommend for each of these power inputs? Just a basic 3pin pre-regulator, or is something high-end called for?
 
i) Does this mean that both power inputs (USB and generators/reclock) have LP5900 regulators?

In the chosen topology, precisious power regulator is needed only for generators/reclock. LP5900 is only for the generators/reclock.


ii) what external power supply do you recommend for each of these power inputs? Just a basic 3pin pre-regulator, or is something high-end called for?

The USB part includes everything related to the processing and asyncronous transfer (XMOS), this part is of one side of the galvanic barrier, it can be powered by 3 pin regulator. On the other side of the galvanic barrier are generators and reclock, they need a "clean" power and 3pin pre-regulator is not recommended. It can be used LM317 regulator in circuit "Improved Ripple Rejection". In this mode Ripple Rejection Ratio is improved by 10dB.

Regards,
Joro
 
Is this a commercial thread of a thread on the development of a DIY project? Since the thread is created in the general area of the forum, I assume you'd like some feedback on the design?

Honestly the layout looks like a slight variation (with some of the variations being a step backward, presumably to make the PCB cheaper) on what Lorien has provided previously as a sneak preview of the future WaveIO revision. I personally wouldn't purchase from a vendor where the R&D was simply to recreate a PCB layout from a screenshot of another forum contributor.

The complete component layout and partitioning of the isolated portions of the circuit are really very very similar.
 
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Forane12

Member
2008-04-26 8:25 pm
Is this a commercial thread of a thread on the development of a DIY project? Since the thread is created in the general area of the forum, I assume you'd like some feedback on the design?....
....The complete component layout and partitioning of the isolated portions of the circuit are really very very similar.

I must say that I have seen working prototypes of this device long before Lorien posted his update, this is not what you are afraid of and the guy behind it is way too smart to just copy something, you know it is not that simple. Smart enough to write his own firmware. Some people that have it are selling their Exa devices, I plan to try it too someday. No affiliation with the seller apart from being in the same country.
 
lorien posted that design for the first time many months ago, but sure lets give the benefit of the doubt, which still means this thread has no place being here since its not for getting feedback on a personal project, rather just an attempt at free advertising for a commercial product.

makes sense selling the EXA after having one, EXA lacks features this and Loriens design have and is too expensive to have just sitting around.

it looks pretty average to me, but hey, price is OK. amanero plus acko ISO/reclocker seems a better choice for the same money though IMO.
 
Is this a commercial thread of a thread on the development of a DIY project? Since the thread is created in the general area of the forum, I assume you'd like some feedback on the design?

Yes. This started as a DIY project a long time ago and this is phase 4 of this project (preferences from Bulgarian audio fans are taken into consideration). This thread was not published in this forum, because my English is not so good.

Yes, I would like some feedback.
Honestly the layout looks like a slight variation (with some of the variations being a step backward, presumably to make the PCB cheaper) on what Lorien has provided previously as a sneak preview of the future WaveIO revision
At the end of my post I'll give a link to bulgarian DIY forum, although I don't want to do this but I felt aggrieved (if the moderators take to account they can delete it). One can see the dates of first thread (6 january 2013). Phase 3 is realized in 2012, but the thread is published later, because I was testing FW. Phase 4 (this board) was published on 17 march 2013. So one can see how close are designs of phase 3 and 4. I'm an telecomunication engeneer, audio is my hobby and that's why this project is developing so slowly (in my spare time).

If this thread is in wrong place, then moderators can move the thread.

About the site, it was crearted a few days ago, by request of my son (he made the site and still working on it).

link: ?????????? ?????? XMOS USB-I2S - ????????

Regards,
Joro