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Old 15th May 2013, 02:41 PM   #1
joro_s is offline joro_s  Bulgaria
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Location: Sofia
Default XMOS DSD 384 kHz / 32bit USB

Hi Everyone,

For quite some time now Iíve 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) Ė 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
Attached Images
File Type: jpg i2soverusb.jpg (678.7 KB, 6947 views)
File Type: jpg pcm5102 spectrum.jpg (428.3 KB, 6405 views)
Attached Files
File Type: pdf RMAA_XMOS.pdf (99.9 KB, 794 views)
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Old 18th May 2013, 12:27 PM   #2
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It is two channel or multi-channel ?
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Old 20th May 2013, 05:26 PM   #3
joro_s is offline joro_s  Bulgaria
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I'm using single-core XMOS processor, for multi-channel audio one has to use dual-core XMOS processor. I plan to design such PCB, but it won't be 77E, such as this two-channel audio PCB.
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Old 21st May 2013, 03:56 AM   #4
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Availability? Price?
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Old 21st May 2013, 04:44 AM   #5
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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
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Old 22nd May 2013, 08:11 AM   #6
joro_s is offline joro_s  Bulgaria
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Hi,

Quote:
Originally Posted by lil' knight View Post
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.

Quote:
Originally Posted by luxury54 View Post
...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
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Old 22nd May 2013, 09:26 AM   #7
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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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Last edited by luxury54; 22nd May 2013 at 09:44 AM.
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Old 24th May 2013, 03:44 PM   #8
joro_s is offline joro_s  Bulgaria
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Hi,

I update my profile.
Quote:
Originally Posted by luxury54 View Post
... 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?
This 16 pin IC is 74HC138 (which is located on PCM5102 pcb) and it is only for indicating recieving Fs.

Regards,
Joro
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Old 25th May 2013, 12:35 PM   #9
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Quote:
Originally Posted by joro_s View Post
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?
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Old 25th May 2013, 02:28 PM   #10
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Waiting for GB.
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