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Old 5th January 2012, 03:30 PM   #21
sgpu is offline sgpu  United Kingdom
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Thanks for the input Marce. I think you could be a great resource and not too far from me either. ;-)

I'm fairly bored right now and like to spend too much time drawing ideas with Lucid Chart. If I were to go with the ATX form factor I'm guessing we would end up with something like below and use a connector like the Samtec Searay and standardize the bus. ATX would limit the size of connector on the back plates - just big enough for mini-xlr though.

Click the image to open in full size.

Last edited by sgpu; 5th January 2012 at 03:40 PM.
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Old 5th January 2012, 05:03 PM   #22
marce is offline marce  United Kingdom
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That looks nice, DDR3 ram an all, heaven.
I've spent the last 25 years designing PCB's and the enclosures to house the electronics, and still find it a fun and interesting job. in my early days I did a lot of Bus based systems based around VME and G64 (For a company called Syntel) such as this, which we did for Daresbury (Topaz later evolved into somthing bigger):
http://accelconf.web.cern.ch/accelco...C1994_1551.PDF
The fun of doing something like this is you have complete freedom of size etc etc, in this case it could be made quite compact depending on the size of the daughterboards, the main processing and memory section would fit in a 100mm x 100mm area of PCB, with BGA based designs (1.0 and 0.8mm pitch) you can easily (!!) get 4000 pins in that sort of area with double sided placement.
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Old 5th January 2012, 10:59 PM   #23
sgpu is offline sgpu  United Kingdom
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Been tinkering and scheming.

1). Boot from SD as per BeagleBoard-XM
2). 1Ghz Cortex A8 and 750Mhz C674 DSP
3). HDMI 1.3a with upto 8ch PCM audio.
4). USB-OTG port
5). Gigabit LAN
6). Audiophile grade clocks for system and A/V subsystems.
7). Narrow depth ATX based form factor
8). PCIe x1
9). 6 multifunction A/V expansion bays (such as amps, crossovers, inputs, outputs).
10). 12V input - power consumption no more than 8W with no expansion cards.
11). Sametec Searay connectors for expansion boards.

Something along the lines of...

http://www.lucidchart.com/publicSegm...b665/image.png

Last edited by sgpu; 5th January 2012 at 11:02 PM.
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Old 5th January 2012, 11:34 PM   #24
sgpu is offline sgpu  United Kingdom
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Moving i2s around those distances could prove problematic. Is 150-180mm too far to travel?
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Old 6th January 2012, 10:29 AM   #25
marce is offline marce  United Kingdom
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I'd have to look at the spec, we use i2c, used it on a board 100x200, from memory this was probably over 180mm daisy chaned to 7 Codecs.
Audiophile clocks wouldn't communication grade be better
That layout looks ok, can you create basic 2D dxf of the boards, I only have DraftSight at home (a free Dassault 2D drawing package, if you use other Dassault products such as SW).

Last edited by marce; 6th January 2012 at 10:32 AM.
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Old 6th January 2012, 10:49 AM   #26
sgpu is offline sgpu  United Kingdom
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;-) Indeed! Crystek? CCHD-957. Bit pricey though.

Last edited by sgpu; 6th January 2012 at 11:08 AM.
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Old 6th January 2012, 01:05 PM   #27
sgpu is offline sgpu  United Kingdom
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With reference to the DM8148 DSP I have been doing some more reading regarding clock generation and management. I'm working my round the A/V subsystems to see what is the best clocking setup.

We could isolate the McASP clocks with an external oscillator directly connected to AUXOSC_X1 pad. This is a bypass of the internal DPLL LJ and can feed each McASP(n) ahclk directly. I think this would be the cleanest solution and will synchronize all McASP units to a clean reference. This same clock can also supply the i2s clock for the HDMI audio transmitter.

Quite a few registers to set...
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Old 6th January 2012, 02:41 PM   #28
marce is offline marce  United Kingdom
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Sent a PM regarding this question, as I said in it I do not have the experience to answer this question, anyone else.
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Old 6th January 2012, 04:00 PM   #29
sgpu is offline sgpu  United Kingdom
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Thanks Marce. Any help is appreciated. If there are any TI specialists on here, would this be possible with the DM8148? This would give developers plenty of scope for A/V projects as they have the choice of where they source the clock.


Click the image to open in full size.

Last edited by sgpu; 6th January 2012 at 04:17 PM.
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Old 7th January 2012, 03:50 PM   #30
sgpu is offline sgpu  United Kingdom
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Perhaps a BeagleBoard like device aimed at A/V professionals might be popular. This would enable possible glueless connection to a whole host of DIY and commercial projects. Any ALSA specialists here?

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