[LAD] FOSS Ethernet Soundcard

Karl Hammar karl at aspodata.se
Tue Dec 1 18:31:24 UTC 2009


Patrick Shirkey:
> Just to recap. These are the points that have been discussed so far.
> -------------------
> Physical Size
> -------------------
> 
> http://www.rittal.com/products/ArtikelDatenblatt.asp?ArtNr=1360500&lang=GB
> 
> 600 mm x 600 mm x 350 mm

No, this is where I will put my system into. The actual "computer" 
would be much smaller. I'm planning on something like

 h: ~240, w: <200, d: < 200mm

But I don't think you should have to abide to that.

+++++

For the "soundcard" part, it might be more useful if we instead talk 
about interfaces.

With SPI, we are free to "attach" many different cpu-cards, it's just 
clock, data out, data in, and a few chip select lines. And we can 
potentially get 10-20 channels at cd quality.

With faster i/o, we can use the cpu's memory interface, or
some ordinary bus like pci or pci-x.

I'm not for pci or pci-x at this point, since that would be for me a 
totally different project. Unless, of cause, someone else takes care 
about the "bus" part, and I and others do the ad/da and analog part.

With spi or the memory bus, we cannot use an ordinary pc --- to bad.
But we could use the atmel network card mentioned a few lines below,
or the card I will eventually build, or some card someone else provides
source to.

> ---------------
> Hardware
> ---------------
> No decision has been made on the viability of designing a board from 
> scratch.

I will probably do everything from scratch, but given good and
sensible interfaces card<->card, one could possible use "any"
suitable cpucard.

> - You have access to this board for development/testing:
> http://www.atmel.com/dyn/products/tools_card.asp?tool_id=4102

Ack.

> The aim is to provide upto 8 audio i/o ports.

I don't think we should set an upper limit, instead it would be 
interesting to see how many channels the system could support.

I would say we try to make (input and output)

 one desent channel, e.g. 16bits, 44.1/48kHz
 one very good channel (if we manage), 24bits 192kHz, to try the limits

And then see how many we can fit into the system.

And, would that be an line input, or mic input channel, or
(software) switchable?

Talking about, i/o. Would buttons, leds, relays, linear and rotary
things (what is their name?), etc. be useful ?

> Connectivity via Gigabit ethernet.

I don't think the atmel can do gigabit. Fast ethernet (100Mpbs),
is a more realistic choise unless we switch cpu.

> --------------------------
> Firmware/Software
> --------------------------
> The device will run Linux OS.
> Audio data transfer will be via netjack using CELT compression.

Ack.

> -------------
> Website
> -------------
> Need to define project vision, setup wiki, git-hub etc...

Ack.

I have some readme's at [2], and I will put all my other design files 
there.

Here are some thoughts (extract from [3]):

 The requirements are
 . it should run linux
 . developed with open source tools, current choise is gEDA
 . expandable, you be able to easily add e.g. 8 D/A ports, 32 DIO etc.
   preferably hotpluggable
 . electrically rugged and EMC safe
 . easy to make and build yoursalf, preferable double layer card
 . the components should be available/purchable for a normal hardware hacker
 . the should not cost to "much"
 . no card edge connector

 It seems that my "archetectural" choises are
 . a single board computer
 . a stackable system like pc104, pico-itxe or arduino
 . a card frame system, either
  - whith a backplane bus, like VME or CompactPCI
  - or with the "backplane" on the cpu card, the motherboard style like ATX

 The one which is easiest to expand is the card frame system with a backpland,
 I will make my first try with that.

> - I have a couple of pico-itx boards which are similar to the Atmel 
> boards but a little more powerful
> http://www.via.com.tw/en/initiatives/spearhead/pico-itx/

They don't have a spi master on board we could use for slow i/o,
nor can we easily attach things to the memory bus for fast i/o.
So for the industrial control thing theese are not that easy to use.
(I have checked all the itx cards, and all except one states that the
spi is for testing (I assume jtag) purposes only).

If we go the mini/micro/nano/pico-itx route, I think we need to make an 
pci/pci-x card. That would be nice, but I don't think I'm up to that
yet, are you?

There is also a pico-itx -e version that has a so-called sumit [1]
connector.

> Both platforms run Linux natively so that will allow us to get something 
> running fairly quickly for testing purposes.

I don't see any pricipal difference between X-itx card and an ordinary 
pc. If we say we want it to run on a X-itx card, that would be the same 
as saying it should run on an ordinary pc. And that would imply 
pci-x I guess.

> If the above details are correct it looks like the next step is to 
> define the best way to connect external audio i/o to the device.

Regards,
/Karl

[1] www.via.com.tw/en/downloads/datasheets/initiatives/FAQ081029Pico-ITXe-P710.pdf
[2] git://aspodata.se/openhw.git
[3] http://aspodata.se/openhw/README
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Karl Hammar                    Aspö Data               karl at aspodata.se
Lilla Aspö 148                                                 Networks
S-742 94 Östhammar          +46  173 140 57                   Computers
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