[sdiy] Bus for digital patching of synths

[cheater00 .]

On 18 Nov 2013 06:10, <nvawter at media.mit.edu> wrote:
>
> Ah, yes, a clever idea to exploit PCIe.
>
> I bet for many FPGAs there is readily available code for PCIe transacations...

My worry is what the minimal delay from ADC to DAC would be if this is
in use. Unlike in recording, here we want the latency to be very
small, otherwise the instrument will simply not be able to work
correctly. The issue is not only that the sound must come out when you
press a key.. but also that the various envelopes and other stuff
that's triggered must line up in time. And this is a system which
accepts digital and analog inputs at any point. Perhaps going for just
digital might ease this up a bit, but perhaps not.

> and it could be developed inside a standard PC until its ready for takeoff.

Yes, that is great too. I hadn't actually thought what a facilitation
this is until you mentioned.

> so, over at opencores, there are a number of them under the category "Prototype Board."
> In particular, there is one called Audio DSP PCI Card.
> http://opencores.org/project,fac2222m

I'd never heard of opencores, I'll browse around, thanks.

> I think backplanes are not terribly expensive, except for a few things, they're normal circuit boards.  They'll probably have many layers.  They sometimes have heavier copper, although I don't know if that's a marketing gimmick or seriously necessary.  Also, backplanes tend to be long, wide things, so in terms of surface area they can be large.  But it may be worth it since it's a long, long term investment.

Recently Asus launched a board specifically for bitcoin mining which
has a lot od x1 slots and even comes with those flex extenders. If
this is a start of a trend it could be better to use motherboards and
find a way to chain them, rather than use expensive irreplacable
backplanes.

http://www.pcgamer.com/2013/11/15/asrock-releases-motherboards-designed-to-mine-bitcoins-generate-internet-moolah/

But again, the question is how much latency this adds.

> It might be possible to start with old PC motherboards and "light them" with your own PC signals!??!  who knows ?

I don't unserstand what you mean by "light them". Can you explain?