[sdiy] ARM based digital synth.

[Alwyn Lloyd]

On Wed, 13 Sep 2006, Eric Brombaugh wrote:

> > What i have found out though is the phillips chip have 2 SPI ports, and
> > can be run at a maximum of 1/8th of the clock rate.  which is fast.  I'm going
> > to have a look at whether i2s and spi are close enough that one could use
> > the spi ports as i2s ports.
>
> Interesting idea. There was an article in the latest issue of Circuit
> Cellar that described an I2S port implemented on a TI DSP using a SPI
> port and some of the internal timers. You might be able to lash up
> something like that - sort of half software & half hardware.

Ooh, that sounds right on the money.  Do you have the issue number its in?
Magazines like that arive a bit later over here in AU.


> Interesting. The main problem is that I2C is somewhat slow. Did I see
> that Philips part has CAN bus on it too? How does that compare in speed
> to I2C? There's a guy around somewhere who's doing a synth system using
> CAN bus for all inter-module communication...

It does have a CAN bus, which runs at 1Mbps.  I'm not to sure what speed
normal i2c runs at, but fast i2c supports up to 400Kbps.

However, speed isn't a huge factor for this application.. (GUI and patch
storage).  Midi provides reasonably good responsiveness and thats only
31mumble Kbps, so as long as its faster than that it shouldn't be too much
of a problem for a GUI use.

The CAN bus synth stuff is at:
http://wiki.netsynth.org/index.php?title=Main_Page


Cheers,
[zar]