[sdiy] ARM based digital synth.

[Alwyn Lloyd]

On Tue, 12 Sep 2006, Eric Brombaugh wrote:

> Looks like a nice development system! Lots of useful I/O, fast and
> definitely inexpensive. You can get cheap/free compilers for ARM7 too.

yes, free compilers are always nice.. though how optimised things like gcc
are for ARM im not sure.

>
> Nice drawing.

thanks. Its done in OmniGraffle.  Its really nice for doing quick "table
napkin" sketches :)


>
> There are a lot of decent quality and inexpensive AC97 codecs available.
> The big problem you'll run into is that you really can't bit-bang the
> AC97 interface in software - you'll need some sort of customized
> hardware to talk to it. Might I suggest an FPGA or CPLD?

I was hoping to keep it fairly simple and cheap, and im not sure i'd be
quite up to designing something like that, though atmel have an apps note
on a very similar thing as part of their arm notes.

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.

>
> It sounds like a neat project - I'd like to see what you come up with.

The aim is to try and make something thats fairly straightforward and
simple to make.  The other thing is versitility.  All you need to do is
make a new UI panel and connect it to the i2c bus, write some new software
and you can have a different synth..

Cheers,
[zar]