[sdiy] Spin Semiconductor FV-1, anyone?

[Eric Brombaugh]

Tom Wiltshire wrote:
> 
> On 28 Oct 2008, at 20:07, Eric Brombaugh wrote:
>> On a related note - one thing I remember seeing sometime in the past 
>> was a teardown on the Alesis Micron low-cost analog modeling synth. If 
>> I recall correctly, it was basically a gang of 8 AL3201 chips with a 
>> separate controller to manage them all. If the FV-1 could be employed 
>> in a similar way you could do some pretty nifty stuff with it...
> 
> Cunning! I like it!
> If you did it that way with the Spin FV1, you'd even get 3 CV inputs (or 
> knobs) per section. That could make quite an interesting piece of hardware.
> 
> However, AL3201 uses codec interfaces to talk to ADC/DAC, so you've got 
> digital audio in and out from the chip. FV1 only has analog in/out as 
> far as I can tell. Makes it simpler for what it is designed for, but if 
> you wanted to put a lot of them in a long chain, your poor signal would 
> get converted from digital to analogue and then back again a *lot* of 
> times before you were done...

Here's a link to the pictures:

http://matrixsynth.blogspot.com/search?q=pictures+inside+my+Alesis+Micron

The Micron consists of a Freescale Coldfire processor, an Altera gate 
array, nine Wavefront AL3101 DSPs, an AL3201 and various support 
circuits. Not quite what I had described.

More details on the Wavefront parts here:

http://www.wavefrontsemi.com/products/AL3101pop.html

http://www.wavefrontsemi.com/products/AL3201pop.html

Seems like the '3101 has a more general-purpose architecture than the 
'3201, but also lacks the large DRAM used for buffering delays. It also 
executes a lot more instructions per wordclock (1024 vs 128) so can run 
much more complex algorithms.

Interesting parts, but due to the requirement for external ADC/DAC and 
the need to load code via SPI they're not as DIY-friendly. The FV-1 OTOH 
seems like a pretty good bet for home-made effects, especially if you're 
interested in low-level coding on an very unique architecture.

I'll probably stick with dsPICs though. Cheaper, about the same MIPS, 
more I/O and a decent development environment (including C compiler).

Eric