[dorkbotpdx-blabber] Microcontroller + RAM.. recording/playback

[Jason Plumb]

Alex Norman wrote:
> I'm looking to build a very simple audio/control voltage recorder/"sampler" with
> a micro-controller.  I realize a DSP might be the best thing for this but I'm
> curious if I can do it with a micro-controller for cheap.

So this has been a desire of mine for a while now too.  I'd love to be 
able to do a few seconds at 44.1kHz mono (ideally up to like 60 or 120 
seconds!!).  I think that DSP is probably overkill for this application 
tho....there's very little *processing* involved, most of the work is on 
the bus.

> Basically, the piece that is the major problem is finding a reasonably large 
 > memory device which I can quickly read and write single bytes at a
 > time.

This really is the core issue...finding a sweet spot for complexity 
versus price versus capacity.  DRAM is so damn cheap now that it seems 
the way to go...but none of the popular MCUs interface with any out of 
the box.  You'd end up using a controller or rolling your own, the 
price/complexity of either is kinda cost prohibitive (I suspect).

In my experience, it's hard to find static RAM or serial RAM that are 
big, fast, and cheap enough for this application.

> I've been thinking that I could actually do this with eeprom if I make it so
> that the device doesn't 'record' and 'playback' at the same time.. but it would
> be ideal if I could do both..

Would eeprom really be fast enough?

What's in the guts of the Line 6 or Echoplex devices?

Paul: Don't pretend like PJRC hasn't interfaced with DRAM before.  :) 
What are your thoughts on doing this?  I fear when it comes to DRAM 
there are a bazillion variables...

-jason
http://noisybox.net