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

[Alex Norman]

> > Digikey sells Cypress Semiconductor 256Kbit(32K bytes) 45ns SRAM chips in
> > dip form for $7.50
> > http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=STK14C88-3W

Not stocked :(

-Alex

On  0, Alex Norman <alex at x37v.info> wrote:
> On  0, Greg Grunest <greg at grunest.com> wrote:
> > IMHO, DRAM is a real pain to deal with.  Unless you want to deal with
> > implementing your own DRAM controller or you really *need* the speed /
> > density / price that DRAM can offer I tend to avoid it.  The refresh
> > circuitry and RAS / CAS timing will drive a sane man to drink.  You also
> > have to deal with issues like pipelining, precharge, CAS latency and
> > bursting.  SRAM on the other hand is much easier.  You put an address on the
> > address pins and then either read or write data on the data pins.  That's
> > it.  It always just kind of works whereas I've spent a ton of time debugging
> > DRAM timing and commands in the past.
> 
> Thanks for the advice!
> 
> > 
> > You should be able to implement a 64KB SRAM chip with just two latches using
> > 11 or 12 pins on an Arduino and it's really straight forward. Adding
> > additional 64K SRAM chips (128K, 192K, 256K etc...) is as easy as peeling
> > off another pin from the Arduino and tying it to the chip select of the
> > additional SRAM chip (or you could mux it).
> 
> Sounds like a plan.  I'm assuming you'd tie the data I/O directly to the
> micro-controller, drive the address pins with shift registers, and drive the
> ~CE, ~WE, ~OE directly?
> 
> I guess the ~CE could be used as an address bit.. so these could be driven by
> the shift regs.
> 
> The nonvolatile store feature is pretty neat.
> 
> > 
> > Also, you should be able to easily outperform your data write requirements
> > for storing audio with any available SRAM chip and an Arduino using this
> > approach. 
> > 
> > Will the Arduino DAC conversion rate and the bit depth deal well with sound?
> > Especially if you're looking for a 44.1khz sampling rate (CD quality).  I
> > tried to do the math on this but my brain stopped working about an hour
> > ago.(All I can do now is blabber and type.)
> 
> I have 8-bit 44.1Khz output with a teensy++ working well right now, though who
> knows what will happen once I add input..
> I'm currently storing my audio in program memory..
> 
> -Alex
> 
> > 
> > Regarding SRAM being too expensive, I'd agree compared to the density (cost
> > per cell) for DRAM but unless you're building 1000  or more of something,
> > I'd argue that you'll spend more money, time and effort getting a DRAM
> > solution to work.  Especially for building 1-off solutions.
> > 
> > Digikey sells Cypress Semiconductor 256Kbit(32K bytes) 45ns SRAM chips in
> > dip form for $7.50
> > http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=STK14C88-3W
> > F45-ND
> > If you don't need the dip packaging, they get much cheaper with higher
> > densities.  1Mbit(128K bytes) 45ns for $2.50
> > http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=428-2066-ND
> > 
> > Granted, in comparison DRAM chips are 4M at 35ns for $1.60 and 16M for $3.50
> > (but they suck!!!)
> > 
> > -greg
> > 
> > -----Original Message-----
> > From: dorkbotpdx-blabber-bounces at dorkbot.org
> > [mailto:dorkbotpdx-blabber-bounces at dorkbot.org] On Behalf Of Jason Plumb
> > Sent: Thursday, July 23, 2009 10:44 PM
> > To: A discussion list for dorkbot-pdx (portland, or)
> > Subject: Re: [dorkbotpdx-blabber] Microcontroller + RAM.. recording/playback
> > 
> > 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
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