Fw: [sdiy] Spartan 3 eval... FPGAs for s-diy?

[ASSI]

On Monday 15 March 2004 21:05, Jaroslaw Ziembicki wrote:
> is there anyone who built anything for sound generating/processing
> based on an FPGA?

Back at the university I was in a group doing research on 
reconfigurable computing. For audio applications we've had an LPC Codec 
and several FFT kernels on a dynamically reconfigurable CPU built on an 
XC6200 (R.I.P.) to compare with implementations of the same on 
commercial DSP and general purpose CPU. The CPU core in the FPGA was a 
very modest RISC (to save gates) plus a reconfigurable computation unit 
that would execute customized instructions tailored to each algorithm.

> I've been playing with Altera MAX PLUS II for 2-3 weeks now and I can
> see that the possibilities are enormous. Even with FLEX10K family
> members with 10,000 to 50,000 gates it's possible to create a pretty
> signal processor
> (example: 16x16 multiplier, 32 bit adder, 256x16 RAM, 1024x32 ROM -
>  - and it all fits into a half of an EP1K50).

The key to getting good DSP performance from an FPGA is to max out all 
resources. In a DSP you typically waste a considerable number of cycles 
waiting for pipeline hazards to clear or data from memory to come in. 
Then there are always some functional units that are mostly unused. 
Only if you don't do the same thing in an FPGA you get better 
performance, but this is quite hard to achieve. Minimizing the clock 
cycle time also often requires to switch to serial arithmetic and/or 
redundant number systems, but this is getting easier with the advent of 
dedicated multiplier resources in FPGA. FPGA based systems used to be 
good on doing things in parallel, but there's now a number of DSP based 
on SIMD and MIMD principles that squeeze out that particular advantage.

> Any experiences? Reverb simulation? Polyphonic synths? Real time FFT?

I'm still researching the options as far as eval boards go. Also, for 
the latest slew of design software it looks like I need a new computer 
as well... My plan is to get a modernized version of the WAVE ASIC plus 
perhaps some LFO and envelope generators into an FPGA.


Achim.
-- 
+<[Q+ * Matrix-12 * WAVE#46 * microQkb/Omega * XTk/30 * sonic heaven]>+

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