[Fpga-synth] Try out spartan3e projects, questions

[malik martin]

wow! had no idea a virtex could cost so much!!!

On Wed, Aug 13, 2008 at 10:24 PM, Eric Brombaugh <ebrombaugh1 at cox.net>wrote:

> Dave Manley wrote:
>
>>
>> I'll chime in with one comment: the max FPGA frequency is no where near
>> the max frequency of modern processors.  I haven't looked at DSPs in a long
>> time, but assume some must be able to run in the GHz range, while most FPGAs
>> are going to be limited to a few hundred MHz at most (with any significant
>> amount of logic).  In terms of clock speed only, what is the fastest DSP out
>> there?  I see some AD Blackfin rated at 750MHz.
>>
>
> True, but it depends on what type of FPGA and DSP your talking about. A
> Spartan 3E probably tops out around 250MHz if you're lucky, but that's a $15
> FPGA. I'm using some high-end Virtex5 parts that can run > 500MHz internally
> and have 640 MAC units. Lets see - that works out 320GOPS max. Name me a DSP
> that can get anywhere close to that? Of course, that's cheating a bit - that
> part costs $2500. :)
>
> The big advantage of FPGAs is parallelism - even on a low-end part you can
> clock all those registers, multipliers and RAMS simultaneously. Even
> high-end DSPs with multiple execution units (normally no more than 8 or so)
> have bus bottlenecks that will prevent you from keeping those resources busy
> all the time.
>
> The big advantage of DSPs is flexibility - it takes only fractions of a
> second to reconfigure a DSP for a completely different task (ie, load a
> program), or to compile & debug code. The FPGA configuration process is
> slower and the compile times can take hours.
>
> There's a lot of overlap though and you can use both technologies to
> accomplish many of the same things. If your only tool is a hammer...
>
> Eric
>
>
>
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