DSP vs Firmware

On Fri, 30 Jul 2004 13:17:06 -0700, "Jon Harris"
<goldentully@hotmail.com> wrote:

>"Tim Wescott" <tim@wescottnospamdesign.com> wrote in message
>news:10gkscd310g4q40@corp.supernews.com...
>> Peter Choi wrote:

[snip DSP-FPGA comparison]

My last product had a large FPGA to do some heavy grunt high speed
datapath work.  It also does some light-weight DSP work ... with a
small risc microprocessor implemented inside the same FPGA.

:)

Regards,
Allan.

Fred Marshall wrote:

> "Jon Harris" <goldentully@hotmail.com> wrote in message
> news:2mvo7uFrdqosU1@uni-berlin.de...
> 
>>"Tim Wescott" <tim@wescottnospamdesign.com> wrote in message
>>news:10gkscd310g4q40@corp.supernews.com...
>>
>>The places where FPGAs do seem to get used for DSP are in very high sample
> 
> rate
> 
>>applications, where traditional DSPs just aren't fast enough (e.g. RF).
> 
> In this
> 
>>case, the data width is usually quite small as well, which decreases the
>>required FPGA logic, and the algorithms are often simple, like a static
> 
> FIR
> 
>>filter.
> 
> 
> Also in video processing ..... where the two approaches tend to compete a
> bit more. If there are complex algorithms involved then a high-powered DSP
> might be indicated.  Otherwise, a lot of video can nicely be done in an
> FPGA.
> 
> Come to think of it, I don't hear much about the TMS320C6000 series here in
> comp.dsp.  Any experience here?
> 
> 66MHz FPGA designs do well in video applications and have likely gone up in
> speed in the last 5 years since we were doing those designs.
> 
> I'm not familiar with the applications of FPGAs in cell phones .... but I'm
> pretty sure that the big FPGAs wouldn't fit!
> 
> Fred
> 
> 

Speeds have gone up.  FPGA's do very nicely in custom imager 
applications where you need DSP-lite and lots of shoving data around -- 
the application that I'm thinking of has two separate SDRAM banks to 
achieve the necessary speed; you may be able to do this with pairs of 
DSP chips, but it'd be slightly ridiculous.

-- 

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

"Peter Choi" <choi@mecca.ca> wrote in message
news:6UsOc.137453$Mr4.108053@pd7tw1no...
> Hello,
>
> Oh I didn't know FPGA uses more power than a DSP.  I thought FPGA would
use
> less since you build only the necessary logic for it.

Most of the current fpga's are sram.
Newer generations use less power.

Have a read of the datasheets for fpgas and dsp chips
for min and max power use.

Also fpga's can't unlike some dsp's / mcu's
turn parts of themselves off or hibernate  etc
if you require very low power use.


This may be of interest, it does come from a dsp vendor though.
http://focus.ti.com/lit/an/spra879/spra879.pdf

or
http://64.233.161.104/search?q=cache:PrqtozvFQAQJ:focus.ti.com/lit/an/spra879/spra879.pdf+choosing+DSP+FPGA+ASIC&hl=en

http://www.eetuk.com/bus/news/OEG20040426S0012

Other things

can get some pretty high speed dsps - 1GHz

unless your design is highly parallel its more likely to be faster on a dsp
than a fpga

Have a try at doing a design on both dsp and fpgas.

Can get dsp eval boards from the chip manufacturers and others

http://www.analog.com/processors/index.html

http://dspvillage.ti.com/docs/dspvillagehome.jhtml

freescale (was motorola)
http://www.freescale.com/webapp/sps/site/homepage.jsp?nodeId=012795


If you want an fpga board to test on
xilinx has a spartan3 starters kit for US$99
http://www.xilinx.com/products/spartan3/s3boards.htm

A useful tool for generating digital filters for fpgas
is http://www.winfilter.20m.com/  still need to know
vhdl(also does some nice plots)

Alex