Low Cost Hardware Flaoting Point processor? whats available

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I hate to bring electroncis back into this newsgroup, but I need to
find a low cost FPU to interface to a Rabbit 2000 processor. Having
done no embedded hardware design in the last 3-4 years I have found
myself already drifing away from current trends.

As for the exact precision, no sure at this stage. Still investigating
and open on this one. I prefer to avoid DSP's if at all possible and
need something that will interface to an 8 bit wide General IO port on
the rabbit, so bitbashing serial would also be fine.

All i can find on google is ARM's and DSP's, which are a bit of an
overkill. If it comes to this a complete redisgn will be done, which I
would dearly love to avoid.

Suggestions?

Andy

Re: Low Cost Hardware Flaoting Point processor? whats available



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I am sure you asked google,
and found this already


http://micromegacorp.com/umfpu.html



Re: Low Cost Hardware Flaoting Point processor? whats available



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I had a look at this, but I have noticed that they supply no timing
specs, which leaves me a bit hesitant. I have emailed them, so I will
se what they send back before I pass judgement.

The other problem i see it that they look like quite a small
operations, which worries me a little. Considering I will only be
needing around 150-200 units, this may or may not present a problem

Re: Low Cost Hardware Flaoting Point processor? whats available



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Its looking like I may need double precision, so the suggested device
is out of the question. Its looking more and more like a DSP solution
is needed.

Re: Low Cost Hardware Flaoting Point processor? whats available


On Mon, 09 May 2005 16:19:03 +1000, The Real Andy
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How about one of the 18 series PICs running at max. clock (40MHz?)
and doing it in software? Don't Microchip also do a pseudo DSP PIC?

Mike Harding


Re: Low Cost Hardware Flaoting Point processor? whats available


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Well, then I guess you have already consulted google and found a comparision
between
the micromegacorp unit and some other units, and there will be the info , so
I wont bother.



Re: Low Cost Hardware Flaoting Point processor? whats available


I presume you have time invested in the Rabbit code. How about a small DSPIC
as a floating point accelerator. Not sure how large the FP lib is, but an
SPI-based accelerator isn't out of the question, without messing with your
Rabbit too much.

There are a few DSPICs in low vol production-friendly packages.

Then you're poised for a complete redesign to DSPIC next time.... :-)

-Andrew M



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Re: Low Cost Hardware Flaoting Point processor? whats available


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investigating
on
I

If you are happy with a bit banged serial/8bit parallel interface then
I presume that throughput isn't a primary factor?
Are you offloading single calculations, or performing a bunch of calcs
at once and then returning a result? For former is best done in the
Rabbit in real time otherwise the overhead will likely be too much. The
later is best served by a second processor or DSP rather than a
dedicated FPU chip I would suspect. I guess that's why there ain't too
many dedicated FPU chips these days.

How about a second Rabbit processor, it ain't no slouch in the FP
department. Rabbit's aren't cheap modules though I suppose. Or else a
DSPIC as someone else mentioned. I haven't used the Rabbit for a few
years now, but I vaguely remember about dual procesor capability where
you could tie the two together?

I remember many (4-5) years ago there being a pre-programmed PIC chip
which was a dedicated serial interfaced FPU, but I can't remeber the
name or find the link...

Dave :)


Re: Low Cost Hardware Flaoting Point processor? whats available


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and
which
then
calcs
The
too
where

Found it:
http://www.micromegacorp.com /
uM-FPU

Don't think it's the exact one I remember, but is the same thing.

Dave :)


Re: Low Cost Hardware Flaoting Point processor? whats available


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Doh. Already listed and discussed.
Guess that'll teach me to read the whole thread!

Dave :)


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