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Topic: Floating point maths processor (Read 1 time) previous topic - next topic

EVP

Is there a convenient way to add a floating point maths processor to a arduino mega. Preferably with library's already made. I have a memory of seeing such a thing but cant for the life of me find it now. Is it a viable thing to implement or is it over complicated for 8bit avr's

retrolefty

Check this one out. It does have arduino library support avaible.

http://www.sparkfun.com/products/8129

EVP

Absolutely spot on, just what i wanted cheers retrolefty.

el_supremo

I've just bought one of those but haven't had time to play with it yet.
If you buy one and get it up and running let me know :-)

Pete

retrolefty

This chip/product has been avalible for several years now but I haven't read any first hand accounts from users on this site. I would be interested in some actual benchmark timing comparing arduino floating point math Vs what this chip can do. That chip is not a true hardware floating point processor but rather just a microcontroller with firmware floating point routines, plus a whole lot of other unrelated features, so the improvement in speed may not be as large as one might expect from a true hardware FPP. But as I said I've read of no independent users here using the chip.

Lefty


el_supremo

I wired up the uM-FPU and got the great circle distance example running.
If I can figure out how to get it to do a 64-point FFT, I will be able to do some benchmarks.

Pete

Nick Gammon

I just ordered one, so we'll see.

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That chip is not a true hardware floating point processor but rather just a microcontroller with firmware floating point routines ...


But when they say the chip has "firmware" on it, it sounds like you are right. Still I suppose it might conceivably save having to spend your own program memory implementing this stuff. And maybe it runs concurrently with your own program.

retrolefty


I just ordered one, so we'll see.

Quote
That chip is not a true hardware floating point processor but rather just a microcontroller with firmware floating point routines ...


But when they say the chip has "firmware" on it, it sounds like you are right. Still I suppose it might conceivably save having to spend your own program memory implementing this stuff. And maybe it runs concurrently with your own program.


Oh absolutely. I'm sure there are probably speed and memory saving advantages to using this device for FP calculations. It's just that I've never seen a benchmark test published showing a comparison Vs gcc compiled FP calculations as performed on a 16 mhz arduino. Equally impressive is all the other non math functions and features they have added to the package. It's just somewhat puzzling that there hasn't been much first hand experience reported about the product in this forum, as that chip has been avalible for I think a couple of years now, and an earlier version longer yet. Even SparkFun carries it so it's not like there is an availability problem. It would certainly make a nice component to add to a shield along with maybe a RTC and other general purpose devices. Maybe it just needs more or better publicity? Looking forward to your report and impressions on the device once you get a hold of it.

Lefty

Nick Gammon

I got the chip today, and after a false start due entirely to my foolishness got it working as advertised.

From what I have read so far you can download something like 256 "instructions" to be performed, and I gather you can do something else while that is happening. So if you had to do a lot of complex calculations (eg. on analog data) the chip could be doing that while you took more samples, or displayed the, or something.

The default clock speed is almost 30 MHz so presumably it does what it does faster than you could at 16 MHz.

It also has two 10-bit ADC converters so that in itself could also be useful.

I'll set up some more detailed timing comparisons over the next few days.

Graynomad

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I'll set up some more detailed timing comparisons over the next few days.

Be interesting to see how it goes.

If one gets clever with code to make the most of the multi-tasking it could be nice.

______
Rob
Rob Gray aka the GRAYnomad www.robgray.com

Nick Gammon


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