FPGA vs. ARM MCU for floating point operations

That will depend on if you can 'spead' the task. A FPGA can give you a LOT of DSP Cells, and if they can all humm along in parallel, you will get large speed gains. Atmel have some ARM9's with flash at 200MHZ that may get you some more legs....

-jg

Well, some things I can kinda do in parallel... I mean one of the big things that I do is multiply 4x4 floating point arrays with each other. That's a pretty computationally expensive operation. Is that the kind of thing that an FPGA would do well?

The main other things going on on the SAM7X256 (that the FPGA would then have to handle) is there are a couple serial data streams coming in that have to be processed (no math - just parsing text - lots of scanfs), various timers runnings, varous buttons and LEDs that need to be monitored and controlled, and that's just about it. Oh, and it also is doing a large amount of CAN communication. There seems to be an open source CAN core though - so I figure I'm probably OK there...

-Michael

why not use a ARM with a vector floating point coprocessor, I think it does single cycle floating point multplies

other micros with floating point HW are MPC5554, infineon etc

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The SAM9260A will give you 400 MHz, while beeing compatible with what you have in terms of peripherals. If you run the SAM7X in ARM mode, you are probably seeing max 25 MIPS. Multiplies are 4 clock cycles.

The ARM9 has a faster core and Tightly coupled memory so you can run up to 32 kB of SRAM with 1 clock cycle access, and 32 kB instruction cache with 1 clock cycle access. Then you have a V5 architecture with 1 clock multiply, I think it will give you at least 20 x performance boost.

No CAN controller though.

The AVR32 core can do up to 4 x 8 bit multiuples per clock cycle, or 2 x 16 bit per clock cycle, and it has the same peripherals as the SAM7X. maxes out at 150 MHz though.

There is an ARM9 + 1 Gflops floating point DSP coming, I have a development board, but I am afraid that the compiler is not open source.

--
Best Regards,
Ulf Samuelsson
This is intended to be my personal opinion which may,
or may not be shared by my employer Atmel Nordic AB

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X.

Hi Ulf - unfortunately, none of the solutions you mentioned has CAN. Being able to easily add CAN (or anything else, for that matter) to an FPGA is my big draw to the FPGA world. I've used external CAN controllers in the past - but that adds in a lot of overhead for the processor that I would like to avoid. The whole parallel processing thing is also really nice sounding...

You know - when I heard about the SAM9X parts coming out - I was so excited thinking it'd be essentially the same chip just with an ARM9 and maybe some extra added bonuses. But the lack of CAN really makes me sad.

Thanks,

-Michael

?? Why should an external peripheral, take more overhead than an internal one ? In fact, if that external peripheral is a small CAN uC, you should have LESS overhead.

Work from the hardest problem first. CAN has many solutions, and there are many CAN uC that can slave. The Floating point load sounds the hardest to meet, so crack that first.

TI have just released some higher end OMAP devices.

If volumes are small, FPGAs are nice to work with as an essentially 'soft' solution.

-jg

Hi,

If you only using single-precision floating point, you can use MicroBlaze with a FPU. It has decent floating-point performance.

There is also tons of other peripherals that you can add to MicroBlaze.

Göran Bilski

"There is an ARM9 + 1 Gflops floating point DSP coming,..."

This one has two CAN controllers... No open source compiler for the DSP though

--
Best Regards,
Ulf Samuelsson
This is intended to be my personal opinion which may,
or may not be shared by my employer Atmel Nordic AB

What package, and Memory ?

-jg

It is BGA, but the development board will be in the form of a CPU Module, (70 x 80 mm) with 16 MB NOR Flash

256 MB NAND Flash and 64 MB SDRAM and a PHY. There will be 3 x 120 pin FCI Bergstak connectors on the module. There is also a baseboard with normal connectors.

This means that anyone can use the part, even if they do not like BGA.

I have a module, but there are not a lot around at this time. Runs U-Boot & Linux.

--
Best Regards,
Ulf Samuelsson
This is intended to be my personal opinion which may,
or may not be shared by my employer Atmel Nordic AB