MCU + FPGA - is it still something people looking for?
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MCU + FPGA - is it still something people looking for?

by Dzun on Tue Jun 05, 2012 5:57 pm

Hi all,

I´m wondering whether MCU+FPGA is still something that people are looking for or there´s no need for this kind of designs/boards?
I´ve heard about the Maple Oak long time ago but still haven´t seen any boards. Maybe when compared to Arduino etc. Maple abandoned this idea? Or maybe if there were some tools which would make it easier to use (as it is with Arduino) people would give it a try?

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Re: MCU + FPGA - is it still something people looking for?

by cstratton on Wed Jun 13, 2012 12:12 pm

It's not an uninteresting idea, but it may be a hard requirement to pin down enough to make something marketable at prices comparable to stand alone FPGA and microcontroller boards.

Occasionally you will see a processor board accessorized with an FPGA, but in the only example of this I ever used, versions with the FPGA actually populated had a huge leadtime, so we ended up putting a high end CPLD on a carrier board that was needed anyway.

Often once a project goes the FPGA route, the specific FPGA becomes fairly dominant in the selection critera, and the microcontroller pushed to the background, as the FPGA is often there to provide peripherals not available on-chip, and this makes details of the chosen micro less important. This may lead to:

- A processor core being integrated in the FPGA itself

- the FPGA loosely coupled to a separate processor board, often via SPI (since that's easy to implement in an FPGA, though I've also done asynch serial by implementing a UART in a case where it made more sense)

- No microcontroller, with the FPGA instead connected to a PC, via SPI (bitbang on the parallel port, etc), or a USB interface chip, or USB micro. Increasingly today, you could use a highly capable arm embedded controller (rasberry, beagle, etc) in place of the PC, but like a PC still int he category of hardware you don't want to respin unless you have to or have huge volumes.

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Re: MCU + FPGA - is it still something people looking for?

by Franz Liszt on Wed Sep 05, 2012 12:01 am

My opinion is that an MCU + FPGA is still the optimum system....primarily becaue there are simply too many things that either the FPGA is better at, and visa versa with the MCU. Things like data manipulation...its just easier to write that kind of thing in software in a microcontroller. But then you have logic that needs to be done fast , like digital processing, pattern correlations, or "dataflow" problems, where speed is king. An MCU typically cant even get close to doing those kind of things and say...crank out a result EVERY clock cycle...at 300MHZ. An FPGA is king in that world. In most of my designs for many companies I have worked for since the 1980's, I have usually ended up putting an FPGA and MCU together. Today, everything I do almost needs both. But that's just me...

FYI, here is a board that has both...
Franz Liszt
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