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[SOLVED] Seeking help choosing an FPGA develoment board.

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Robo_Pi

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Hi, I would like to learn about FPGA and whether or not it may be useful for my intended purposes.

The main purpose I have in mind right now is to use the FPGA for pattern recognition. It's my understanding that many people have been using FPGAs for this purpose already.

I have the following constraints. Mostly financial. I'm a hobbyist working in robotics. I use Raspberry Pi and Arduino boards to do most of my processing and microcontrolling. I'm looking to add inexpensive FPGA boards to my toolbox. The pattern recognition I mentioned above is one application, but there may be others that I'm not even aware of at this time due to my ignorance of what FPGAs are even capable of.

With all of the above in mind I've been considering the following FPGA boards.

RioRand® EP2C5T144 Altera Cyclone II FPGA Mini Development Board (Price: $23.90)

51PEHhcwwbL._SX425_.jpg

I like the small size and small price of this board at under $20. But I have no clue what its limitations are.

A second board that I've been considering is this one at almost twice the cost at $38:
Waveshare XILINX Spartan-3E Core Board XC3S500E XILINX FPGA Evaluation Development Board Kit (Price: $38.99)

41SdRwr6KLL.jpg

Between these two boards, is one more powerful than the other? Would the Xilinx Spartan 3E be far more powerful than the EP2C5144 Altera Cyclone and therefore well worth twice the dough?

Like I say, I'm new to FPGA and I don't really know what to choose.

My main concerns are cost and footprint. I like a small board that I can tuck away in my robots. And I like a small cost allowing me to purchase several of these over time. So these two boards are attractive to me. I just don't know whether the Xilinx is worth twice the money?

I can actually get the Altera Cyclone II boards for as low as about $15 from other sources. So the Xilinx Spartan 2E is actually more than twice as much. But is it worth it in terms of having a more powerful or more dense FPGA chip?

Thanks for reading.

Other suggestions are welcome too. But please keep in mind that cost and small footprint are two important factors for my applications.
 
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With either of those you'll still need to buy a programmer, which will be anywhere from ~$10 to ~$150 depending on if you buy some aftermarket clone or the actual programmer from the vendor.

You may want to do more research.

Something like this might be more useful:
The miniSpartan3 is our new, low cost, tiny, FPGA kit. It starts at just $29, and there is a more powerful FPGA chip available for $39.

Features:

The Spartan 3A XC3A50 FPGA ($29), or the Spartan 3A XC3A200 FPGA ($39) from Xilinx.
An on-board USB JTAG Programmer to power and program your FPGA.
An on board USB to Serial Interface.
One HDMI output port.
41 digital I/O pins.
A 4-channel analog to digital converter running at 200 KSPS with 8 bit resolution.
4 Mbit SPI Flash.
32Mhz oscillator.
3 LEDs for debugging.
2 DIP switches.
Dimensions:

1.6 inches wide
2.5 inches long
In the same price range of the other two but has the JTAG programmer built into the board, that is something you may want to keep in mind (do you need a programmer). The only issue I see with this board may be the requirement that you power the board from the JTAG. As you want to install it in a robot, you may not want it permanently attached to a computer.
 

Hi ads-ee,

Thanks for the tip on the Spartan 3A XC3A50 FPGA board. I'm only just now trying to get into FPGAs and there seems to be an over-abundance of products to choose from, which is good I guess, but can also be confusing for someone just starting out.

As far as the JTAG programmer is concerned its my understanding that I can get one of those for the Altera Cyclone II for under $10. And then I can use that same programmer for any additional boards I buy. I didn't really look into a programmer for the XILINX Spartan-3E board yet.

My main concern right now is to try to understand exactly how powerful the actual FPGA chips are.

I'm not sure about this but it appears to me that the following might be correct:

The Altera Cyclone II has an EP2C5T144 FPGA chip on it. From what I can make out this means that it has only 5k logic gates? (I think that's what the 5 stands for in the chip number) I'm not even sure what the 144 at the end means.

The XILINX Spartan-3E Core Board appears to have XC3S500E FPGA chip. From what I can make out this means that the FPGA has 500k logic gates? Is that correct? Is so then the Xilinx board would clearly be far more powerful than the Altera board. But I'm not sure if my information is correct.

The Spartan 3A XC3A50 that you just pointed to appears to have 50k logic gates.

So thus far, (if the numbers above are correct) it appears that the Spartan 3E has the most to offer in terms of the actual FPGA chip? It also appears that the Altera Cyclone would be vastly limited in comparison with only 5k logic gates (or whatever that number stands for)? But I don't know if my information is correct.

Am I doing this right?

I'd like to get the most bang for my buck, and based on the numbers above (if I'm doing this right) the the Spartan 3E appears to have the most powerful FPGA chip on it. Also if I can get a JTAG programmer for it for around $10 that would be a one-shot investment since I could use that same programmer to program any future Spartan 3Es I might buy.

I definitely want to get something. But I'd like to make the wisest choice first time around. And right now the Spartan 3E board looks like the most powerful FPGA chip for the buck at 500k LEs (whatever "LE" means). If I'm reading these chip numbers correctly.

I like the Altera Cyclone, but if it only has 5K LEs compared with 500K LEs of the Spartan 3E then the Sparan 3E seems to win hands-down in terms of having more to offer.

I take it that LE means logic units or logic blocks? I don't know what LE stands for exactly but I think it has something to do with how much logic is available on the chip.


So in summary it appears to me that the following might be true:

Altera Cyclone II EP2C5T144 = 5K logic gates or units?
Spartan 3A XC3A50 = 50k logic gates or units?
Spartan 3A XC3A200 = 200k logic gates or units?
Spartan-3E XC3S500E = 500k logic gates or units?

Is this correct?

Is so, the Spartan 3E board looks like the best choice in terms of offering the most programmable logic gates. And the Altera Cyclone looks almost crippled in comparison! Unless I'm doing this wrong.
 

You usually look at the datasheet for the part to determine how many "logic cells" you have.

The EP2C5 is in the first column (captured from the Cyclone II handbook)
Capture.JPG
As you can see there are only 4608 LE (logic elements) and each of those has 1 4-input LUT and a FF, therefore there isn't much logic. Now the Spartan 3 series though uses the inflated equivalent gate count (what ever hand waving BS that means), so the 500K gates really mean you have:
Capture.JPG
i.e. 4656 slices, with 2 LUTs and 2 FFs per slice. So it's only 2x the size of the EP2C5 the other parts you mention are even smaller than the EP2C5. The XC3A50 only has 704 slices! So it's way smaller than the EP2C5.

For any board you are interested in you should get the datasheet/user guide and see what capabilities it has most of these documents have within the first chapter a table like the above summarizing the features. Though you'll have to dig into the architecture to determine what a Slice/CLB/ALM/LE means in terms of numbers of LUTs and FFs.

Both the Cyclone II and the Spartan 3 series are very old (antiquated) parts, the only thing going for them is they are cheaper than the newer parts, but then again a Spartan 6 board (still an old part) that is $50+ will have easily as much if not more usable logic than the xc3s500 (and the part is still supported).

Things like the Arty 7 35T have deceptively large amounts of logic as it uses 6-input LUTs, DSP blocks, large amounts of BRAM, XADC, Transceivers, PLLs, PCIe endpoint. In this case the 35 is once again a marketing number as it seems to be an average of the number of LUTs and FFs so it's half way between the number of LUTs and the number of FFs. Regardless with 5200 slices you get 20.8K LUTs and 41.6K FFs. But to get all this you'll have to fork over $99.

To give you an idea of what the 5200 slices buys you...
The microblaze in a Artix 7 runs around 200 MHz uses perhaps 2000 LUTs and 1800 FFs for a typical configuration. They also have a table entry for running with Linux and an MMU, which comes in at 3653 LUTs, 3218 FFs, and 142 MHz.
 

Both the Cyclone II and the Spartan 3 series are very old (antiquated) parts, the only thing going for them is they are cheaper than the newer parts

In addition, the latest 2 releases of the QuartusII IDE from Altera, do not provide native support for the series below CycloneIII, anymore.
 

Though you'll have to dig into the architecture to determine what a Slice/CLB/ALM/LE means in terms of numbers of LUTs and FFs.

That's why I came here. I was hoping I could just ask a few questions instead of earning my own PhD in FPGAs first. :-D

I'm really just looking to get my feet wet with FPGA programming right now. So maybe that Cyclone II board will do for starters.

Both the Cyclone II and the Spartan 3 series are very old (antiquated) parts, the only thing going for them is they are cheaper than the newer parts

Right now for me budget is paramount. And since I'm thinking that I might actually end up using several of these boards in my robot projects, keeping the cost down per board is a major consideration. But then again, a low-cost FPGA that isn't powerful enough to do much of anything useful wouldn't be such a great deal either.

My confession to being clueless

I'm not even sure if an FPGA will be useful for me. I just heard stories that they have a lot of advantages over digital processors or microcontrollers when it comes to speeding things up, especially in terms of things like pattern recognition, or "tracking" of objects, etc.

Currently I have no clue how I might even actually use them, but I would like to learn and gain some experience. As I stated in the OP the I found the Cyclone II board attractive because of both the small footprint, and the low cost. I can also get them for around $15. And the JTAG programmer is only about $8.

I don't mind them being antiquated as long as they are still usable:

In addition, the latest 2 releases of the QuartusII IDE from Altera, do not provide native support for the series below CycloneIII, anymore.

Well, that sounds a bit scary because I would hate to buy the Cyclone II boards only to discover that I can no longer find free software to program them. I was thinking the Quartus II IDE would work for the Cyclone II. If that's not the case, then I could end up being up the creek without a paddle. The boards would be useless if I can't program them.

I have an even more antiquated story to tell

I actually already own a very old Xilinx FPGA and CPLD boards. These were quite expensive way back when I got them. But I still have them complete with the programming software. I can play with these boards, but as I say they are seriously outdated.

XS40-005E FPGA


And the XS95-108 CPLD


I still have both of these boards and an old Windows 98 computer set up to program them. So I could just play with them some I suppose. I was thinking of upgrading to something more modern before I waste a lot of time programming boards and chips that aren't even manufactured anymore.

This is why I was thinking of picking up something like the Altera Cyclone II. Ironically, even that is considered obsolete already! This stuff goes out of style too darn quick!
 

Hello,

Have you got any idea what your architecture of the thing you will build shall look like ?
From there you can decide what to put in FPGA or SW and what the requirements for your FPGA should be
(eq no. of pins , adders, multipliers, block RAM and etc)

Take some time to draw a picture of complete thing and what you would like to have in the FPGA.
Concluding from there it could be that a simple FPGA board is sufficient or you need something heavier.


BTW
Waveshare sells modular boards.

**broken link removed**

You can add anything from switches to an LCD, UART and etc

best regards

Simon
 

Often, low-cost fpga boards are designed for education about basic FPGA functions. This makes many dev boards unsuitable as you have no way to get data in/out at high enough rates to be used as a coprocessor. (or primary processor).
 

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