Summer with fpgas

Hi,

I'm a beginner in the fpga world.I've been reading up some of the books listed in this group in other posts, and doing basic designs (like contollers, ALUs etc). Although the books and my school lab have helped me get started with fpga design, I'm far, far away from being _good_ at it. Any suggestions on which direction I should be going in?

IMHO, the only way to get there would be to spend more and more time 'getting my hands dirty' so to say. Books don't help beyond a point.

So I'm also looking for a good fpga board I can use over summer and more....

Some suggestions were the spartan-3 starter kit, XSK40 and the XSK95. Being a poor student, I can't afford anything else (and being a beginner I guess I may not be able to _use_ anything else :) )

Which one would you suggest I should go for?

Thanks, Kunal

Reply to
Kunal
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Kunal,

The "Spartan 3E Starter Board" from digilentinc.com is used by quite a number of schools and universities.

As such, 'google' for this shows 131 hits, with complete courses with labs from University of Arizona, etc. etc.

$149.

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Austin

Reply to
Austin Lesea

The Spartan-3 kit is pretty good, complete out of the box, and you'll find some projects for it around the net. I would spend the extra $20 to get an XC3S400 chip on it though (get it from Digilent rather than Xilinx).

I see they are also offerings the XC3S1000, though you could get that chip cheaper on the nexys board. The nexys board is interesting if you want to play with USB for high-bandwidth things, and it has better digital I/O's. But it lacks the serial, keyboard, and VGA ports of the S3kit. Also, if you go that route you may want to buy one of their great-deal power supplies and parallel port programmer cables so you aren't completely dependent on the USB for power and programming.

Which brings up the point: if your development computer doesn't have a parallel port, get they nexys rather than the s3kit.

Reply to
cs_posting

Unless someone really needs an S3E chip, I might stay away from that board, as part of its schematics (around the USB chip) are withheld, limiting your options for programming and communicating with it to what is officially supported or laboriously reverse engineered.

Reply to
cs_posting

In fairness, I should add the substantial memories and display to the "unless one needs" consideration.

All of these boards have tradeoffs of goodies vs. issues

Reply to
cs_posting

How totally pathetic - who could possibly gain anything by hiding part of a devboard....

Reply to
Mike Harrison

I've recently come across the Altera DE1 board which also seems like a very good deal. Among its good nice features are:

512Kbyte SRAM memory - No need for a cumbersome SDRAM controller or DDR controller Audio input/output - Haven't found this on a low end Xilinx board yet SD card interface - Nice for storing audio files for the above :) Lots of leds Downside: No Ethernet.

(I'd love to hear about a Xilinx board with Audio input/output in the same price range. We are interested in such a board for a course we are giving since it would be nice if students could afford the board.)

Personally, I would also like to point out that getting DDR memory to work is not straightforward. If DDR memory is your only external memory (and you are building a design which needs more memory than is available on the FPGA) you are going to be in trouble. (Unless you buy the EDK which can automatically generate a design with a DDR memory controller for you.) DDR is complicated by the fact that you have to run it quite fast if you are going to follow the standard.

In contrast, SRAM is very easy to interface to and SDRAM can be done with a moderate effort.

/Andreas

Reply to
Andreas Ehliar

Hey guys,

thanks for the advice. I do have a parallel port on my machine, but I'd rather also be able to program from my laptop. The S3E sounds really great, but it's probably got more goodies than I can pay for :). I'd probably go for the nexsys one, though not without another thorough look at both the S3E starter as well as nexsys.

Thanks all the same!

cheers, Kunal

Reply to
Kunal

Mike,

Well, the blank sheet (3) is for the USB interface.

Not sure why...

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Is the previous revision of the schematic, with page 3 shown.

If it is proprietary (now, in this revision), then I suppose someone else owns the USB interface design, and they have rights to it we must protect.

Still, I do find it odd.

If someone really wants to look at a USB to FPGA interface, not only is there the previous revision of the board schematic, but thousands of them out there on the web.

Austin

Reply to
Austin Lesea

Andreas,

If I have my choice, I hope he chooses a Xilinx board.

I do not mind one bit that he uses an Altera board to learn about FPGAs: it will be his first job that will determine who he will get to use, it will probably not be his choice!

So, the more that know how to use FPGA's, the better.

I only offer up the Digilent board because there have been tens of thousands sold to students. The resulting ecosystem has some benefits.

Austin

Reply to
Austin Lesea

Hey all,

Thanks a lot for your help! Andreas, your Altera DE1 board seems really interesting especially with the audio out. But I guess Austin is right too. If xilinx is indeed a more popular choice for students, there'll probably be more accessible projects, docs etc. to help me out. Anyway, I'll try and find out how popular this altera kit is too, and then come up with a conclusion.

That aside, the nexys one looks good to me, primarily because it has the usb port too, and also 'cos it's all i can afford right now :(. I'd love to have the S3E, but...............

Thanks a million once again! cheers, Kunal

Reply to
Kunal

I think there's something special that happens when a serious get-your- feet-wet but be able to "really do something" version of a technology is available for general purchase for ~$100.

Reply to
cs_posting

Actually, that schematic is newer and the USB interface page is now not just blank, it's completely gone. Pg 3 now shows something different.

True. Some enterprising individual has reverse-engineered the USB interface and re-written the Cypress USB firmware, as well as the CPLD code to provide an open-source USB download capability. It's not as fast as the code that ships with the S3Esk though.

Eric

Reply to
Eric Brombaugh

The Nexys is a pretty decent board for a beginner, I think. The Spartan

3E looks a little bit more daunting with all of the extra gizmos. If you have a professor/possible mentor who knows a lot about these things, then you'd be fine either way.. if you don't have anybody to refer to when you're stuck on something, I'd recommend a simpler board.

I have to say I'm not terribly impressed with some of the add-on boards: for example, the analog VGA RGB signals are generated by four digital inputs going into various resistors, combined with direct analog addition.. seems kind of cheap for what they charge for it, but I have tested it out, and it does actually work. Also the documentation on their graphic LCD board is quite terrible.. nowhere on digilent's site is there any information on what the interface is, you can find the site of the Chinese company that made it, but their documentation is also really spotty. These are kind of specific complaints.

I do like the breadboard that connects to the hirose board-to-board connector, though I haven't used it yet.. it seems handy.

Reply to
Steve Battazzo

The Spartan 3E starter kit has dual-channel A/D and D/As. MHz+ sampling rate per channel. You will have to add audio amplifiers, probably, but that's no big deal.

The EDK has a short time free trial when you buy the starter kit.

I know that Xilinx has a 'Memory Interface Generator' for producing a DDR interface that's free-as-in-beer if you register

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I haven't tried it, and most of what I know is that 'how do I get it work?' is a FAQ on this group.

--
David M. Palmer  dmpalmer@email.com (formerly @clark.net, @ematic.com)
Reply to
David M. Palmer

IMHO this argument for a student using the kit is somewhat absurd. I work at a Government lab tied to a University and see Undergrad and Grad students all the time (we provide a great deal of funding for them).

The USB interfaces is for JTAG download (probably the guts to the Xilinx USB cable). If they are just learning about FPGAs, the last thing they are going to worry about is the mechanism the USB cable uses to download the bitstream.

To make the argument that you options for communicating and configuring are limiting to student the board is just plain wrong. There is spot for a normal JTAG header on the PCB to use the VIII and IV cables. Trust me, most don't really care about how the USB download circuit operates. People just care that they can get the code in the chip.

A student learning about this is not going to spend their first three months learning about how to design a USB interface. They should be spending their time learning about HDL, logic design, simulation, etc.

When it comes to production design, the one would worry about the configuration options. Even then, this board provides you with just about all you need (JTAG, PROM, SPI) to get the device configured.

Reply to
Eli Hughes

The poster is not a student using a school supplied board, he's someone with the personal funding to buy one board and one board only. So it should be something that he can get long term varied use out of. Something that might not be limiting to a studnet who will soon move on to other platforms or courses could be a real limitation in this case. And one of the long term issues with FPGAs is what do you want to do with them - if it involves quantities of data, getting that into and out of the board becomes a challenge. USB is a great interface for that - but if its not documented, it becomes even harder than it needs to be.

Great, another cable to buy. Hopefully it at least can accomodate the $12 digilent cable as supplied with the S3Kit (I know nexys can, but that's a digilent-unique product rather than one done for xilinx)

Reply to
cs_posting

You can still be a student and not be at a University. :-) H

I can understand wanting to have information about a PCB, but there is a certain point when you just use what is given. For $150 you pretty much have everything you could need for learning FPGAs. You get a fat FPGA with RAM, FLASH, Screen, Ethernet, a multitude of ways of getting you program to the chip, expansion port and free software tools.

This board would keep just about anyone busy for a long time.

Just because the USB download cable is considered 'closed', I am not sure you can do a whole of complaining for $150. Given that it states in the manual that it is used for *EASY* configuration (just what someone learning needs), I wouldn't think that this would be a deal breaker.

Reply to
Eli Hughes

Someone is Xilinx. The circuit is nearly identical to the Platform Cable USB, and Xilinx seems to be mighty proud of that. Since there's nothing that magic going on in the hardware (the magic is in the downloaded firmware and CPLD code), I would guess that you guys are afraid that someone will clone the cable and cut into your profit.

But as others have observed, keeping part of the schematic of the board secret does make it difficult to use that USB interface for other things than Impact and Chipscope. It would clearly have more value to at least some of your customers if the page was included.

No, it's not in there either.

The point isn't to get some other design for a USB interface. Yes, there are plenty of those. The point is that those of us who have purchased the Spartan 3 or Spartan 3E Starter Boards might like to actually use the USB port on board.

The reality is that if someone really wanted to clone the Platform Cable USB, keeping the schematics of the Starter Boards secret is NOT going to be a signifiant impediment. The secrecy isn't actually in Xilinx' own interest, but rather is counterproductive.

Eric

Reply to
Eric Smith

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