Andre_P
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Re: FPGA Stuff ?

Sat Jan 14, 2012 10:34 am

FatBuzz said:

My understanding is that there are lots of front end tools available but few if any free tools, other than those supplied by the silicon vendors, when it gets to the place & route phase.

If I am wrong please tell me I'd be interested in trying them out.

For Xilinx think of Spartan6 as the entry point.  The Avnet LX9 microboard is $89.  The one I used, as I moved on from Spartan3A, was the Atlys LX45 board $199 for acedemic students.


I think you are right, the back end doesn't exist as far as I know on Linux. I'd be interested to see if you hear of anything as well .

Not as familiar as I would like to be on the really low entry point stuff from any of the vendors. I'll have a look. $199 is fairly steep and $89 again fairly steep for a student, especially ones still at school. I wonder if they will ever get it down. We can live in hope .

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rurwin
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Re: FPGA Stuff ?

Sat Jan 14, 2012 10:54 am

Another possibility for exposing students to FPGA would be the National Instruments RIO boards. Those are not cheap, but they only cost thousands, which may be attainable for some schools. I suppose it is the sort of investment that my school's acquisition of a RM 380Z was in 1979, and that required that the PTA had a whip-round.

The advantage of this approach is that you can design the FPGA in Lab-view.

I know nothing of VDHL etc., but I was able to program one of these things to be a simple 8-bit computer quite easily. That would be an interesting project for a student - to implement the fetch-execute instruction cycle and a usable instruction set. Then they can program a computer that they designed and built.

Regarding long synthesis times, my program builds in around half an hour on an oldish  dual-core 2GB machine, but if it took longer it would be a shoe-in for the A-level question about suitable jobs for batch-mode execution.

Tomo2k
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Re: FPGA Stuff ?

Sat Jan 14, 2012 2:46 pm

Oh no, not LabView. Anything but that!

I'm trying to remember what it was that I was shown at University for FPGA design - it was a visual development tool not too dissimilar to Crocodile Clips or the SPICE diagramming tool where you draw out the hardware logic blocks.

Pretty sure we were using Altera FPGAs.

I never learned any VHDL or Verilog, and I always wanted to do more stuff with FPGAs but never got the chance. Just the one project at University.

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johnbeetem
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Re: FPGA Stuff ?

Sat Jan 14, 2012 9:20 pm

Andre_P said:

Hi John,
I think we are going to have to agree to disagree on stuff there, but agree on a lot as well .

Personally I'd prefer to use simulation with a LOT of testing prior to hitting the synth button. That's not just because of my ASIC background...


Oh yes, ASICs absolutely require lots and lots of simulation since the penalty is so high for making a mistake.  One of the things I find so great about FPGAs, especially SRAM-based FPGAs, is that you can so easily modify the design and try again.  I think of FPGAs largely the same way I think about running a C program.  The FPGA is the machine language.  Yes, I suppose that when I write a C program I could simulate it in an interpreter before running it on real hardware, but that would be silly, right?  But I do appreciate that FPGAs are not quite the same thing.

Another consideration is that I've always been on my own designing FPGAs.  I think the ideal situation is where you have one person design the FPGA logic and someone else write the simulation test bench = input stimulus and expected results.  That way you have a friendly rivalry between the person trying to make the logic work and the person trying to break it, and the simulation dude does not have any assumptions about how you designed the logic.  We did this with the only ASIC I've ever designed, and it worked perfectly.  Plus we had to have input stimulus for testing the manufactured parts.  This was a fairly simple LSI logic gate array using the same silicon as the gate array in the IBM PCjr but of course different metal interconnect and package.

It also depends on the size of the FPGAs.  All of my designs have been for cost-sensitive products where I'm using 50K - 200K gate FPGAs, so tool turn-around is at most a few minutes on a reasonable PC.  It it takes hours to run place & route, then simulation becomes a lot more attractive.


However it is easier in an ASIC flow, you do actually get to see the gates at synth. FPGA yes you are VERY MUCH hostage to fortune with revision levels of the tools. I have almost been driven to tears by the tools you speak of. I have seen them generate incorrect logic which is so VERY VERY scary.


Tool regression with Xilinx is a very real problem.  Fortunately, you can download "classic" versions of the tools, so get the tools that were written for the parts you are using.  For example, whenever I do Spartan-IIE or 9500XL CPLDs I always use WebPack 5.2.  Wow, it runs fast!

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meltwater
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Re: FPGA Stuff ?

Thu Feb 02, 2012 9:46 pm

All this sounds very interesting, it's something I've been wanting to try out.  Unfortunately the dev boards do sound expensive, but I like the suggestion of downloading the tools and simulating instead.

Is there anything which could be done on the RPi, with some basic PLA/FPGA/ASIC chips?

I know when it comes down to it, a PIC or similar could so similar jobs at that level (or even the RPi itself), but I would be interesting in learning a little about the whole area and at least being familiar with what is involved.  Are there any RPi suitable options, at the RPi type cost?

Shall watch this thread with interest all the same.
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drjohnsmith
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Re: FPGA Stuff ?

Thu Feb 02, 2012 10:40 pm

if you want to have fun with fpgas,

why not use an fpga board.

USD 90 , so more than a rPi ,

http://www.xilinx.com/products.....MB-LX9.htm

but has all the tools etc you need to have a great time experimenting, including a soft processor on the board !

Bakul Shah
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Re: FPGA Stuff ?

Fri Feb 03, 2012 12:26 am

meltwater said:


All this sounds very interesting, it's something I've been wanting to try out.  Unfortunately the dev boards do sound expensive, but I like the suggestion of downloading the tools and simulating instead.

Is there anything which could be done on the RPi, with some basic PLA/FPGA/ASIC chips?

I know when it comes down to it, a PIC or similar could so similar jobs at that level (or even the RPi itself), but I would be interesting in learning a little about the whole area and at least being familiar with what is involved.  Are there any RPi suitable options, at the RPi type cost?

Shall watch this thread with interest all the same.


icarus verilog or verilator should be (hopefully) relatively easy to port. But if you want to play with real fpgas you'll have to buy a real devel board. As already mentioned there doesn't seem to be much open source code that can talk to a real fpga (in the Slipway project @ UCB Adam Megacz had a java library for Atmel At94k bitstreams but that was about it I think).

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Re: FPGA Stuff ?

Fri Feb 03, 2012 1:03 am

I'll give my two cents worth.

I have been doing ASICs and FPGAs (Only Xilinx). I could knock-up a Raspberry-Pi FPGA board which connects to the GPIOs in no time. As usual there are many stupidly small but annoying problems:

What FPGA do you choose? Too much choice

What I/O do you add (Everybody has their favourite HW they want to connect to).

But the biggest of all: cost. Let me give you a quick 10.000 foot estimate.

One time off: Prototype board ~$200. Production boards ~200.  SMD assembly set-up ~1000.

Unit costs: board ~$10 (4-layer, small 50-ish run) Components: $10. (Exclusive FPGA). Then you have to add the FPGA costs and any special I/O connectors plus chips.

All that without charging any hours. If you have a run of 50 boards you get to a base cost of ~$50 (without FPGA, I/O, testing, solder, solder paste stencil,actual assembly, shipping and you have to find somebody to do all the work Pro-Deo).

So all you have to do is find about 50 people who can agree on the FPGA and the I/O each willing to pay ~$75-$150 dollars (Price depends on FPGA chosen). If you are still alive after that battle, talk to me again with hard figures and I will see if I can knock out the 50-ish boards in about eight weeks time.

You will still need a big PC to do your HDL design but at least you have a Raspberry-Pi which will talk straight to your FPGA. (Oh, and I suggest you build as first try an SPI slave interface. I think you can write on of those in ~15 lines of HDL.)

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meltwater
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Re: FPGA Stuff ?

Fri Feb 03, 2012 11:42 am

My idea of low cost is different, my main reason being there is a big chance that it'll sit in a draw doing nothing if I don't get round to using it.

[as an aside: Is this of any use for experimenting with, anything else required? http://uk.farnell.com/digilent.....tt=2061840 ]

The issue I can see here is that in order to do FPGA stuff there are a number of things you have to have available when you do it (high end PC, non-cheap dev board, installed tools and plenty of time).  Each of those push it out of the casual hobbist window (such as I am in - unless my work requires otherwise, it'd be good to build background knowledge).

Now is there a need for a RPi FPGA board? Perhaps there is...but it seems like it is not the platform suited for design of the FPGAs itself.

Could there be value though in creating a shield which holds an FPGA which can be reconfigured by the RPi itself?

If it is possible to do so, you'd then have a re-programmable hardware block which could be switched on to suit a range of applications on the fly.

Could be an interesting way to work...probably impractical though.

Also I've no idea how the abilities of FPGAs scale to cost etc, would a $10 part ($20 board) do anything useful, or are we looking at $50+ for a good FPGA?

As a learning tool, on a much smaller scale, is there a programmable logic chip which effectively allows you to program hardware logic circuits, such a implement a shift-register, or a memory cell etc (I know this can be done with software simulation, but hardware makes it much more rewarding).  OT from FPGA, but an excellent way to learn about hardware logic circuits...I've not worked in this area so I don't know what is available.

Gert said:


So all you have to do is find about 50 people who can agree on the FPGA and the I/O each willing to pay ~$75-$150 dollars (Price depends on FPGA chosen). If you are still alive after that battle, talk to me again with hard figures and I will see if I can knock out the 50-ish boards in about eight weeks time.


That might not be that impossible (in theory)...if you consider asking 5 universities which are interested in teaching FPGA design, it'd be easy to expect each to invest in 10 boards (if they were serious about teaching).  Of course, when there are 1million+ RPi's out there, perhaps there would be plenty of interested parties.

But then what advantage would that have over a normal dev board?
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Hugh Reynolds
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Re: FPGA Stuff ?

Fri Feb 03, 2012 12:12 pm

I still think you would be better off, time, effort, finances, infrastructure, buying the Atlys LX45 board.  (I have no connection to Atlys etc.)

Make up a good cable so you can get into the Spartan by SPI.

QED.

MrEngman
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Re: FPGA Stuff ?

Fri Feb 03, 2012 2:53 pm

Haven't seen it mentioned yet so for those interested in FPGA's try http://opencores.org/

Loads of open source FPGA projects.

The OpenRISC project has several inexpensive development boards with either Altera or Actel FPGA's and there is software available for free download. e.g VirtualBox disk images with complete Linux setup and development tool sets.

The FPGA manufacturers also generally have free versions of their development tools available for Windows and Linux.

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Hugh Reynolds
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Re: FPGA Stuff ?

Fri Feb 03, 2012 3:17 pm

While my experience is with Xilinx devices, I have often been attracted to the offerings from Lattice.

Price and facilities are good.

Only inertia has stopped me.

http://www.latticesemi.com/index.cfm

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johnbeetem
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Re: FPGA Stuff ?

Fri Feb 03, 2012 3:53 pm

meltwater said:

Also I've no idea how the abilities of FPGAs scale to cost etc, would a $10 part ($20 board) do anything useful, or are we looking at $50+ for a good FPGA?
My experience is with Xilinx Spartan chips, which are specifically designed for low-cost, high-volume applications.  IMO you can get an amazing amount of logic for a modest price.  For example, the Spartan-3A costs USD 7.67 - USD 12.17 for a 50K gate device (quantity 1, commercial temp) depending on package.  A 200K gate device costs USD 15.50 - USD 22.00.  These are today's prices at avnet.com.

By 200K gates, Xilinx means that it's equivalent to a gate array with 200,000 gates.  The 200K gate device also has quite a bit of high-speed dual-port on-chip SRAM, which can be used for internal FIFOs, ROMs, and other fun things.
OTOH, the Xilinx Virtex parts are very expensive.  I think Xilinx tries to get you hooked with the Spartan series and hopes that you won't be able to fit your design into the Spartan and have to switch to Virtex.  But if you're a reasonably clever designer and learn how to fool the Xilinx tools into generating the logic you really want, you can do amazing things with 50K - 200K gates.  It's all a question of partitioning your system well into fixed hardware, programmable hardware, and software.  Unfortunately, many organizations have high walls between these three functions so the partition is not done well and Xilinx is able to sell larger, more expensive FPGAs.

Hugh Reynolds
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Re: FPGA Stuff ?

Fri Feb 03, 2012 4:46 pm

John Beetem said:


meltwater said:


Also I"ve no idea how the abilities of FPGAs scale to cost etc, would a $10 part ($20 board) do anything useful, or are we looking at $50+ for a good FPGA?


My experience is with Xilinx Spartan …..A 200K gate device costs USD 15.50 – USD 22.00.  These are today"s prices at avnet.com.

……


Moving on to Spartan6 XC6SLX16-2CSG225C you would get almost 800K gates for the same price ($22).  A bit short on pins for my designs but a hell of a device for the price.

Currently I'm using XC3SD1800A-4FGG676C at $85 (1800 gates) but could fit in an XC6SLX45-2FGG676C at $65 and it would be a much better design for the change thanks to the built in hard coded DDR2 blocks.  Then I could throw out my hand coded SDR 128bit wide homebrew controller!!!

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Re: FPGA Stuff ?

Fri Feb 03, 2012 8:00 pm

meltwater said:

As a learning tool, on a much smaller scale, is there a programmable logic chip which effectively allows you to program hardware logic circuits, such a implement a shift-register, or a memory cell etc (I know this can be done with software simulation, but hardware makes it much more rewarding).  OT from FPGA, but an excellent way to learn about hardware logic circuits...I've not worked in this area so I don't know what is available.
Yes, you can use a CPLD (Complex Programmable Logic Device).  I've done a lot with Xilinx XC9500XL CPLDs, but would also consider Xilinx Coolrunner-II nowadays.  These are reprogrammable big brothers to the old Monolithic Memories, Inc PALs (Programmable Array Logic) which were used in the original Macintosh.  Xilinx CPLDs are flash-based -- I think you can reprogram 10K times or so.  CPLD size is measured in macrocells, where each macrocell is a sum of products plus an optional flip-flop, usually limited to an average of 5 or so product terms per sum.  The product terms can have a large fan-in, usually 16 or more inputs with optional complementing.  CPLDs are great for "glue logic" decoding, and fine for learning about logic.  They're terrible when you need a lot of flip-flops or lots of cascading functions of a few input each.

I've never used Digilent myself, but they have a Coolrunner-II 64-macrocell CPLD board for USD 23, also available from Amazon for USD 25.  The board requires a JTAG cable to program.

A 64-macrocell CPLD only costs a few dollars.  You may still be able to get small Xilinx XC9500XL in a 44-bin PLCC, which has wire-wrap sockets available

I don't know what the status currently is for open-source CPLD software.  However, I seem to remember that at least some Xilinx CPLDs may have had the programming bit stream published.  The logic minimization algorithms are nowadays considered a "solved problem" and software based on the Berkeley tools is very likely available.  Otherwise, it's pretty easy to throw together an implementation of Quine-McCluskey.  So it's probable that someone could put together a CPLD design environment that runs completely on RasPi.  Maybe I'll look into it myself when my project gets closer to that point.

FPGA manufacturers are totally paranoid about publishing their bit stream specs.  The excuse given is usually that their customers don't want competitors from sampling the bit stream as it goes into the FPGA and reverse-engineering the netlist.  If you pursue the issue, they direct you to http://www.imaweasel.com.  CPLDs are hard to reverse-engineer since the program is stored inside the chip, so manufacturers can be more open about the formats, though I'm not sure if they have published or not.

An off-beat alternative is the relatively-new Cypress PSoC3 and PSoC5 series.  These are mixed signal analog/digital parts which include multiple 22V10 PALs as components which can be interconnected on the chip.  The PSoC also includes a CPU: 8051 for PSoC3 and ARM Cortex-M3 in the PSoC5.  They almost provide enough information to let you program the PALs yourself, except that the last time I looked you could not get information on the routing network.  They also directed me to http://www.iamaweasel.com.  So you have to use their PC-based software and subject yourself to their EULA.  It's really too bad, as the PSoC5 is really cool hardware.  Sigh.

Piw32
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Re: FPGA Stuff ?

Fri Feb 03, 2012 9:34 pm

Here http://www.seeedstudio.com/depot/papili ... th=132_192 you can buy a $65 FPGA board :

The Papilio One 500K comes fully assembled with a Xilinx XC3S500E and 4Mbit SPI Flash memory.

ayhoung
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Re: FPGA Stuff ?

Mon Apr 09, 2012 5:53 am

You can also check out Terasic's $79 DE0-Nano.

There's great resources on booting linux on this platform, and is probably the best bang for your buck regarding number of logic resources and cost.

http://hackaday.com/2011/09/27.....pga-board/

and some tutorials/resources for getting started with FPGAs
http://www.altera.com/educatio.....rials.html

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johnbeetem
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Re: FPGA Stuff ?

Thu May 10, 2012 8:53 pm

Regarding inexpensive FPGA development boards, here's a new pair of boards for the Lattice iCE40 "Los Angeles" family: $39 for a small board with a 1280-cell + 64Kb FPGA and built-in USB programmer.   I hadn't heard of the iCE40 before -- it seems to be something Lattice got when it acquired SiliconBlue.  The iCE40 looks like a pretty clean and simple architecture, making it quite suitable for students.  As usual, you need a PC to run proprietary tools, but at least they say they run under GNU/Linux.  The USB programming interface is an AT90USB processor.  I don't know if they provide an open way to talk the the AT90USB or if you have to use Lattice tools (or reprogram the AT90USB).

guzunty
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Re: FPGA Stuff ?

Sun Apr 21, 2013 12:28 pm

You might be interested in this initiative I started:

https://github.com/Guzunty/Pi/wiki

Very low cost CPLD kit. I started it to encourage youngsters to dip a toe in with HDL, much as Pi itself is designed to encourage the same with programming.
Guzunty: A fully programmable peripheral you build yourself! https://github.com/Guzunty/Pi/wiki

matib12
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Re: FPGA Stuff ?

Sat Sep 14, 2013 1:08 pm

I designed, prototyped and tested a shield for Raspberry Pi with Spartan3 on board. My aim was different than teaching VHDL, anyway I think it can be a useful tool. I share files with the design via my blog:

http://mbecho.blogspot.it/2013/09/raspf ... berry.html

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peepo
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Re: FPGA Stuff ?

Fri Jan 10, 2014 9:15 am

HDL? FPGA? why LOGiPi @ kickstarter?
http://www.raspberrypi.org/forum/viewto ... 34&t=66029

guzunty
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Re: FPGA Stuff ?

Fri Jan 10, 2014 10:26 am

Is that user name a Flanders and Swan reference? :-)

Please see my answer on your cross post thread.
Guzunty: A fully programmable peripheral you build yourself! https://github.com/Guzunty/Pi/wiki

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peepo
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Re: FPGA Stuff ?

Fri Jan 10, 2014 12:36 pm

handle references are http://www.peepo.co.uk http://www.peepo.com http://www.gnote.org
in chronological order ~1998-2014
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johnbeetem
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Re: FPGA Stuff ?

Wed May 28, 2014 11:28 pm

For those interested in reasonably-priced FPGA boards, Gadget Factory has just begun a Kickstarter on their new Papilo DUO board, which is a combined Xilinx Spartan 6 FPGA development board and Arduino clone:

https://www.kickstarter.com/projects/13 ... ab-for-mak

Along with a Spartan 6 LX9, Papilio DUO includes an Arduino Leonardo clone using the Atmel ATmega32U4. The board also has 512KB or 2MB SRAM, 64Mb SPI Flash, and an FTDI 2232H USB 2.0 communications chip for JTAG and serial communication with the FPGA.

The Kickstarter is an interesting read. It targets new FPGA users who are leery about having to learn a new language like Verilog or VHDL. Gadget Factory shows an approach using schematic editing as an easy way to get started with FPGAs.

Note: my only affiliation with Gadget Factory is as a happy customer who recently acquired a Papilio One 250K which I think is a great little board, and at US$38 a great way to get started with FPGAs.

icyberns
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Re: FPGA Stuff ?

Sat Jan 12, 2019 4:51 am

Hey so I am still wet behind my ears on the subject of Linux... Verilog.. FPGAs and programming in general.
My goal is to utilize the Quartus II Prime Lite free download software in order to program my Altera FPGA device on my Raspberry Pi 3 B+
It does not work I believe due to the OS Rasberian not being able to compile the .exe and setup file and I think that was mentioned in the chat.

What can I do to make it work or do I have to switch OS? Maybe Ubunto?

I am very interested in VDHL and the other things that you were talking about btw it is very interesting!
Any resources that you could give on the subject I would appreciate, or how to get started.
Right now I have all the gear of a professional soldier but have never seen battle!!

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