SimmStick FPGA module

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Hi all,

I'm thinking about a new board for JOP (or MB, NIOS). The board should be small
and
cheap (below the S3 Starter Kit). It should only contain the absolute necessary
parts for a
CPU design. Here is the suggested part list:

    FPGA: Cyclone EP1C3 or Spartan XC3S200
    256Kx16 15ns SRAM
    2 MBit serial Flash
    3.3V linear regulation
    switching regulator for the core voltage
    20MHz clock to the PLL input

I've not yet decided about a X or A device.

A remaining question is about the form factor. I still think it makes sense to
build
the board as a module that can be integrated in a board with the peripherals
(similar
to the ACEX and Cyclone modules I've done). There are two 'standards' available:

1.) SimmStick, where the boards are designed as the 'old' PC SIMMs (see [1]).

2.) The 'Basic Stamp' design is a board in the form of an old 40-pin (or less)
DIL IC.
    An example (from a Java processor competitor): [2]

For a Java solution in an FPGA this board should beat the Systronix aJ100 Java
processor
modules (JStamp or JStick [3] - they have both form factors) in performance and
price.
One nice thing about the SimmStick is that there are plenty of I/O boards
already available
(see [4, 5, 6]).
It seems a relative 'old' design, but it's a bus and I can build my first JOP
cluster with those
boards ;-)

What do you guys think about this idea? Does it make sense to build a another
FPGA board?

[1]  http://www.simmstick.com /
[2]  http://jstamp.systronix.com/jstamp_photos.htm
[3]  http://www.jstik.com /
[4]  http://www.dontronics.com/dt.html
[5]  http://www.hobbyengineering.com/SectionSS.html
[6]  http://www.simmstick.com/simmstic1.htm

Martin
----------------------------------------------
JOP - a Java Processor core for FPGAs:
http://www.jopdesign.com/



Re: SimmStick FPGA module
Hi Martin,

Nice to see that some of my project are still live - I am the "inventor" of
the "SimmStick(tm)" standard :)

Please see my SHORT first comments below..

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small and
necessary parts for a
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-- here I would like to argue a lot!
I understand that JOP runs ok in that memory, but... all the rest  (if using
XC3S200) is uCLinux ready, except memory is not enough, so I would use 1
16bit SDRAM chip, not SRAM
XC3S200 is large enough to hold ucLinux ready MicroBlaze setup.
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-- again the 2MBit is enough for config, not for OS image, so if there would
be some means of having more, that would be nice, sure thats an price issue
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for a small FPGA linear regulator is ok, too cheaper sure burns more energy,
Trenz S3-1000 module as example has small linear regulator supplying max
0.9A for core
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NEEDED 5V compliance quickswitches !!!
all new FPGAs are not 5V tolerant and for both mech standards simmstick and
stamp 5V compliance is highly recommended to have, its a pain for
manufacturer but a big + for the user
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hard decision hugh?
answer is simple. BOTH
it doesnt cost so much more todo both variants, you may supply more support
for either A or X as of your preferences (or customer interest) but from the
hardware build expenses its even cheaper (per board) to order a combined pcb
patch

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sense to build
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peripherals (similar
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available:
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[1]).
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less) DIL IC.
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You mean Parallax or those other guys? There are actually several stamp like
clones thing.
the stamp form factor is more challenging as the pcb are is very constrained
:(

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Java processor
performance and price.
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already available
JOP cluster with those
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hm if you make the simmstick form factor board, here is a deal - I will
donate all my leftover simmStick stuff that includes some connectors and
protoboards etc, you can use all those boards and stuff as promotional bonus
give away for the early customers :)

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another FPGA board?

hm.. I just recently looked at the parallax pricing.. still selling basic
interpreter for $49 (or more!) and still doing business. highend stamp are
in $99 range! So a fpga plugin module in $99 range, sure it might be
business idea still

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Re: SimmStick FPGA module
Hi Antti,

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Sorry, I should have given the credits to you!
BTW.: Is this format still alive?

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However, SRAM is way much simpler to handle. I think SDRAM is a pain.

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Could be an option. However, handling options are a pain in the manufacturing.

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The 3.3V linear regulation is only for the IO. The core voltage gets a switching
regulator. If you are using this module in a 3.3V SimmStick bus you can go
without the linear regulation on board (will be a sloder jumper)

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That's again pain. I was thinking about being not 5V compliant. It's time to stop
these 5V designs! Or, add series resistors - bad for the bandwidth.

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I don't think it's possible to build one pcb for both. I want the module to be
small.
As small as the 9 part SIMMs (79mm x 21mm).

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Yes, I would need parts on both sides of the pcb. However, it's only a little bit
more expensive in the manufacturing.

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That's a deal :-) However, it's an indication that you don't buy ino the bus
anymore.

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Probably will give it a try.

Martin



Re: SimmStick FPGA module

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of

no problem.
hm alive I think yes, I a havent be doing much (read anything) for years but
there are still products around

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using
yes no, once the SDRAM controller is once configured it works, but agree
from the
ip core side its more painful, still 4MByte of onboard RAM would just GREAT!

hm I think it is possible to make a layout for either 54TSOP sdram and SRAM
(that would be beneath it) please consider..
that would be a mount option, :( but well I would consider.
I have several FGPA boards with 0.5MB RAM, and all of those are
"bad" as they can not boot linux :(
hm I have 40 PCS of those SDRAM overleft  in cut tape, again if there is
place to solder them those are yours for the project...

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would
issue
manufacturing.
yes I, know the manufacturing options are pain, its a mistake I have done
and
learned as well, I wanted the first simmstick so be cheap and flexible by
providing
lots of mounting options, that was bad actually would have been better to
add it all and sell a bit higher

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energy,
switching

hm ok, besides for spartan at least 2.5V is also needed !! even if 2.5 ios
are not used that an additional small regulator :(

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and
to stop
yes pain, would be so much easier to go only by 3.3 or 2.5

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support
the
pcb
to be small.
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yes that should be the small board, I meant to produce two different
boards!!
(not one that can be used with both FPGAs)
each time you order PCB so you always get both X and A, if there comes
big overleft of X or A boards you can etiher sell away the remaining plain
PCB or then order the best seller as separate PCB

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(or
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like
constrained
little bit

depends how much you squeeze and what production quantities are.

The original STAMP in DIP28 where partially hand made, the Parallax
people had a barbeque at behind the office and a tin-pot in the middle so
they had a party and at the same time soldered those DIP pins to the
stamp modules - that also in large numbers. I think they dont have those
BBQ anymore but for the long time this was the procedure.
ah old good days ;)

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boards
first
bonus
bus anymore.

not necessarily - I have been occupied.
http://www.case2000.com/gallery/album01
some older pictures of family (part of it) there are now 3 kids.
Anna youngest is 1y3months. sick right now :(

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basic
are

Good luck, and I see what support I can give on the way, there are some
ideas
for SimmStick that I did not realize, maybe its time for them to become
true.




Re: SimmStick FPGA module
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Dontronics sells a range of SIMMsticks:

http://www.dontronics.com/cat_index_hard.html

Leon



Re: SimmStick FPGA module
Hi

Just my 2cents ...


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SDRAM is not that hard and having a lot more capacity is a big plus IMHO, that
worth the extra work.

 
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switching
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Have a look at
http://focus.ti.com/lit/ds/symlink/tps75003.pdf

Really nice little chip ;)


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If there is a spare centimeter square, adding an unpopulated space for another
XTAL maybe.


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stop
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I agree. 5V compliance shouldn't be necessary ... If you need it, just do it in
the
board you're plugging this module into.


Other remarks :
Having a few I/Os routed as differential pair to the connector could be nice




Sylvain

Re: SimmStick FPGA module
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Yes, I will go with the SDRAM. Do you have an idea what chips are used these
days.
I've found Micron MT48LC4M16A2 could be a choice.

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switching
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Nice, but still many external components. However, as it looks like that I will
use
the Cyclone I only need one switched power supply (1.5V).


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Why? You can use the internal PLL. And I'm not using an XTAL, but an integrated
osci.
If you really need a different frequency than you can change the osci yourself.

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could be nice
Do you mean LVDS standard with the termination resistor network?

Martin



Re: SimmStick FPGA module
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days.
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Yes, looks good to me. If you still have spare IO, routing the address lines for
the superior model might be interesting. Maybe there is no more line to route
actually,
I didn't check


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May I ask why ?

The EP1C3 has 2910 L.E., 1 PLL and 60kbits of ram.
The XC3S200 has 4320 L.C., 4 DCM/DLL, 216kbits of ram and 12 dedicated
multipliers


(Note that it's _not_ a A vs X issue ! Theses chips are just not of the same
generation ...)


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integrated osci.
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First yes sorry I always write XTAL while I mean a complete osc ... ;)
Why : It's not big and when you have a specific frequency for a screen / uart /
... generating
it with the PLL is sometimes annoying ...
 
 
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could be nice
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Yes, that what I meant. Don't put the resitors by default, just route them as if
they were
differential.


Sylvain

Re: SimmStick FPGA module
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small and
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necessary parts for a
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[..]
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FPGA board?

What you describe is essentially our Micromodule minus USB plus SRAM.
http://www.trenz-electronic.de/prod/proden18.htm

If you can live with our form factor we could collaborate on a version
with sram instead of usb.

For a cluster you can build a stack of these boards.

However I doubt that it makes sense to have boards that are so similar.

Kolja Sulimma




Re: SimmStick FPGA module

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[snip]
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Hi Kolja

the cheapest mm with XC3S200 is 114.84EUR add 5 EUR for the special
connectors, then you would need to always make a custom PCB with those 0.8mm
headers that adds up price. A simmstick can be plugged into solderless
breadboard or any 0.1 proto board and requires no special connectors, so its
a little bit of different in the use. If the fgpa-simmstick is sub 99USD
then, well there is room for everybody on this planet. :)

the micromodules are nice too of course !
Antti
PS I am little disappointed in the designer of the RetroBB for the trenz
micomodules, the delta sigma AD DA circuitry, there are some very important
caps and resistors missing... for sound applicaiton the input should be AC
coupled and comparator biased with vcc/2 and the output again should be AC
decoupled (well thats not so big mistake, but still it isnt nice to feed 2V
DC into headphones..) I think the circuitry is 1:1 copied from Xilinx
appnote without thinking. Sometimes thinking is good, even I consider that
as heavy physcial work (to be minized if possible). Sorry - I was really
terrified when I looked at the retroBB schematics!












Re: SimmStick FPGA module
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What is the use of the finger connector on Micromodule

Larry
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Re: SimmStick FPGA module
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HAHA its duplicate of your favorite interface JTAG!
Need to get piece of old floppy connector and saw it in pieces!

Antti



Re: SimmStick FPGA module
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thanks Antti !

Re: SimmStick FPGA module
Kolja,

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FPGA board?
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sram instead of usb.
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I think the Micromodule is a very nice design in it's version as it is (with
USB).
If you only add SRAM you still need a base board.

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Stacking is a nice idea. I also thought about stacking my Cyclone modules when
I've
too many of them laying around ;-)

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I think I will go with a Cyclone. So our two boards are not so similar.

Martin



Re: SimmStick FPGA module
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I personally thought that the simmstick standard has way too few pins (30)
for any serious work. That was the main reason for me to 'invent :-)' my own
bus standard. The latest incarnation is called 'H-Storm' and can be found
here: http://h-storm.tantos.homedns.org . I would suggest you to take a look.
It has more pins (72) and thus much more versatile than the simmstick. It's
already 3.3V powered so you can save the regulator. Even better: it has pins
for 2.5 and 1.8V power as well, so you might not need to deal with power at
all (not with the SpartanIII, the core power there is 1.2V).

I'm in the process of building an FPGA board to that bus myself, using a
spartan II-e device, but it shure would be nice to see someone else building
something along those lines.

Regards,
Andras Tantos



Re: SimmStick FPGA module
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Martin,

If you do decide to build a new proto board make sure you've got some form
of
securely mounting it. If you go with a SimmStick this is taken care of, but
I
had problems mounting your Cyclone JOP boards for prototyping. I didn't
have time to design/build a motherboard to plug the modules into to get
access
to the connectors so had to build a complicated jig to hold them securely.

Nial.

-------------------------------------------------------------
Nial Stewart Developments Ltd
FPGA and High Speed Digital Design
www.nialstewartdevelopments.co.uk



Re: SimmStick FPGA module
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He he. You do not need a real motherboard. Just single row connectors on
a breadboard and go (or the expensive version of this that I provide: Simpexp)

Martin



Re: SimmStick FPGA module
Another idea: What do you guys think about adding a slot for a SD Card [1].
They are cheap (about EUR 10,- for 128MB) and you get them up to 1GB!
However, the impact on the board is high: The connector is 'big' and
increases the board hight. A FPGA with a higher pin-count is needed. For
the solution without the SD Card a 100pin TQFP would fit, but now a 144pin
is needed - again a larger board.
And this adds again a few EUR/$. All these design decissions! You start with
a minimal core design and than start adding (unnecesssary) features again.

BTW: Has somebody inplemented an SD Card interface in an FPGA. It should
not be too hard [2]. The simplest solution would be the SPI bus.


[1] http://www.sdcard.org/sd_memorycard/index.html
[2] http://www.sandisk.com/pdf/oem/AppNoteMMC_SDv1.0.pdf

Martin
----------------------------------------------
JOP - a Java Processor core for FPGAs:
http://www.jopdesign.com /

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small and
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necessary parts for a
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build
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(similar
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available:
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DIL IC.
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processor
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and price.
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already available
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cluster with those
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FPGA board?
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Re: SimmStick FPGA module
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  You might want to consider two variants: one that is on the KISS path,
and is on the lower price knee, and just sufficent to operate a workable
JOP, and another that is more maximal, and more able to launch an
operating system as well.

  For package, I'd vote against pin-modules, as they are expensive
to make, have a pin count ceiling, and are easily damaged. The only
benefit is they can save a little time in first deployment.
  Better are the memory-card formats, as they have low cost and sturdy
connections, that can still be socket managed on 1 & 2 layer PCB, and
you can offer a socket-pcb for users starting from nothing.

  Besides the simmmstick itself, you should consider the SODIMM modules,
as seen in TINI :
  http://www.maxim-ic.com/products/tini/pdfs/TINI_GUIDE.pdf

  For "smart expansion", SD would be one option, but smaller and
more flexible might be USB-Drive ?. Not as cheap at the lowest node,
but universally portable - few PCs can R/W SD cards, but they can all
R/W a USB drive.
  Of course, that means the FPGA needs to be smarter :)

-jg


Re: SimmStick FPGA module
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I would be happy to go the KISS path, but I don't know how one can keep
a soft-cpu module simple to handle. You have too many options: You're
developing on two levels: the CPU inside the FPGA with peripheral components
and software for the CPU. During development on one of these areas different
ways for downloading the configuration/software fits best:

Simplest: Flash is configured with JOP waiting for a download of a Java program.
How do you donwload it? Via a serial interface - Then we need a serial interface.
Program the serial Flash with the Java program. Not very comfortable during
development - You have to use Quartus for the Flash programming, but you are
only interested in Java development.
Now you start changing JOP, e.g. do some FPGA development. Do you want to
program the Flash for every try or do you prefere to download the configuration
direct to the FPGA. Then we need a second ByteBlaster adapter (one for the Flash
and one for the Cyclone). Two pin heads need space and make it more complicate
to handle the board (not the KISS path).

Any ideas are highly welcome ;-)

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First ideas about the memory card format (still SIMM):
http://www.jopdesign.com/jopstick/index.jsp

One format is very small with a FPGA in TQFP100. There are just enough pins
for the SDRAM and the SimmStick bus. The second variant is larger with
a TQFP144 FPGA and a slot for a SD card.

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Yes, another option. However, is there a kind of 'standard' for this larger
modules.
Are there peripheral modules available for this form factor?

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Do you mean USB host? That's not so earsy. I would expect that the FPGA
(and the software) has to be too smart ;-)

Martin

PS.: Thanks for all suggestions from the usenet group! It's really fun to
discuss several
options during development of a board.



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