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'[EE]: FLASH memory interfacing - really so complic'
2002\06\21@102128 by wzab

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Hi All,

I have to build a small FPGA based "memory controller", which should
use the FLASH memory contents to reconfigure some others FPGAs from time
to time. The whole thing will work in irradiated area, so there is a need
for memory errors detection and refreshing the memory contents, when it's
getting corrupted.
Anyway I need to implement a FPGA based FLASH memory controller, and when
I've checked the FLASH memory interface standards I got really upset.
Because of my special environment (radiation!) I prefer controllerless
FLASHes. I've found two standards: SmartMedia (description may be found
eg. in this datasheet:
samsungelectronics.com/semiconductors/Flash/SmartMedia/64M_Byte/K9S1208V0M/k9s1208v0m.pdf
) and CFI (description may be found there:
ftp://download.intel.com/design/flcomp/applnots/29220404.pdf )

Unfortunately both are so complicated, that I'm not sure if the suitable
controllers will fit in the reasonable FPGA...
Are there any simpler FLASH memory interface standards?

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2002\06\21@105635 by M. Adam Davis

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Does the flash have to be mobile?

You can use regular flash chips (dip, soic, etc) and it may be better
for you to do so.  They program/read in parallel and you can get them in
many sizes.

If you have to be able to move them (like the MMC, etc) then you can
easily build your own cartridge with radiation hardening on the outside.
You can even get radiation hardened chips from some manufacturers (made
for space applications).

Digikey has some, I'm sure you can get them from RS or your local
electronics supplier.

-Adam

Wojciech Zabolotny wrote:

{Quote hidden}

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2002\06\21@105902 by Tal Dayan

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Yes,

IDE   http://www.m-sys.com/content/products/FFDfamilyPage.asp

TFFS
http://www.m-sys.com/content/products/product.asp?PID=2&FILE=doc2k&FAM=doc

and

USB  http://www.diskonkey.com/

All from the same company, M-Systems .

Tal

> {Original Message removed}

2002\06\21@111423 by M. Adam Davis

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He is looking for controllerless flash memory - the controller adds one
more point of failure in a radiation intense environment.

-Adam

Tal Dayan wrote:

{Quote hidden}

>>{Original Message removed}

2002\06\21@112828 by Alan B. Pearce

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>The whole thing will work in irradiated area, so there is a need
>for memory errors detection and refreshing the memory contents,
>when it's getting corrupted

What sort of radiation level?

Instruments on space craft these days routinely use flash memory for the on
board processors, and these can be suitably shielded to 100k and 300k Rad
levels. This shielding includes the aluminium box, and if necessary a
tantalum metal piece is glued onto the most sensitive chips.

It may be that you will need to talk to chip manufacturers to get the
specifics of what level and type of radiation they can withstand.
Essentially if a chip is using 0.25 micron or finer geometry it will be
inherently radiation proof to a significant level.

If you are outside the USA, and attempting to get chips that are stated as
radiation proof then you will have to complete an End User Agrrement so the
US Government can sign off exporting items they consider of strategic
importance for export. No chip manufacturer will risk sending you anything
without this being signed off by appropriate folks in the US State
Department.

If you have access to anyone in a Space Science department at a University
or elsewhere doing hardware then it is probably worth getting in touch with
them. People involved with Physics Resaearch may also be able to help you,
where they have built detectors for particle accelerators and the like, but
I get the feeling that this is the area you are dealing with.

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2002\06\21@113252 by Alan B. Pearce

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>He is looking for controllerless flash memory - the
>controller adds one more point of failure in a
>radiation intense environment.

Maybe, see my previous post on this topic and consider the implications of
using controller chips that happen to have fine device geometry.

I suspect that the problems of radiation erasing the flash device is
probably an order of magnitude higher than problems with the controller, but
have no figures to back this up.

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2002\06\21@122034 by Brendan Moran

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----- Original Message -----
From: "M. Adam Davis" <adampicspamKILLspamUBASICS.COM>
To: <.....PICLISTKILLspamspam.....MITVMA.MIT.EDU>
Sent: Friday, June 21, 2002 7:54 AM
Subject: Re: [EE]: FLASH memory interfacing - really so complicated?
>
> Digikey has some, I'm sure you can get them from RS or your local
> electronics supplier.

RS.  You mean RadioShack?  In Canada, or at least in B.C. RadioShack is the
electronics store that used to be.  If you want components, you *can't* go
to RadioShack.  They won't have them.  I know they've dropped most of their
component inventory in all the stores in the Greater Vancouver, but I
suspect that it extends throughout B.C.

--Brendan

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2002\06\21@123320 by M. Adam Davis

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There is a large catalog order company called RS electronics which
appears to be europe centric.  I've heard good things about them.

I was not speaking of Radio Shack, although they have a decent selection
of components in my area (I have two stores within 3 miles of me, one in
walking distance).  This could be because of the University of Michigan
also in the area, as well as Eastern Michigan University and Washtenaw
Community College - all of whom have electronics programs of varying
usefulness.

Expensive, and not a good selection, but nice to have for the occasional
I-Need-It-Now requisition.

The email address of the original post seems to indicate a person
outside the US, which is why I suggested RS Electronics.

-Adam

Brendan Moran wrote:

>{Original Message removed}

2002\06\21@124647 by Alan B. Pearce

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>RS Electronics.

I believe their proper name is RS Components.

Useful throughout Europe and Australasia. Possibly also South Africa, but no
certain knowledge of this.

Website at rshttp://www.com/ fro the UK, but I prefer their catalogue CD.

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2002\06\21@125056 by Peter L. Peres

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Do you have to use removable flash ? If not get a standard pin-out 16M or
larger flash and just use it. Or design your own cartridge with several of
these.

Peter

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2002\06\21@151358 by Wojciech Zabolotny

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On Fri, Jun 21, 2002 at 04:31:54PM +0100, Alan B. Pearce wrote:
> >He is looking for controllerless flash memory - the
> >controller adds one more point of failure in a
> >radiation intense environment.
>

Exactly.

> I suspect that the problems of radiation erasing the flash device is
> probably an order of magnitude higher than problems with the controller, but
> have no figures to back this up.

The radiation tests show, that FLASH memories are the best devices to store
information in such environment (the longest expected time to single bit
corruption).
The controller has to be designed in a special way to eliminate at least the
SEU (Single Event Upset) effect. I think the controllers embedded in common
FLASH cards are not built that way :-(.
I can design my own controller to assure the appropriate level of "radiation
hardness", but I have to detect/correct memory errors.

Another solution may be a RAM chip with a controller performing cyclical
read/error correction/write operations. (The expected time between
single bit corruptions for typical RAM will be 10-100s for that
radiation level).

BTW. The built in ECC systems found in many modern memories are rather
obstacle to get the proper results...

On Fri, Jun 21, 2002 at 04:28:40PM +0100, Alan B. Pearce wrote:

> What sort of radiation level?
>
> Instruments on space craft these days routinely use flash memory for the on
> board processors, and these can be suitably shielded to 100k and 300k Rad
> levels. This shielding includes the aluminium box, and if necessary a
> tantalum metal piece is glued onto the most sensitive chips.

There is no way/no place to assure the enough shielding. The whole thing
will work in a detector very near to the bunch crossing point of an
accelerator.

> It may be that you will need to talk to chip manufacturers to get the
> specifics of what level and type of radiation they can withstand.

AFAIK there was no way to obtain that data from manufacturers so we had
to collect data about the radiation hardness performing our own tests...
(see eg. lhcb-elec.web.cern.ch/lhcb-elec/html/radiation_hardness.htm
or www-ekp.physik.uni-karlsruhe.de/~dierlamm/irradiation_center
or www.google.com/search?q=cache:LS5A3lKzPF8C:www-hep.fzu.cz/pixpage/IRR/RHAWG1.pdf
)

> Essentially if a chip is using 0.25 micron or finer geometry it will be
> inherently radiation proof to a significant level.

The design will be implemented in a few thousands of boards, so it must
be REALLY price optimized.

> People involved with Physics Resaearch may also be able to help you,
> where they have built detectors for particle accelerators and the like, but
> I get the feeling that this is the area you are dealing with.

Exactly, this is the case.

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2002\06\24@043534 by Alan B. Pearce

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>The design will be implemented in a few thousands
>of boards, so it must be REALLY price optimized.

Do not forget to include the cost of doing the radiation characterisation in
the price optimisation :)

It may be that you are better to do the controller design in VHDL and put it
in an FPGA with suitable fine geometry internal structures to get the
radiation hardness (see my comment about 0.25 micron geometries). This
should certainly be a price competitive way to go if needing to build
several thousand units.

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2002\06\28@170105 by wzab

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On Mon, Jun 24, 2002 at 09:34:39AM +0100, Alan B. Pearce wrote:
> >The design will be implemented in a few thousands
> >of boards, so it must be REALLY price optimized.
>
> Do not forget to include the cost of doing the radiation characterisation in
> the price optimisation :)
>
> It may be that you are better to do the controller design in VHDL and put it
> in an FPGA with suitable fine geometry internal structures to get the
> radiation hardness (see my comment about 0.25 micron geometries). This
> should certainly be a price competitive way to go if needing to build
> several thousand units.

The controller will be implemented in VHDL (or Verilog) with additional
circuits for detection of SEU (single event upset) errors.
However the controller itself shouldn't loose its configuration.
Therefore I'd like to use antifuse based EPLD. AFAIK it is vulnerable
to SEU, but does not loose its configuration like RAM, FLASH or EEPROM
configurable FPGAs do.
The 0.25 um technology probably may decrease the probability of SEU,
(but are there any antifuse based EPLDs in that technology available?)
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'[EE]: FLASH memory interfacing - really so complic'
2002\07\01@041336 by Alan B. Pearce
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>The controller will be implemented in VHDL (or Verilog)
>with additional circuits for detection of SEU (single
>event upset) errors. However the controller itself
>shouldn't loose its configuration. Therefore I'd like to
>use antifuse based EPLD. AFAIK it is vulnerable to SEU,
>but does not loose its configuration like RAM, FLASH or
>EEPROM configurable FPGAs do. The 0.25 um technology
>probably may decrease the probability of SEU, (but are
>there any antifuse based EPLDs in that technology available?)

Well about this time last year I finished up on a project which is part of
an instrument to be launched into space. We used Actel 1080 series FPGA's in
it, and I know another portion of the same instrument used the 12xx larger
brother of the same chip. These devices are described as Rad Hard, and as
far as I am aware are SEU free.

While the flight hardware used RH MIL Spec chips for which we had to get a
licence as I described previously, you should be able to get the commercial
versions without trouble.

My understanding is that the finer geometry leasons the SEU risk, as there
is no longer a large enough geometry area for the particle charge to reside
and upset things, but then I am not a semiconductor design person, so could
be wrong here.

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