DDR2 SRAM Stratix II questions

I posted this last week, but it has yet to show up on google groups, so
I fear my news server isn't as healthy as I would like.  So I apologize
if this gets double posted.

I'm involved with a project where we are trying to figure out if a
Stratix II will work for us.  Our big question mark right now is
memory.  We would really like to use a DDR2 SRAM (for reasons I don't
want to go into), but Mega-core doesn't support it.  We're not opposed
to building our own interface, but we're trying to understand the
possible reasons Altera doesn't support it.  We've been told that
basically there's just no demand, so that's why it's not there, but we
fear that's not the whole story.

First, we're very concerned about simultaneous switching outputs /
noise. I'm not familiar enough with Quartus to determine if there is an
SSO calculator (like there is in ISE).  We need to hang several memory
banks off a single part at 200 MHz, so this is a big concern.

Second, is the 1.8V HSTL driver in the Altera part capable of
supporting the bi-directional specs of a DDR2 SRAM at 200 MHz.  I'm
sure that this answer is buried somewhere in the Stratix docs, but so
far I have been unsuccessful in uncovering it - any help here?

Thanks,
Eric Amundsen
Special Purpose Processor Development Group
Mayo Foundation, Rochester MN 507-538-5457; Fax 507-284-9171

eric.amundsen@gmail.com wrote:

> We would really like to use a DDR2 SRAM (for reasons I don't
> want to go into), but Mega-core doesn't support it.

Anything wrong with this one?
http://www.altera.com/literature/ug/ug_ddr_sdram.pdf

> We're not opposed
> to building our own interface, but we're trying to understand the
> possible reasons Altera doesn't support it.  We've been told that
> basically there's just no demand, so that's why it's not there, but we
> fear that's not the whole story.

If time is an issue, buy standard interfaces.

   -- Mike Treseler

Mike Treseler wrote:
> eric.amundsen@gmail.com wrote:
>
> > We would really like to use a DDR2 SRAM (for reasons I don't
> > want to go into), but Mega-core doesn't support it.
>
> Anything wrong with this one?
> http://www.altera.com/literature/ug/ug_ddr_sdram.pdf

SRAM != SDRAM :-)

Tommy

Mike Treseler wrote:
> eric.amundsen@gmail.com wrote:
>
> > We would really like to use a DDR2 SRAM (for reasons I don't
> > want to go into), but Mega-core doesn't support it.
>
> Anything wrong with this one?
> http://www.altera.com/literature/ug/ug_ddr_sdram.pdf
>
> > We're not opposed
> > to building our own interface, but we're trying to understand the
> > possible reasons Altera doesn't support it.  We've been told that
> > basically there's just no demand, so that's why it's not there, but we
> > fear that's not the whole story.
>
> If time is an issue, buy standard interfaces.
>
>    -- Mike Treseler

The Stratix II supports DDR2 as an interface to the NIOS2 processor, as
indicated in the document pointed to by the link.  You didn't indicate
wether or not you were intending to use the NIOS2 or if you simply
wanted to implement a DDR2 controller in the Stratix for connection to
another processor.  I would recommend tracking down an Altera FAE or
seeing if there is a direct Altera application engineer in your area
that can pay you a visit.

As far as cores go, another place to look is at "open cores" (.org I
think it is). I believe they provide cores that you can download and
use free of charge.   I am not sure what their URL is though.

Noway2 wrote:
> Mike Treseler wrote:
> > eric.amundsen@gmail.com wrote:
> >
> > > We would really like to use a DDR2 SRAM (for reasons I don't
> > > want to go into), but Mega-core doesn't support it.
> >
> > Anything wrong with this one?
> > http://www.altera.com/literature/ug/ug_ddr_sdram.pdf
> >
> > > We're not opposed
> > > to building our own interface, but we're trying to understand the
> > > possible reasons Altera doesn't support it.  We've been told that
> > > basically there's just no demand, so that's why it's not there, but we
> > > fear that's not the whole story.
> >
> > If time is an issue, buy standard interfaces.
> >
> >    -- Mike Treseler
>
> The Stratix II supports DDR2 as an interface to the NIOS2 processor, as
> indicated in the document pointed to by the link.  You didn't indicate
> wether or not you were intending to use the NIOS2 or if you simply
> wanted to implement a DDR2 controller in the Stratix for connection to
> another processor.  I would recommend tracking down an Altera FAE or
> seeing if there is a direct Altera application engineer in your area
> that can pay you a visit.
>
> As far as cores go, another place to look is at "open cores" (.org I
> think it is). I believe they provide cores that you can download and
> use free of charge.   I am not sure what their URL is though.

First, this is not being used with a NIOS2 processor, or any other type
of processor.  Basically need memory hanging off of a data path for
data dependent storage/retrieval.

Second, we've been working with our FAE, but so far have basically been
told, with respect to our memory issues, that since DDR2 SRAM is so
rarely used we're pretty much on our own.  We're trying to get some
third party design services on board to help us out here, but those
wheels slowly.

I will poke around open cores.

Eric

"Tommy Thorn" <tommy.thorn@gmail.com> wrote in message 
news:1154368574.396239.245890@b28g2000cwb.googlegroups.com...
> Mike Treseler wrote:
>> eric.amundsen@gmail.com wrote:
>>
>> > We would really like to use a DDR2 SRAM (for reasons I don't
>> > want to go into), but Mega-core doesn't support it.
>>
>> Anything wrong with this one?
>> http://www.altera.com/literature/ug/ug_ddr_sdram.pdf
>
> SRAM != SDRAM :-)
>
Perhaps you should at least base your reply on the title of the document 
instead of the name of the link....or even better on more than just the 
title.

In any case, Altera's MegaCore (see link above) supports both DDR and DDR2 
memories.  I'm kind of missing why the original poster is not seeing this as 
well.

KJ 

KJ wrote:
> "Tommy Thorn" <tommy.thorn@gmail.com> wrote in message
> news:1154368574.396239.245890@b28g2000cwb.googlegroups.com...
> > Mike Treseler wrote:
> >> eric.amundsen@gmail.com wrote:
> >>
> >> > We would really like to use a DDR2 SRAM (for reasons I don't
> >> > want to go into), but Mega-core doesn't support it.
> >>
> >> Anything wrong with this one?
> >> http://www.altera.com/literature/ug/ug_ddr_sdram.pdf
> >
> > SRAM != SDRAM :-)
> >
> Perhaps you should at least base your reply on the title of the document
> instead of the name of the link....or even better on more than just the
> title.
>
> In any case, Altera's MegaCore (see link above) supports both DDR and DDR2
> memories.  I'm kind of missing why the original poster is not seeing this as
> well.

Yes but the link is for SDRAM (Synchronous Dynamic RAM) while the O.P.
asked about
SRAM (Static RAM)


   Sylvain

> Yes but the link is for SDRAM (Synchronous Dynamic RAM) while the O.P.
> asked about
> SRAM (Static RAM)
>
>
<snip from the original post>

We would really like to use a DDR2 SRAM (for reasons I don't
want to go into), but Mega-core doesn't support it

<end snip>

There is no such thing as DDR2 SRAM which implies that the original
post had a typo.  Given that the most likely explanation is that the
original poster meant to type 'DDR2 SDRAM' and not 'SRAM' as you have
surmised.

KJ

> There is no such thing as DDR2 SRAM which implies that the original
> post had a typo.

Look at this: http://www.necel.com/memory/en/products/sram/ddr-18m.html ;-)

Thomas 

Thomas Entner wrote:
> > There is no such thing as DDR2 SRAM which implies that the original
> > post had a typo.
>
> Look at this: http://www.necel.com/memory/en/products/sram/ddr-18m.html ;-)
>
> Thomas

I stand corrected.

Although I must admit that if all we're talking about is a synchronous
SRAM controller then that is almost trivial to put together for
oneself....to the point that I wouldn't let the lack of an Altera
MegaCore function deter me from using the part if that's what one has
in mind.  Take an hour or two and write the code.

KJ