I am looking for a good solution to the problem of providing a lot of memory to an ARM9 system, possibly an AT91RM9200 or perhaps a 9260. It will be a custom hardware design. I need to have at least 150MB of volatile storage. It could be flash, but it would need to tolerate 10-50K write cycles over the full data area. Data is coming from an ADC that will be streaming at slightly over 1MB/s.

As far as SDRAM, I see that Micron has the MT48LC32M16A2P (32Mx16) which is around $20. It would take three or more likely four of those. Cost might be acceptable if the part would be available for a few years. The bigger chips seem to all be a form of DDR, which I assume cannot be controlled by these processors. I could also consider a flash card, but know less about them. Perhaps a 512M or 1G card would have no trouble with the write lifetime requirement.

As far as USB, I need to implement a high speed, mass storage device. Previously I did this with a Cypress Cy68001. That did have the bandwith but development was very slow going. I might repeat it based on experience, but could not recommend it.

Any suggestions for approach on either of these challenges ?

Thanks,

AW
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Alex,

> I am looking for a good solution to the problem of providing a lot of
memory
> to an ARM9 system, possibly an AT91RM9200 or perhaps a 9260. It will be a
> custom hardware design. I need to have at least 150MB of volatile storage=
.

150MB volatile storage? Did you mean non-volatile?

> It could be flash, but it would need to tolerate 10-50K write cycles over
> the full data area. Data is coming from an ADC that will be streaming at
> slightly over 1MB/s.

1MB/second will be hard to stream to flash unless the multiple flash device=
s
are written in parallel. Because you're streaming to flash, NAND isn't
really a good option and NOR flash is expensive. If you're saying that
you're going to stream from an ADC to flash, then in 150K you can store
~0.1s of data.
=A0
> As far as SDRAM, I see that Micron has the MT48LC32M16A2P=A0 (32Mx16)
> which is around $20. It would take three or more likely four of those.

Ok, so 4x32Mx16 =3D 256MB.

> Cost=A0might be acceptable if the part would be available for=A0a few yea=
rs.
> The bigger chips seem to all be a form of=A0DDR, which I assume cannot be
> controlled by these processors. I could also consider a flash card, but
> know less about them. Perhaps a 512M or 1G card would have no trouble wit=
h
> the write=A0lifetime requirement.

There are no guarantees on sustained write performance using USB thumb
drives. However, there *are* guarantees on SDHC cards, a class 2 card woul=
d
do you OK. And they're CHEAP these days. You'd need an SDHC controller.
=A0
> As far as USB, I need to implement a high speed, mass storage device.
> Previously I did this with a Cypress Cy68001. That did have the bandwith
> but development was very slow going. I might repeat it based on
experience,
> but could not recommend it.
=A0
> Any suggestions for approach on either of these challenges ?

Choose an XScale like a few of our customers have, if you want to use DDR.
Of if you think you could get by with SDHC (no reason to believe otherwise,
might want to check write endurance, but SDHC cards have all that luscious
bad sector management built in and papered over). 926x don't support SDHC
IIRC, which is a shame. I might be wrong, I've read so many data sheets an=
d
some Atmel parts have had a featurectomy in the data sheet department
between revisions.
=20
--
Paul Curtis, Rowley Associates Ltd http://www.rowley.co.uk=20
CrossWorks for ARM, MSP430, AVR, MAXQ, and now Cortex-M3 processors

=20

=20


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Alex,

Have you looked at the 9263? The second external-memory bus might
come in handy in your application, since you could dedicate this to
your streaming-data channel. Or, you could decide to split the SDRAM
between the two buses, and use both in parallel.

The 9263-EK uses 2 MT48LC16M16A2TG SDRAM chips, which provide 64MB of
storage for about $10 (for the pair, Q1K) - would be twice the parts,
but about half the total cost.
--- In A...@yahoogroups.com, "Paul Curtis" wrote:
>
> Alex,
>
> > I am looking for a good solution to the problem of providing a lot of
> memory
> > to an ARM9 system, possibly an AT91RM9200 or perhaps a 9260. It
will be a
> > custom hardware design. I need to have at least 150MB of volatile
storage.
>
> 150MB volatile storage? Did you mean non-volatile?
>
> > It could be flash, but it would need to tolerate 10-50K write
cycles over
> > the full data area. Data is coming from an ADC that will be
streaming at
> > slightly over 1MB/s.
>
> 1MB/second will be hard to stream to flash unless the multiple flash
devices
> are written in parallel. Because you're streaming to flash, NAND isn't
> really a good option and NOR flash is expensive. If you're saying that
> you're going to stream from an ADC to flash, then in 150K you can store
> ~0.1s of data.
>
> > As far as SDRAM, I see that Micron has the MT48LC32M16A2P (32Mx16)
> > which is around $20. It would take three or more likely four of those.
>
> Ok, so 4x32Mx16 = 256MB.
>
> > Cost might be acceptable if the part would be available for a few
years.
> > The bigger chips seem to all be a form of DDR, which I assume
cannot be
> > controlled by these processors. I could also consider a flash
card, but
> > know less about them. Perhaps a 512M or 1G card would have no
trouble with
> > the write lifetime requirement.
>
> There are no guarantees on sustained write performance using USB thumb
> drives. However, there *are* guarantees on SDHC cards, a class 2
card would
> do you OK. And they're CHEAP these days. You'd need an SDHC
controller.
>
> > As far as USB, I need to implement a high speed, mass storage device.
> > Previously I did this with a Cypress Cy68001. That did have the
bandwith
> > but development was very slow going. I might repeat it based on
> experience,
> > but could not recommend it.
>
> > Any suggestions for approach on either of these challenges ?
>
> Choose an XScale like a few of our customers have, if you want to
use DDR.
> Of if you think you could get by with SDHC (no reason to believe
otherwise,
> might want to check write endurance, but SDHC cards have all that
luscious
> bad sector management built in and papered over). 926x don't
support SDHC
> IIRC, which is a shame. I might be wrong, I've read so many data
sheets and
> some Atmel parts have had a featurectomy in the data sheet department
> between revisions.
>
> --
> Paul Curtis, Rowley Associates Ltd http://www.rowley.co.uk
> CrossWorks for ARM, MSP430, AVR, MAXQ, and now Cortex-M3 processors
>



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Hi,

I briefly considered Xscale but they seem to be available in BGA only, and I
would not be able to fully leverage my familarity with Atmel's ARM family.
The 9263 has no pressing advantage in this application, and I am avoiding it
because it is too new and only comes in BGA. I am looking at high speed USB
as an IP core inside a FPGA. It does not look cost effective, but the data
is not all in.

Why not use an NXP high-speed USB transceiver? Something like the
ISP1582BS?

-- Paul.



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Thanks for the pointer to the SDHC cards, I barely knew anything about them and did not appreciate that they had guaranteed write performance. There are some annoying licensing issues for SD and SDHC, but perhaps that is acceptable. It turns out that the SD association recommends that cards of 2G or less be implemented as SD, and the new standard SD 2.00 includes the speed class rating. So there may be some cards coming that have these minimum speeds are are compatible with the 9260. It may also turn out that a 9200, 9260, or others in the family can write SDHC with appropriate software. As far as I could tell on a quick read, the main difference is that SDHC is addressed in blocks while SD as bytes.

It appears that a hybrid solution might be the least expensive of all. That would include enough RAM to buffer writes to even a very slow card, plus some cheap and readily available card like MMC. Perhaps a couple of the parts Twgbonehead suggested, MT48LC16M16A2TG (32M each), backed up by MMC or SD.

I briefly considered Xscale but they seem to be available in BGA only, and I would not be able to fully leverage my familarity with Atmel's ARM family. The 9263 has no pressing advantage in this application, and I am avoiding it because it is too new and only comes in BGA. I am looking at high speed USB as an IP core inside a FPGA. It does not look cost effective, but the data is not all in.

AW
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> Why not use an NXP high-speed USB transceiver? Something like the ISP1582BS?
>
> -- Paul.
That looks like a good choice. Thanks for suggesting it.

AW
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