platform flash as storage?

[John Williams]

Hi folks,

We're looking for a high density serial flash part to hold microblaze
uclinux kernel and file system images. The problem with commodity
serial flash parts (SST, Nexflash etc) seems to be that they aren't
really available in high densities (~4 - 8 MB) yet. If someone can
correct me on this then please do!

Anyway I'm wondering if we could potentially use a Xilinx platform flash
part to hold both an fpga configuration and "random data". I know about
SystemACE, but we can't afford that many pins. For the same reason I
don't want to use regular parallel flash parts.

The idea is that the FPGA configures with a microblaze bitstream,
contained in the BRAM is a small bootloader that then sucks the kernel
and filesystem image (potentially several megabytes) out of serial
flash, copies it into external memory, then off it goes.

With the serial flash parts I've seen so far, we'd need at least 2 or 3
of them to fit everything we need (plus level translators since this has
to share an IO bank with 2.5V DDR, whereas serial flash devices
generally seem >2.8V).

It would be lovely if we could just put an 8MB xilinx platform flash
part on the board and use it to store both the configuration and our
software images.

Any thoughts?

Thanks,

John

 

[Antti Lukats]

John Williams <jwilliams@itee.uq.edu.au> wrote in message news:<bk841k$7hf$1@bunyip.cc.uq.edu.au>...

Hi folks,

We're looking for a high density serial flash part to hold microblaze
uclinux kernel and file system images. The problem with commodity
serial flash parts (SST, Nexflash etc) seems to be that they aren't
really available in high densities (~4 - 8 MB) yet. If someone can
correct me on this then please do!

sorry, I am waiting also for an FPGA with config loader from MMC card!
not avail.
systemace is nice.
you could do systemace-mmc controller with some small fpga not as nice
as systemace, but would work.
using platform flash for linux image storge would be real tricky at least.
might be theoreatically possible but you would need to use JTAG to get the
data asmuch as I understand., or add small logic that disables the configuration
of the FPGA and restart config, and 'fetch' the stuff 'appended' to bitstream
this would be fast download.


antti

 

[Lorenzo]

"John Williams" <jwilliams@itee.uq.edu.au> ha scritto nel messaggio
news:bk841k$7hf$1@bunyip.cc.uq.edu.au...

It would be lovely if we could just put an 8MB xilinx
platform flash
part on the board and use it to store both the
configuration and our
software images.

I think it's possible! You can store your custom code as it was a separate
"firmware", like if you have a second FPGA attached. Then the platform flash
will do the rest. Look at the app notes that show how to connect more than a
FPGA to a configuration flash/PROM.

--
Lorenzo

 

[jetmarc]

We're looking for a high density serial flash part to hold microblaze
uclinux kernel and file system images. The problem with commodity
serial flash parts (SST, Nexflash etc) seems to be that they aren't
really available in high densities (~4 - 8 MB) yet. If someone can
correct me on this then please do!

3 years ago I had no trouble purchasing the Atmel Serial Dataflash
AT45D161, which is 2 MBytes big. Certainly the higher densities became
available in the meantime.