>Hello,
>
>I am considering to use Spartan 3 devices on our new board. Xilinx
>recommends XCF04S and XCF08P devices for configuration of a Spartan 3
>1000. Does anybody know other and cheaper configuration solutions for
>this FPGA?
>
>
Well, I'm always behind the curve on this stuff, but SST has some VERY
cheap flash serial memories. I'm using their 1 Mbit serial flash to config
a Spartan 2E chip. I had to make my own device programmer - basically
a single CMOS chip used as a level translator and a page of C code to
write/read it through a PC parallel port. And, I had to make up a minimal
circuit to send a read from address zero command into the chip. That takes
two SSOP packages on the board next to the FPGA. These chips can handle
up to 25 MHz in their ordinary mode, and up to 32 MHz if you tolerate a
one byte delay before output. Nice that Xilinx will waif for a byte of FF
before starting to interpret the config bitstream.
I think the 1 MBit chip is about $1.50 in small quantities, I get them
from Mouser.
They have larger, I don't remember how big they go.
Jon
Reply by rickman●September 27, 20062006-09-27
John_H wrote:
> "rickman" <gnuarm@gmail.com> wrote in message
> news:1159365978.100646.5140@i42g2000cwa.googlegroups.com...
> >
> > Do the S3e parts have the same issue with the overly stiff pullups that
> > the S3 parts have? I'm not sure if they are going to fix that in the
> > S3a parts or not.
>
> It was fixed, indeed. The pullups on the S3s were pretty stiff. Things are
> back toward expectations now with the S3E. I would expect the S3A to follow
> S3E's lead.
Fixed is a relative term. Worst case for the S3 is 1.4 kohms while the
Virtex 4 is 16.5 kohms. The S3E is between at 2.7 kohms, only about 2x
the S3 value and under a fifth of the V4 value. I can only assume that
there is some issue with the IO design in the Spartan series that makes
it hard to get a realisticly useful pullup value around 20 kohms like
the V4 and other Xilinx product use. I'm sure we will never know the
reason why.
Reply by John_H●September 27, 20062006-09-27
"rickman" <gnuarm@gmail.com> wrote in message
news:1159365978.100646.5140@i42g2000cwa.googlegroups.com...
>
> Do the S3e parts have the same issue with the overly stiff pullups that
> the S3 parts have? I'm not sure if they are going to fix that in the
> S3a parts or not.
It was fixed, indeed. The pullups on the S3s were pretty stiff. Things are
back toward expectations now with the S3E. I would expect the S3A to follow
S3E's lead.
Reply by Dolphin●September 27, 20062006-09-27
Hello,
It is correct that S3E is easier to configure using an SPI flash.
Because S3 devices have more IOs than S3E I have to use S3 for this
design.
Thanks for the info,
Dolphin
Reply by rickman●September 27, 20062006-09-27
Antti wrote:
> Falk Brunner schrieb:
>
> > Antti schrieb:
> >
> > > well the OP wanted S3 so thats not an option,
> >
> > Is it? Says who? I did not hear anything from the OP that prevents the
> > use of a S3E. There are many ways to skin a cat. ;-)
> >
> > Regardas
> > Falk
>
> OP wanted solution for S3, not for S3e
> for S3e the SPI flash is obvious, and I bet Xilinx FAE would have
> suggested it, so I must assume that the S3e wasnt an option
> and solution was really required for S3
>
> equally well I could say that solution is to use Cyclone or LatticeEC
> PFGA's
> as both support SPI loading and are comparable in size to Spartan-3, eg
> larger than larger device in Spartan3e
Do the S3e parts have the same issue with the overly stiff pullups that
the S3 parts have? I'm not sure if they are going to fix that in the
S3a parts or not.
Reply by Antti●September 27, 20062006-09-27
Gabor schrieb:
> Antti wrote:
> > Mike Harrison schrieb:
> >
> > > On 27 Sep 2006 02:03:55 -0700, "Antti" <Antti.Lukats@xilant.com> wrote:
> > >
> > > >Dolphin schrieb:
> > > >
> > > >> Hello,
> > > >>
> > > >> I am considering to use Spartan 3 devices on our new board. Xilinx
> > > >> recommends XCF04S and XCF08P devices for configuration of a Spartan 3
> > > >> 1000. Does anybody know other and cheaper configuration solutions for
> > > >> this FPGA?
> > > >>
> > > >> thanks and best regards,
> > > >> Dolphin
> > > >6 (or 8 pin) micro (costs 0.60 USD?) + SPI flash
> > > or 9536XL CPLD if you need more speed, not much more expensive
> >
> > the speed of the micro is ir-relevant, the FPGA generates the CCLK!
> > thats the beaty, cheapest smallest micro is enough, you only pushin
> > the read command, and let the FPGA todo the rest.
>
> Better make sure the SPI device has a continuous array read
> command. If you need to read per page, this technique won't
> work. By the way this sounds like you would need a little bit
> of extra logic to mux CCLK to the flash? Or were you supposing
> that the micro would push the command while the CCLK was
> free-running to the flash? Even at the startup CCLK speed that
> might require something a little faster than the cheapest smallest
> micro?
>
> >
> > the bitstream can embedded CCLK frequency to swithc to higher
> > configuration clock.
> >
> > XC9536 are cheap too, but even in smallest package they are rather
> > large compared
> > to tiny micros in QFN 11 or SOT package
> >
> > Antti
the micro holds PROG_B active so CCLK is tristated.
it takes a few clock cycles of the MCU to shift in the array read
and then all it has to be done is to make release the PROG_B
the FPGA does the rest at config speed programmed into the BIT file
Antti
Reply by Antti●September 27, 20062006-09-27
Falk Brunner schrieb:
> Antti schrieb:
>
> > well the OP wanted S3 so thats not an option,
>
> Is it? Says who? I did not hear anything from the OP that prevents the
> use of a S3E. There are many ways to skin a cat. ;-)
>
> Regardas
> Falk
OP wanted solution for S3, not for S3e
for S3e the SPI flash is obvious, and I bet Xilinx FAE would have
suggested it, so I must assume that the S3e wasnt an option
and solution was really required for S3
equally well I could say that solution is to use Cyclone or LatticeEC
PFGA's
as both support SPI loading and are comparable in size to Spartan-3, eg
larger than larger device in Spartan3e
Antti
Reply by Gabor●September 27, 20062006-09-27
Antti wrote:
> Mike Harrison schrieb:
>
> > On 27 Sep 2006 02:03:55 -0700, "Antti" <Antti.Lukats@xilant.com> wrote:
> >
> > >Dolphin schrieb:
> > >
> > >> Hello,
> > >>
> > >> I am considering to use Spartan 3 devices on our new board. Xilinx
> > >> recommends XCF04S and XCF08P devices for configuration of a Spartan 3
> > >> 1000. Does anybody know other and cheaper configuration solutions for
> > >> this FPGA?
> > >>
> > >> thanks and best regards,
> > >> Dolphin
> > >6 (or 8 pin) micro (costs 0.60 USD?) + SPI flash
> > or 9536XL CPLD if you need more speed, not much more expensive
>
> the speed of the micro is ir-relevant, the FPGA generates the CCLK!
> thats the beaty, cheapest smallest micro is enough, you only pushin
> the read command, and let the FPGA todo the rest.
Better make sure the SPI device has a continuous array read
command. If you need to read per page, this technique won't
work. By the way this sounds like you would need a little bit
of extra logic to mux CCLK to the flash? Or were you supposing
that the micro would push the command while the CCLK was
free-running to the flash? Even at the startup CCLK speed that
might require something a little faster than the cheapest smallest
micro?
>
> the bitstream can embedded CCLK frequency to swithc to higher
> configuration clock.
>
> XC9536 are cheap too, but even in smallest package they are rather
> large compared
> to tiny micros in QFN 11 or SOT package
>
> Antti
Reply by Falk Brunner●September 27, 20062006-09-27
Antti schrieb:
> well the OP wanted S3 so thats not an option,
Is it? Says who? I did not hear anything from the OP that prevents the
use of a S3E. There are many ways to skin a cat. ;-)
Regardas
Falk
Reply by Antti●September 27, 20062006-09-27
Falk Brunner schrieb:
> Mike Harrison schrieb:
> >>>I am considering to use Spartan 3 devices on our new board. Xilinx
>
> >>6 (or 8 pin) micro (costs 0.60 USD?) + SPI flash
> >
> > or 9536XL CPLD if you need more speed, not much more expensive
>
> Or simply use Spartan3E, which can directly interface to cheap SPI Flash?
>
> Regards
> Falk
well the OP wanted S3 so thats not an option,
sure S3E, S3A, V5 all support direct SPI config
Antti