Running the 823 FADS board @ 72 MHZ

[Steve Rossi]

I've got a custom 823 board running on the bench at 80MHz 1:1 with PC100 SDRAM
with no problems but I had to re-program the UPM to do it. 50MHz is a sweet spot
(at least with my memories), but above 50MHz without re-programming the UPM
you're probably violating SDRAM timing somewhere.

Steve


Richard Hendricks wrote:

> I do not know of any *development* board that is running the faster
> speed CPU's in 1:1 mode.  I *do* know several customers are running
> their designs at 66 MHz 1:1.  There is also at least 1 customer I
> know of running 75 Mhz 1:1 without problems.  I wrote an application
> note describing how to do a high-speed SDRAM interface to the MPC823.
> Hint: PC66 will NOT work at 66 MHz.  PC100 in most cases won't even
> work at 75 MHz.  If you are interested in the app note, I recently
> published it on comp.sys.powerpc.tech
>
> Kirk Haderlie wrote:
> >
> > Are you aware of a development board that is running the faster speed CPU's?
> > We need the faster speed for our application.
> >
> > -----Original Message-----
> > From: Richard Hendricks [mailto:richard.hendricks at motorola.com]
> > Sent: Friday, June 09, 2000 9:44 AM
> > To: 'linuxppc-embedded at lists.linuxppc.org'
> > Subject: Re: Running the 823 FADS board @ 72 MHZ
> >
> > The FADS board are not designed to run at that speed.  Just for kicks,
> > I've tried seeing how fast I can go without problems.  At about 60 MHz
> > the SDRAM no longer works, and 68 MHz the DRAM starts not working.  This
> > is with the default 50 MHz tables.  With better tuning, it may be
> > possible
> > to go higher, but I doubt you could reach 72 MHz with the FADS.
> >
> > Kirk Haderlie wrote:
> > >
> > > We are trying to run the FADS board @ 72MHz and enjoying the infamous UPM
> > > tables.  Has anyone successfully run the FADS board at this speed and if
> > so
> > > would you be willing to share your UPM tables.  We  are trying to set them
> > > up for the SDRAM and 60-ns EDO DRAM.
> > >
> > > Kirk Haderlie
> > > kirk at vividimage.com
> > > Vivid Image Engineering
> > >
> >
> > --
> > MPC823 Applications Engineering Development
> > Get help from other MPC823 customers on the
> > comp.sys.powerpc.tech newsgroup!
> >
>
> --
> MPC823 Applications Engineering Development
> Get help from other MPC823 customers on the
> comp.sys.powerpc.tech newsgroup!
>

--
-------------------------------------------------------
Steven K. Rossi                     srossi at ccrl.mot.com
Staff Engineer
Multimedia Communications Research Laboratory
Motorola Labs
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