Re: Running the 823 FADS board @ 72 MHZ

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:

quoted

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@motorola.com]
Sent: Friday, June 09, 2000 9:44 AM
To: 'linuxppc-embedded@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:

quoted

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

quoted

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@vividimage.com
Vivid Image Engineering

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MPC823 Applications Engineering Development
Get help from other MPC823 customers on the
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MPC823 Applications Engineering Development
Get help from other MPC823 customers on the
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-------------------------------------------------------
Steven K. Rossi                     srossi@ccrl.mot.com
Staff Engineer
Multimedia Communications Research Laboratory
Motorola Labs
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