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Last Post 29 May 2007 06:37 AM by  cbaron@nordson.com
System Speed
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cbaron@nordson.com
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Posts:22


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21 May 2007 03:00 PM
    Dear Sirs,
    We too are experiencing performance problems similar to one seen by Dawdyka and Vincent. Because of start-up issues we are using debug instead of Logic Loader. At this point we don’t know if the performance loss is due to slower ram settings from debug or some other problem. Could you send the SDRAM initialization code, or at least the register values? Also we are seeing 50Mhz at the processor clock input, however it looks more like a sinusoidal.
    lacroix_vin@yahoo.fr
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    24 May 2007 10:12 AM
    Hi,
    I made a few investigations:
    I executed a small program which number of instructions is well known (made of clr.l instructions for example) in different memories.
    The observed execution times are the following:
    - 9 ms in instruction cache (expected execution time for a 200 Mhz processor)
    - 114 ms in system SRAM
    - 156 ms in DDR SDRAM

    It seems there is a problem at the interface between the coldfire bus and the XL bus. You can find others people complaining about this on the Freescale forum but I don't find any confirmation or explaination from Freescale.

    Kind regards.

    Vincent.
    kurtl@logicpd.com
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    24 May 2007 10:17 AM
    Newuser,
    Once dbug or Logic Loader is running, you can use commands to read back the exact register settings for SDRAM or any other peripheral....

    -K
    cbaron@nordson.com
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    25 May 2007 06:26 AM
    Vincent,
    We talked with Freescale; The SDRAM controller came from a Power PC core and is designed to work in a 64 bit mode. The Cold Fire is a 32 bit bus, so a gasket was added to connect the two. NO consideration was given as to the performance loss that would result from this design. The 410 MIP figure from Freescale has nothing to do with a real application, it’s just a tricked out figure from marketing. The real performance is about 1 to 3 MIPS but you must make good use of cache. The MCF5329 uses what they call a “Cross Bar” bus, which they claim resolves the CPU to SDRAM delays. The new V5 core should also be better.
    lacroix_vin@yahoo.fr
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    29 May 2007 12:19 AM
    Thanks for your answer newuser,
    If the SDRAM controller is responsible for this slow system speed, one solution to use this chip with a real application is to connect an external RAM to the flex bus. Performances should be far better than in DDR SDRAM is that right ?
    cbaron@nordson.com
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    29 May 2007 06:37 AM
    Its the interface between the ColdFire and XL bus that causes the delays
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