DDR SDRAM vs SSRAM

Hi, Wolfang.

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originally posted by wpaulus@Aug 17 2006, 07:03 AM

just a guess: the nios/f has data cache.

if another avalon master changes the value of your flag in memory, the nios/f processor doesn't notice, because it loads the value from the cache.

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Good point! I&#39;ve thought that declaring my on-chip memories instances as volatile, this problem couldn&#39;t happen. However, the problem is still deeper. I had already also tried to run the application under Nios/f processor without data cache (0Kb). The problem remained.

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originally posted by wpaulus@Aug 17 2006, 07:03 AM

if you load the values by using the &#39;ldwio&#39; opcode, you read the value directly from memory.

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I&#39;ve enjoyed your suggestion too much. Can you send me a simple example of how can I use that opcode. I don&#39;t know it yet. Or, maybe, the name of the header file where are declaring the routines I need to use. With this I suppose I can take more informations in Nios II Software Handbook.

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originally posted by wpaulus@Aug 17 2006, 07:03 AM

and depending on your optimization level, the value isn&#39;t read at all from memory, only a value in a processor register is checked. you can cirumvent this by adding &#39;volatile&#39; to your variable declaration.

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I&#39;ve checked my code again and, in fact, I used &#39;volatile&#39; in all the declaration of the 4 shared memories.

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originally posted by wpaulus@Aug 17 2006, 07:03 AM

also, isn&#39;t there a hardware mutex component that synchorinzes access to memory between different processors?

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Yes. Actually, each memory has a mutex protecting it.

This question remembers me another doubt. What, in fact, happens when a processor try to verify the value of a variable, like in (***)? I&#39;ve noticed, at least in my projects, that checking this before or after lock a mutex makes no difference. Is there no conflit among processor when trying to verify memory on this way?

Thank you to much, Wolfang. We had a good discussion here.

I&#39;ll be waiting new suggestions from Nios Community.

Regards,

Mendonça.