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Altera_Forum's avatar
Altera_Forum
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15 years ago

URGENT: Help needed for SRAM and on chip memory

Hello, I am using Altera DE2 Board with 512kb SRAM. But I cannot find the compatible SRAM in SOPC. The one on board is different from those in SOPC. Please help. I saw a lot of posts regarding this but none helps. :(

Besides, what is the maximum size for on chip memory? Even i set the size to 50Kb, quartus II cannot compile coz it said cant fit all RAM in design.

Please help me!

THANK YOU!

2 Replies

  • Altera_Forum's avatar
    Altera_Forum
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    To calculate On-chip memory,u can calculate like this,

    cyclone II has 105 m4k blocks for memory ( 4096bits+512 parity bits),so total accesable RAM bits will b (4608x105 ) =483,840 ram bits.

    With 8 bits ram interface,and without parity bits ,u can access 53,760 words,so this leads to 52.5 kb on chip memory.

    Since u set the 50 KB as an on chip memory so this settings will have no problms as long as 52.5 is max size but this means ur code requires more than 50 KB of memory

    So u can either reduce the programming length,or interface external memories like SDRAM or anything for getting more memory

    Hope this will help u a little.:)

    And i havenot used DE2 board so i don't know the SRAM issue in the SOPC builder but if SRAM is not "must" for u and if it is only the memory device for u to get some more memory bits than u can go for SDRAM.
  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor

    The Nios core will also use some memory blocks, especially if you have a cache enabled. So the actual maximum memory size will be lower.