URGENT: Help needed for SRAM and on chip memory

Altera_Forum · ‎03-06-2011

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!

Altera_Forum · ‎03-07-2011

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 · ‎03-07-2011

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.