sdram write fails for last 1K locations

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originally posted by shilpa v.prabhu@Mar 23 2007, 04:50 AM

hi all,

i have used sdram controller provided by sopc builder(custom). the sdram part i am using is is42s16400d. it is 8mb sdram. in the system library properties i have given .text, .rodata, .rwdata, heap and stack as sdram. i am not able to read or write into first few locations of sdram, as this part of memory is used to store the code.this i can understand.

but i am also not able to write into last few locations(2k) of sdram. when i continuously write into these locations using a for loop, the data which i get after reading is wrong. when i do a write to single location and read back, then i am getting proper data. the same c code works for all other locations but not for last 2k locations. i am not able to understand this behaviour. i have tried this on simulation and on board. in both the cases continous write to last 2k locations is failing and if i perform write and read individually then it is passing.

please help me in debugging this issue. is this a timing issue? if so why is it failing only for last 2k locations?

thank you...

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Hi,

I&#39;m using a similar SDRAM (IS42S16100C1), which has 16MBit. Somehow I kept in mind that .text, .rodata and .rwdata is stored at the beginning of the memory and heap and stack at the end of memory.

Sorry, but I really can&#39;t remember where I read that and please, somebody correct me if I&#39;m wrong.

What I do is, I store .text, .rodata and .rwdata in the SDRAM and heap and stack in onchip_memory. I&#39;m not totally done with testing that, but until now, this seems to work. Maybe try to declare 2K (or 4K) as onchip memory and use it for heap and stack.