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Altera_Forum's avatar
Altera_Forum
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14 years ago

access to every address of SDRAM

I have a problem with reading and writing data on SDRAM, I need to access every address of SDRAM, this is my C code written for Nios: # include <stdio.h> # include <io.h> # define BASE_SDR...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
14 years ago

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Check that you are reading the correct value. In both your access methods, 6000 means that you are reading the 6000th *word* in the SDRAM, and words are defined as 32 bits, with both the IORD macro and the int pointer. So you are in fact reading addresses 0x805dc0 - 0x805dc3 (0x80000 + (6000 * 4))

Also remember that IORD bypasses the cache while the pointer access doesn't, so if this memory area is in the CPU's cache you can have different results between the two accesses.

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tanx for your answer, but is it possible to access address 6000, directly, i mean byte access not word? for example if i change the setting for sdram length width in sopc builder???