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Altera_Forum
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14 years ago

Will Nios II work with 16-bit SRAM?

I have been trying to get an external SRAM chip to work with Nios II for over two weeks with no success. I have tested the SRAM outside of SOPC Builder with a simple VHDL routine that writes to each...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
14 years ago

Good point on the SRAM speed grade. The one I am using is 45ns. This does not seem to be an issue as I have configured the timing - first in a custom component in SOPC Builder, and more recently in the Qsys Generic Tri-State Controller to slow down the interface to the external SRAM. This, by the way, is a very nice feature in Qsys. It takes a lot of the hassle out of interfacing to slow peripheral components.

Anyway, I finally discovered that the problem I was having in Eclipse of not being able to download an elf file was due to something else and not the SRAM.

A note to those trying to interface external SRAM, Qsys uses the address lines as though it were addressing bytes, not words. If your external SRAM is 16-bit, the LSB of the Qsys address is held low. The SRAM chip I'm using expects word addressing, so I did not connect the LSB (bit [0]) of the Qsys SRAM address.