Thanks, Avishay, for the suggestion. I checked the unassigned pins and they are already set to tri-state input, so I looked for other possible problems.
I noticed something else that is probably causing my problem - now I need help to resolve it. In SOPC builder, I'm using the standard reference design but I have an error and a warning at the bottom message window of the GUI.
The error says "One or more components could not be located (ddr_sdram_component). Check
search path under
file->sopc builder setup... menu." I tried adding some directories like it said, but that doesn't seem to help. Next to the ddr_sdram component in the active components window, it says "(NOT INSTALLED)". Do I need to reinstall Quartus? How can I install just the missing component? (Where do I find it?)
The warning says "
nios development board, cyclone ii edition: SSRAM data byte-lanes are swapped. Refer to the Nios Development Board, Cyclone II Edition Reference Manual." Is this normal for this board? Do I need to correct this?
Dave