Is On-Chip Memory Size Configurable on the NIOS II?

Hi Neil!

First of all, thank you for reaching us. I'm Eliath Guzman.

unfortunately, there is not a way to change the memory size by software.

This is because when you are creating the project and defining the parameter on Platform Designer before going to Nios II, you must indicate the size of the memory you need. Each device has a maximum possible size, it depends on the number of regions available for this proposal in the FPGA.

So... to do this follow the next steps:

1. From the Qsys library pick list, look inside the Memories and Memory Controllers --> On-Chip folder and select On-Chip Memory ( RAM or ROM) then, click Add.
2. Configure the memory :

• Set the memory width to ... ( could be 4-8-16-32 bits, depends on your requirements)
  • Set the Total Memory Size to .... the size you need, in this case, you mentioned that a 256Kb is needed.
  • Set the Dual-Port Access to Enabled
  • Click Finish

You also could consult this document.

If you need more information about how On-chip memory works, consult this link.

Please, let me know if there's something else I can do for you or if you have any questions about the answer above.

Thanks,

-Eliath