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Altera_Forum's avatar
Altera_Forum
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21 years ago

nios II implementation problem

Respected members, I have some doubts on Nios II processors. I am requesting the forum members to clarify my doubt. When designing NiosII processor system using SOPC builder, there is a on...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
21 years ago

Yes, most on-chip ROMs are writable when the processor is in debug mode.

To explain - when Quartus instantiates a ROM it's normally using M4K blocks but not connecting the write enable. SOPC builder ROMs have the write enable connected, but gated by a signal which the processor outputs when in debug mode.

This is safe, as when the processor is in debug mode its running a debug monitor supplied by nios2-gdb-server. This monitor can be used to write code into the ROMs if you change it from within the IDE to save you from having to download a new SOF.

Next time you synthesise the design Quartus will pick up the most recent output from the IDE and put that into your SOF file.