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Altera_Forum
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9 years ago

Methods of Halting/Stalling Nios II/f CPU, WAITREQUEST Scope and Access

Other than stopping the clock, is there a guaranteed way of halting or stalling the Nios II/f CPU without it losing its place (i.e., maintain PC, pipelines, and register values)? I see the W...
Altera_Forum's avatar
Altera_Forum
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9 years ago

Never used it, and there is almost zero information on it, but "debugreq" sounds promising:

https://www.altera.com/content/dam/altera-www/global/en_us/pdfs/literature/hb/nios2/n2cpu_nii5v1.pdf

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The "Include debugreq and debugack signals" debug signals setting provides the following functionality. When on, the Nios II processor includes debug request and acknowledge signals. These signals let another device temporarily suspend the Nios II processor for debug purposes.

The signals are exported to the top level of your Qsys system.

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But the more I think about it, I'd probably go for momentarily disabling the clock to the NIOS.