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Altera_Forum
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21 years ago

Does Nios II custom instruction need clk_enable?

Hi all!!! http://forum.niosforum.com/work2/style_emoticons/<#EMO_DIR#>/rolleyes.gif I have a Nios II project with 3 custom instructions that export the signals to a shared user logic, out of...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
21 years ago

I reviewed the documentation for the custom instructions and you are right about the muxing (I&#39;m used to NIOS I custom instructions).

Since you are combinational, you don&#39;t need that enable. However, if you look at page 1-6 (pg 14) it states that if you do a combinational custom instruction you can not have an optional interface. Whether that applies to your design or not I&#39;m not sure (not sure why this is not possible for combinational logic, probably keep the timing high I&#39;m guessing).