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Altera_Forum's avatar
Altera_Forum
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14 years ago

Global reset promotion

Hello,

Is there a reason why high-fanout synchronous reset is not promoted to global signal network automatically (Quartus 11.1)?

"Global & Other Fast Signals" report shows only 3 global signals used.

My synchronous reset shows up first under "Non-global high fanout signals" with highest fanout among non-global signals.

This is for Stratix V device. I could not find in the documentation how many global signals it can have but I recall that Stratix II had about 16 of them so SV should not have less I guess.

Regards,

Michal

1 Reply

  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    14 years ago

    There are a lot of rules and the tools don't always do what you want. If you think it should be there, make a global assignment. It's always worth seeing what Quartus does and then deciding if another method is better. (You're definitely not running out...)

    One thought is timing. Getting onto a global is not necessarily very fast. Also, is it a full design? If you have only 3 globals, I'm guessing it's not, and hence the fan-out may not be large enough to really need a global. As I said, there are a lot of things Quartus uses in the decision process, and in the end there are often things that I would do differently.