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Altera_Forum
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12 years ago

Why i can't use CARRY&CARRY_SUM in QII11.1?

Hello Dears： I found i can use LCELL primitive in my project, but i can't use CARRY&CARRY_SUM primitive. My current QII version is 11.1+sp2. I remember i could use them in the old versio...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
12 years ago

Optimized away usually means your test design has no significant functionality that requires the respective resources.

I didn't yet use carry and carry_sum primitive, but I think your design has connections that can't be mapped to real hardware. As far as I understand, CIN can't be driven by regular logic output and COUT can't drive an regular logic input. CIN and COUT can be connected to each other or must be left unconnected.

Obligatory question with posts like this: What do you want to achieve?