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Altera_Forum's avatar
Altera_Forum
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8 years ago

Quartus removes logic functionality

Hello,

I started to use Quartus Prime 15.1.0 and DE0 Nano board. I want to try some functionality but Synthesis removes some blocks in the design and I do not know why.

Is there some possibility to see why some functionality is optimized out ?

Thank you for help.

Vaclav

4 Replies

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

    @Vaclav,

    Make sure the blocks outputs are used. By this I mean that the synthesizer will optimize away logic that it sees is not eventually providing a top-level output(pin).
  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    8 years ago

    Check the warnings and see what gets removed. Then ensure that:

    1. Clocks are connected

    2. Design is NOT stuck in reset

    3. Outputs are connected.

    You may need to work backwards to work out whats causing the logic removal.
  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    8 years ago

    Good point, thank you. I forgot to connect some signals on the top level. Is there any check in Quartus that some connections of the submodule are missing ?