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Altera_Forum
Honored Contributor I
935 Views

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
0 Kudos
4 Replies
Altera_Forum
Honored Contributor I
37 Views

@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
Honored Contributor I
37 Views

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
Honored Contributor I
37 Views

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 ?

Altera_Forum
Honored Contributor I
37 Views

It would show up in the synthesis warnings.

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