Quartus removes logic functionality

Altera_Forum · ‎09-26-2017

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

Altera_Forum · ‎09-26-2017

@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 · ‎09-26-2017

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 · ‎09-26-2017

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 · ‎09-26-2017

It would show up in the synthesis warnings.