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How to assign inferred logic to resource in Quartus

Hi,

I have a chain of registers to delay a certain wide signal 5 clocks. Quartus infers altshifttaps from this, which is fine because it saves me LEs.

Unfortunately the M512 where it places the inferred shift register causes a long delay to and from the rest of logic. I want to manually assign this inferred shift register to a specific M512 for timing purposes.

My question is two-fold:

1/ I tried assigned the affected registers to an M512 using Assignment Editor. Quartus ends up telling me this is an invalid location. This leads me to my next question:

2/ Does quartus look at location assignments before inferring shift regs, DSP blocks, etc? If not, this would explain #1 because LEs can obviously not be assigned to TriMatrix memory.

So is it possible to assign a location to something that I know will be inferred by Quartus to use a specialized resource? Or do I have to write my code to explicitely use the altshifttaps megafunction?

Reply to
cruzin
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Hi cruzin,

At present it is not possible to assign a location to something that will be inferred by Quartus to use a specialized resource. In this case the code should be written to explicitly use the altshifttaps function, so that you can assign a location assignment.

- Subroto Datta Altera Corp.

Reply to
Subroto Datta

Hi, you might want to try to write a .vqm netlist "Settings/Compiler Settings/Synthesis/Save a node-level netlist into a persistent source file (Verilog Quartus Mapping File)" after synthesis and use this netlist as your source file for place & route. All elements in the .vqm netlist will be persistent and it will be possible to do floorplanning based on this netlist. You can find more information on this flow in AN161.

- Wolfgang Loewer El Camino GmbH

"Subroto Datta" schrieb im Newsbeitrag news:g1KAb.39062$v% snipped-for-privacy@newssvr31.news.prodigy.com...

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Reply to
Wolfgang Loewer

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