Altera Quartus 4.0 - inconsistent simulation results

Oct 29, 2004 1 Replies

I have encountered a problem with Quartus 4.0 :



Component behaves different in simulations when placed in different projects. The behaviour change is quite severe, for example, the LPM_FIFO megafunction supposed to deactivate the "empty" signal when the data becomes valid on its output ports (Show-Ahead mode) and does so in one simulation. However exactly the same megafunction in a different project toggles "empty" signal long before the output becomes valid. I had similar problem with a flip-flop when it would not keep the signal it captured (no resets or anything) but when another flip-flop was connected in parallel to it in the design, it simulated fine.



I am at a point where I need to finalize my design, yet this prevents me from moving forward.



Does anyone know whats going on ?



Thnx.


You can see source code for lpm_fifo at:

formatting link

Talk to altera or write your own fifo.

-- Mike Treseler

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