Logic simulation: Difference between revisions

Revision as of 02:40, 17 August 2010

Revision as of 06:29, 12 September 2010

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In cycle simulation, it is not possible to specify delays. A cycle-accurate model is used, and every gate is evaluated in every cycle. Cycle simulation therefore runs at a constant speed, regardless of activity in the model. Optimized implementations may make take advantage of low model activity to speed up simulation by skipping evaluation of gates whose inputs didn't change.

While event simulation can provide some feedback regarding signal timing, it is not a replacement for [[static timing analysis]]. In comparison to event simulation, cycle simulation tends to be faster, to scale better, and to be better suited for hardware acceleration / emulation. However, chip design trends point to event simulation gaining relative performance due to activity factor reduction in the circuit (due to techniques such as [[clock gating]] and [[power gating]], which are becoming much more commonly used in an effort to reduce power dissipation). In these cases, since event simulation only simulates necessary events, performance may no longer be a disadvantage over cycle simulation. Event simulation also has the advantage of greater flexibility, handling design features difficult to handle with cycle simulation, such as [[asynchronous logic]] and incommensurate clocks. Due to these considerations, almost all commercial logic simulators have an event based capability, even if they primarily rely on cycle based techniques.

== Summary ==

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* [[List of Verilog simulators]]

* [[Functional verification]]

== References ==

{{reflist}}

== External links ==

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* [http://www.logiccircuit.org/ LogicCircuit – is educational software for designing and simulating digital logic circuits.]

* [http://www.esng.dibe.unige.it/deeds/Index.htm Deeds - free educational suite for digital logic circuit simulation and design, including finite state machines (FSM) and microprocessors simulation and design facilities.]

== References ==

{{reflist}}

[[Category:Electronic circuit verification]]