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System requirements for real time simulation using Proteus "ISIS"

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When simulating oscillator circuits using Proteus "ISIS" freqency changes are instantaneously visible on the scope. The frequency counter seems not to react. (if it does it takes quite some time at a CPU load of 99%).

My system is Intel Pentium 2.2GHz duo core and dual channel DDR-RAM 1GB.

What are the recommend CPU-speed and RAM space?



I think it varies depending on what you are simulating. I had a charlieplexing project with a strobbing led, and it my load was pretty high and proteus said it wasnt real time anymore.

But when I was simulating a buckboost circuit, it was real time and the load was less than 10%.

So i guess it depends on what you are doing.


The analog components of a spice simulation can take quiet a while to calculate, the behavioral models are very fast, so as tresca said, it depends on exactly what you're simulating.


Well-Known Member
I don't know ISIS, but generally "real time" means that a one second simulation would take one second of "real" time if it were running in hardware.

In this case, I would assume that the complexity of the simulation is such that it takes more time to simulate the code than it would in the actual hardware.

In other words, if you have an LED that should blink once per second, it will be slower than 1 second on the screen.

Ian Rogers

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does "simulation not running in real time" mean that the code will not execute if i burn the code in the uC??
Just because ISIS reports that the simulation isn't running in "real time" the stopwatch at the bottom gives you the real time... But to answer your question!! No. If you burn the μC with the software that works in the simulator...It should work.

I say should.... Other factors, that people forget, contribute to a working program... ISIS initialises variables to Zero.. This sometimes causes issues in the real world... also XTAL selection.. I have selected 20mHz so many times, If you don't set the FOSC to HS .... Works in ISIS.... not for real.
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