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Altera_Forum's avatar
Altera_Forum
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9 years ago

Simulation error for mod 3 asynchronous in Quartus II

I have used Quartus II 14.1 (64-bit version).

I made a mod 3 asynchronous counter as Fig 1.

The functional simulation issues the error message as Fig 2.

And, the timing simulation result is weird.

I expect the result sequence is 00->01>10->(temporally 11)->00->01->........

But, the result is weird as Fig3.

Is this a simulator bug? Or, let me know what is a part of mistake.

Th higher version of Quartus II 14 is as the same.

Thanks,

Ed

3 Replies

  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    9 years ago

    Iteration limits occur when you have a logic loop that cause the system to oscillate in 0 time. It's probably something to do with the loop cause by the resets

  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    9 years ago

    I understand why the error has occurred.

    However as to the solution, I am unsure which parts must be altered or modified in order for the simulator to perform correctly like an actual circuit.

    Actual circuit is working correctly.