Re: [myhdl-list] Simulation control

[Juan P. C. <jp...@gm...>]

Henry,

How did you get away with running two simulations at the same time. MyHDL
uses global variables. I tried an approach with threads and as soon as I
start the 2nd simulation, the 1st one is messed up.

Thanks,

JP

On Tue, Apr 7, 2015 at 12:33 PM, Henry Gomersall <he...@ca...> wrote:

> On 07/04/15 15:56, Juan Pablo Caram wrote:
> > The link on "mixed mode" simulation is a proof of concept, but very
> > naive. I've put together a blog post discussing the difficulties that
> > one might find:
> >
> > http://caram.cl/developing-a-mixed-signal-simulator
> >
> > The link about interactive simulation is more along the lines of what
> > would be required, but using the function calls, not the interactive
> > console. I see it's using a debugger and that might make it extremely
> > slow. It would be ideal if this functionality was built into the
> > simulator. If I were to implement this functionality into the
> > simulator, any idea on where I should start? I haven't seen any
> > documentation about the operation of the simulator.
>
> I read your blog post, and I still don't see what the fundamental
> problem is.
>
> In your final example, your DAC and your ADC are going to have to be
> instantaneous samplers. It doesn't make any sense otherwise. What does
> it mean to have an event in between clock edges? MyHDL doesn't have any
> concept of signal timings. If the delay means something, you need to
> model that in the analogue side; from the perspective of the RTL model,
> there is some value at some clock edge.
>
> You can model different clock domains, you just have to go the whole hog
> and run each clock domain in a different process. You'll have to define
> your time resolution and have some kind of sync barrier on each
> resolution period (using some kind of meta clock).
>
> That is, on every resolution period, each process will sync with the
> other to keep the simulations timings the same.
>
> I've written a basic example with two clocks here:
> https://gist.github.com/hgomersall/6f9268023593ca5fd9d0
>
> I'm pretty sure the synchronisation function isn't doing what it should,
> but that just needs debugging. It might be easier to use Threading, but
> I'm not sure if MyHDL is safe for that (I don't know if there is any
> global shared state).
>
> Cheers,
> Henry
>
>
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