On May 28, 7:55 am, KJ <kkjenni...@[EMAIL PROTECTED]
> wrote:
> On May 27, 4:37 pm, rickman <gnu...@[EMAIL PROTECTED]
> wrote:
>
> > I was considering what it will take to implement a bi-directional
> > switch in VHDL and found this by Peter Ashenden. The method is pretty
> > much what I had thought of,
>
> > I haven't simulated this. Any idea if I am off base here?
>
> Another example you might want to look at is Ben Cohen's zero ohm
> resistor model.
>
> http://www.google.com/search?hl=en&rlz=1G1GGLQ_ENUS278&q=%22Ben+Cohen...
>
> KJ
I may have replied too soon. I'm not sure his resistor even works.
If A and B have different values, the model will drive each bus with a
'Z' initially. Then after a delta delay each bus will be driven with
the state of the other. This will put an 'X' on each bus. This
triggers the process again and the model drives a 'Z' again. Now the
value of the bus returns to the values driven by the A and B drivers
and the process repeats. It looks to me like it will infinite loop
oscillating, just advancing delta times and never advance in real
time.
Again, a simulation is worth a thousand code reviews.
Rick
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