Re: [myhdl-list] MyHDL Tristate Logic

[Alexander H. <ale...@gm...>]

Thank you for your replies.
I did now indeed switch to the manual way Jan described. Didn't know that
this was possible before. :-)

With this I managed to advance quite a bit with my I2C module but just ran
into a new problem. When converting the module to VHDL / Verilog I get a
warning
"** ToVHDLWarning: Output port is read internally: sda_oe" (sda_oe is the
output enable signal)
So far so good, but I nowhere do access the value of sda_oe internally.

The (quite lengthy) MyHDL and converted VHDL code can be find at pastebin.
Ctrl-F might help to find all sda_oe assignments.
MyHDL: http://pastebin.com/taVCdxR5
VHDL: http://pastebin.com/EPncdgba

I would be glad if you got any suggestions or tips.

Best,
Alex




2013/7/31 Christopher Felton <chr...@gm...>

> On 7/30/13 2:33 PM, Alexander Hungenberg wrote:
> > Hi all!
> >
> > I'm a new user of this very nice piece of software but unfortunately
> > stumbled upon some problem while implementing tri-state logic (of course
> > for an I2C module). Originally I wrote directly to Jan (thank you for
> > your reply!) and he pointed me to this mailing list.
> >
> > Regarding my problem, I am not sure whether it is a bug in MyHDL or my
> > fault, but the generated Verilog code looks wrong to me.
> >
> > MyHDL: http://pastebin.com/sQRnRPFL
> > Verilog: http://pastebin.com/qVzew9wg
> >
> > Especially the fact that tristate is declared as output and not inout as
> > well as the three assign lines make me kind of nervous. Do you have any
> > idea?
> >
> > Best,
> > Alex
> >
>
> This might be a bug, I haven't had time to identify
> a fix.
>
> I posted a tristate FAQ previously:
> http://article.gmane.org/gmane.comp.python.myhdl/2338/match=faq+tri+states
>
> I also copied the embedded code example here:
> https://gist.github.com/cfelton/6119313
>
> For this example, the VHDL creates the tristate and
> inout port correctly, whereas Verilog does not.
> Probably should create an issue on bitbucket.
>
> Regards,
> Chris Felton
>
>
>
>
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