Re: [Gnucap-devel] commands in verilog mode.

[Nathan Kohagen]

al davis said the following on 11/30/2007 04:13 PM:
> Verilog doesn't specify commands.  As far as I know, there are 
> no existing native Verilog-AMS simulators.  It looks like 
> gnucap is leading here.
>
> From what I see,in commercial simulators, Verilog-AMS is only 
> supported through something like a plugin mechanism.  The main 
> circuit seems to be spice format, or maybe a proprietary 
> format.

...

> comments?

Hi Al,

Related to adding support of Verilog-AMS, I think something that would 
be great is support for a digital simulator (such as Icarus Verilog) to 
control the gnucap analog kernel. When performing mixed-signal 
simulations there is usually large amounts of digital with one analog 
portion that you are targeting for the test and other analog blocks to 
support the test.

What I am invisioning is a replacement for Mentor Graphics ADvanceMS 
(Modelsim + Eldo) or Synopsys Discovery (VCS + Nanosim).

Support for Verilog-AMS could be accomplished as a preprocessor script 
to split into the digital (Icarus Verilog = Verilog-D) and analog 
(gnucap = Verilog-A/SPICE) kernels and link the whole mess together. 
Verilog-AMS is really a superset, so I think we should be take pieces 
that already good by themselves (Icarus and gnucap) and make them work 
together.

Just getting a Verilog-D inverter in Icarus Verilog driving a SPICE 
inverter in gnucap would be a good start.

Support for linking in SystemC and VHDL to digital simulations in Icarus 
Verilog (would probably need a name change then) would nice. VHDL-AMS 
could be handled as part of the preprocessor step like Verilog-AMS.
Adding Spectre support (as you have mentioned in recent postings) will 
make the analog part of the equation even more flexible!

An interesting paper is on creating a mixed signal environment with 
SystemC is:
"SEAMS - A SYSTEMC ENVIRONMENT WITH ANALOG AND MIXED-SIGNAL EXTENSIONS"
by H Aljunaid and T J Kazmierski in ISCAS 2004.

It describe the lock-step execution that needs to take place between the 
digital and analog kernels - rewinding the time-step, etc.

If gnucap was made to work with Icarus Verilog it would be also be 
controllable from SystemC and we would be effectively recreating SEAMS 
from the paper. I thought SEAMS was a parallel simulator that supported 
VHDL and later VHDL-AMS. Is this the same enviroment?

I would like to help create a mixed-signal environment.
Anyone else interested?

--Nathan