AMS simulation

Hello everyone,
I am facing a problem with the Verilog-AMS model simulation. I am
using the Cadence LDV-4.1 toolset and trying to simulate a simple
resistor model with an analog control file (the test bench).
The first two steps (compilation and elaboration) are working fine
and I am not getting any errors. However when I simulate using ncsim,
I get an error. I am using using the resistor model that is in the
ncvlog manual just for checking whether the tool is working or not. I
am listing all the messages that I get when I execute the commands.
The hdl.var and cds.lib files are also included.

NCVLOG:

~/verilog11-9> ncvlog -ams -messages trial.vams
ncvlog: 04.10-s022: (c) Copyright 1995-2003 Cadence Design
Systems, Inc.
file: trial.vams
module worklib.restor:module
errors: 0, warnings: 0



NCELAB:

~/verilog11-9> ncelab -messages worklib.restor:module
ncelab: 04.10-s022: (c) Copyright 1995-2003 Cadence Design
Systems, Inc.
Elaborating the design hierarchy:
Discipline resolution Pass...
Building instance overlay tables: ....................
Done
Loading native compiled code: ....................
Done
Building instance specific data structures.
Design hierarchy summary:
Instances Unique
Modules: 1 1
Interconnect: 2 -
Writing initial simulation snapshot:
worklib.restor:module
Elaborating analog portion of the design hierarchy:
libsyracuse: @(#)$CDS: libsyracuse version
12/17/2003 03:11 (ncss21) $(sub-version 1217 )



NCSIM:

~/verilog11-9> ncsim -amslic -messages -analogcontrol trial.scs
worklib.restor:module
ncsim: 04.10-s022: (c) Copyright 1995-2003 Cadence Design
Systems, Inc.
Loading snapshot worklib.restor:module .................... Done
Starting analog simulation engine...
libpalermo: @(#)$CDS: libpalermo version
12/17/2003 03:11 (ncss21) $(sub-version 1217 )

Analog Kernel using -ANALOGCONTROL trial.scs.

Error found by spectre during circuit read-in.
trial.scs: RESTOR is an instance of an undefined model
restor.

spectre terminated prematurely due to fatal error.
ncsim: *E,RNAERR: Simulation is complete, analog initialization
error.


CDS.LIB:

INCLUDE /opt/CAD/Cadence/LDV-4.1/tools/inca/files/cds.lib
DEFINE worklib ./worklib


HDL.VAR:

SOFTINCLUDE $LDV-4.1/tools/inca/files/hdl.var
define ncuse5x
define cdslib ./cds.lib
DEFINE LIB_MAP (./ => worklib)
DEFINE worklib ./worklib


# Define view mapping.
# Files with .vb extension are compiled into view beh
# Files with .vr extension are compiled into view rtl
# Files with .vg extension are compiled into view gates
# Files with .vams extension are compiled into view module
DEFINE VIEW_MAP (.vb => beh, \
..vr => rtl, \
..vg => gates, \
..vams => module)


I am clueless as to why the simulator is not able to locate the
restor model. I would greatly appreciate if someone could suggest me a
solution to this problem.

Thanks and regards,
Guneet

 

Please show us trial.vams and trial.scs; that will help us to explain the
problem. Trying to debug from the error messages alone is rather hard!

Thanks,

Andrew.

 

Mr Beckett,
I'm sorry, I forgot to include the model file and the control file
along with the listing.
Here they are:

trial.vams :

`include "disciplines.vams"
`include "constants.h"

module restor(p,n);
inout p,n;
electrical p,n;
parameter real r=0;

analog
V(p,n) <+ r*I(p,n);

endmodule


trial.scs:

simulator lang=spectre
global gnd

ahdl_include "trial.vams"

ir in gnd isource dc=1m
r1 in gnd restor r=1K

saveNodes options save=allpub
paramSwp dc start=1 stop=1001 param=r dev=r1


I would be grateful if you could help me out on this.

Thanks,
Guneet

 

Hi Guneet,

What you're doing doesn't make sense. Your control file for AMS is actually a
spectre netlist, whereas it should only contain the options and analyses (just
tran in practice).

You can do the simulation just by running spectre:

spectre trial.scs

with what you have. If you want to use AMS Designer, you'd need to have the
top level as a Verilog-AMS netlist. For example:

`include "disciplines.vams"
module top;
electrical in,gnd;
isource #(.dc(1m)) ir (in, gnd);
restor #(.r(1K)) r1 (in, gnd);
endmodule

Then compile this:

ncvlog -ams top.vams

as well as the trial.vams you already compiled.

Then have a control file such as this:

//
tran tran stop=100n

And run:

ncsim -ams -analogcontrol control.scs worklib.top:module

You can then use the UI:

ncsim -ams +gui -analogcontrol control.scs worklib.top:module

etc as well.

In this case there's no digital, and so you might as well just use spectre, but
I'm assuming you're going to develop it into something bigger.

Regards,

Andrew.

 

Mr. Beckett,
Thanks a lot for the help. The simulation worked this time. I am
indeed very grateful to you.
Thanks and regards,
Guneet