The Designer's Guide Community Forum

The Designer's Guide Community Forum
https://designers-guide.org/forum/YaBB.pl
Design Languages >> Verilog-AMS >> unable to display verilogA waveform
https://designers-guide.org/forum/YaBB.pl?num=1276572652

Message started by casual on Jun 14^th, 2010, 8:30pm

Title: unable to display verilogA waveform
Post by casual on Jun 14^th, 2010, 8:30pm

when I simulate verilogA xor gate (copied from desinger-guide.org), Cadence CIW shows that "wave3 is not a waveform object tat can be displayed and will be turned OFF automatically"

There is no error on the code and I could simulate other verilogA code like latch.

xor verilogA code:

Code:

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

module axor (out, in1, in2);
//Copied from designers-guide.org

output out; voltage out;
input in1, in2; voltage in1, in2;

parameter real vh = 1; // output voltage in high state
parameter real vl = 0; // output voltage in low state
parameter real vth = (vh + vl)/2; // threshold voltage at inputs
parameter real td = 0 from [0:inf); // delay to start of output transition
parameter real tt = 0 from [0:inf); // transition time of output signals

analog begin
@(cross(V(in1) - vth) or cross(V(in2) - vth))
;

V(out) <+ transition( ((V(in1) > vth) ^ (V(in2) > vth)) ? vh : vl, td, tt );
end
endmodule

May I know why? I am new to verilogA.
I am using cadence 5141, mmsim61 spectreRF

Title: Re: unable to display verilogA waveform
Post by Geoffrey_Coram on Jun 15^th, 2010, 4:47am

I don't see "wave3" in the Verilog-A code. Perhaps you have a typo in your netlist?

Title: Re: unable to display verilogA waveform
Post by Marq Kole on Jun 15^th, 2010, 2:51pm

Indeed, as Geoffrey suggests the test bench for this Verilog-A model will give more information about the origins of the error message. The xor gate model is fine and would not give rise to the kind of error you indicated.

Marq

Title: Re: unable to display verilogA waveform
Post by casual on Jun 15^th, 2010, 10:02pm

thx for your reply.

it works after restarting the icfb..
but dont know why..

wave3 is the out of the xor in the test bench.