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Design Languages >> Verilog-AMS >> 2 analog events causing "Process stopped by UNIX signal 6"
https://designers-guide.org/forum/YaBB.pl?num=1297701742

Message started by fabian on Feb 14^th, 2011, 8:42am

Title: 2 analog events causing "Process stopped by UNIX signal 6"
Post by fabian on Feb 14^th, 2011, 8:42am

Dear All,

I am hoping my problem is an interest for the forum. I have just been registered to our community and I wonder if I could have a tip on the following issue.

My code is as follow:
electrical in;

parameter real V_th=0.0;
parameter real ttol=10p;
parameter integer dir=1;
parameter integer flag_start=0;

real t1, v_meas;

analog begin

@(cross(V(in)-V_th,dir,ttol)) begin
t1=$abstime;
flag_start <= 1;
// $strobe("time: %g", t1);
end

@(timer(t1, 1u)) begin
if (flag_start==1) begin
v_meas = V(in);
$strobe("value: %e", v_meas);
end
end

This veriloga breaks the simulation with the message I have put in the subject. What I would like to implement is an event based on the outcome of an other. If I remove the condition "if", the two events are running without any issue but the second event is not waiting t1 value to be affected before to start.

Thanks for your feedback and remarks,
Fabian

Title: Re: 2 analog events causing "Process stopped by UNIX signal 6"
Post by Geoffrey_Coram on Feb 14^th, 2011, 10:21am

There's something odd about what you typed:

parameter integer flag_start=0;
...
flag_start <= 1;

What's this line doing? You can't change the value of a parameter from within the module.

Title: Re: 2 analog events causing "Process stopped by UNIX signal 6"
Post by fabian on Feb 14^th, 2011, 3:12pm

Hi Goeffrey,

This line is to change the flag value once the first even is true. The second event could then to effectively something as the if statement become true with the flag equal to 1.

So should I change my line to be

integer flag_start=0;

or should I initialize under initial bengin end

Regards,
Fabian

Title: Re: 2 analog events causing "Process stopped by UNIX signal 6"
Post by Geoffrey_Coram on Feb 15^th, 2011, 5:11am

I would do
integer flag_start;

and then in the analog block,

@(initial_step)
flag_start = 0;

I'm not sure that initialization as part of the declaration statement is supported by all simulators. Variables are initialized to zero automatically, per the LRM, but it's more clear to the reader if you show the initialization.

Title: Re: 2 analog events causing "Process stopped by UNIX signal 6"
Post by fabian on Feb 17^th, 2011, 4:01am

Hi Geoffrey,

Thanks is work.

My code looks like now
electrical in;

parameter real V_th=0.0;
parameter real ttol=10p;
parameter integer dir=1;
parameter integer flag_start=0;

real t1, v_meas;

analog begin

@(cross(V(in)-V_th,dir,ttol)) begin
flag_start = 1;
end

@(timer(0, 1u)) begin
if (flag_start==1) begin
v_meas = V(in);
end
end

What I do not understand it is why I have to start an event (@timer ) from 0us and do nothing until the flag is true instead of having this event starting from a time t1 as shown in my first code.

Thanks Fabian

Title: Re: 2 analog events causing "Process stopped by UNIX signal 6"
Post by Geoffrey_Coram on Feb 17^th, 2011, 6:57am

Did you try setting t1 to 1e6 (or something large) @(initial_step)?

Then the cross will set t1 to a value that will be hit.

Title: Re: 2 analog events causing "Process stopped by UNIX signal 6"
Post by fabian on Feb 17^th, 2011, 8:28am

Thanks it works.

I understand that I need to put t1=$abstime+10n instead of t1=$abstime; otherwise the event @timer does not start.

Thanks it closed the issue, I believe.