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Analog Verification >> Analog Functional Verification >> VAMS clock period monitor- Help!
https://designers-guide.org/forum/YaBB.pl?num=1436854597

Message started by Rosh on Jul 13^th, 2015, 11:16pm

Title: VAMS clock period monitor- Help!
Post by Rosh on Jul 13^th, 2015, 11:16pm

I would like to measure the ON time of a clock pulse.

Code:

`include "disciplines.vams"

module measure_periods(in);

parameter real vdd_half=2.5;

input in;
voltage in;

real t0, t1;
analog begin

@(cross(V(in)-vdd_half,1)) //record time when clock rises beyond Vdd/2
t0=$abstime;

@(cross(V(in)-vdd_half,-1)) //record time when clock falls beyond Vdd/2
t1=$abstime;

t1=t1-t0;

end

endmodule

Will t1 record the ON time? Is this logic correct?

Title: Re: VAMS clock period monitor- Help!
Post by boe on Jul 14^th, 2015, 3:27am

Rosh,

Code:

t1=t1-t0;

will be executed every time step.
- B O E

Title: Re: VAMS clock period monitor- Help!
Post by Rosh on Jul 14^th, 2015, 3:29am

Hi BOE,

Thank you for the reply.

How will ensure that I print only one output instead of printing it continuously?

Thank you

Title: Re: VAMS clock period monitor- Help!
Post by boe on Jul 14^th, 2015, 8:17am

Hi Rosh,
I recommend you use
Code:

t1=$abstime;
t2=t1-t0;

as block at the falling edge event.
- B O E

Title: Re: VAMS clock period monitor- Help!
Post by Rosh on Jul 15^th, 2015, 2:15am

Thank you BOE