Stats

  • Locked Locked
  • Replies 3
  • Subscribers 66
  • Views 1571
  • Members are here 0
This discussion has been locked.
You can no longer post new replies to this discussion. If you have a question you can start a new discussion

How to filter X -> 0 or X -> 1 from signals for events

jaichandra

Hi all,

          I am having problem in filtering the changes from x->1 and x->0 on a singal which i use to generate events.

       For example,

            I have a simple port "a" of type in, which is connected to a DUT signal. DUT drives x on the signal "a" for some time initially

 (10ns)   and then drives the value 1. I declared an event as shown below. clk_r is a clock rising event. The first clk_r event is available

  well after signal "a" settles with the value 1.

      event a_e is rise(a$)@clk_r; 

   Because of the change from x->1 on the signal "a", i receive an event on a_e on the first clk_r event.

   Can anyone suggest me how i can filter this unwanted event.

  • MDK1234

    By default, ICC records transitions 1 -> 0 and 0 -> 1. To record transitions X -> 0 and

    X -> 1, use the set_toggle_includex command.

    Consider transition 0 -> X -> 1 -> 0 -> X -> 1.

    In the absence of the set_toggle_includex command,

    ■ The number of rise transitions is 0.

    ■ The number of fall transitions is 1 (1 -> 0).

    With this command,

    ■ The number of rise transitions is 2 (X -> 1 and X -> 1).

    ■ The number of fall transitions is 1 (1 -> 0).

  • jaichandra

    Hi MDK1234,

             Thanks for your reply. I created a work around for my issue by using the reset signal and ignoring the initial transitions from x->1 by checking if the reset is true.

       Thanks again for your reply.

     

     

  • hannes
    Hello Jaichandra,

    you can also use an event port and multi-value logic (MVL), which can distinguish between U, Z, X, 0 and 1:

    sd_rise : in event_port is instance;
       keep sd_rise.hdl_path() == “whatever you have for the other port”;
       keep sd_rise.edge() == MVL_0_TO_1;

    Regards,
    -hannes

Community Guidelines

The Cadence Design Communities support Cadence users and technologists interacting to exchange ideas, news, technical information, and best practices to solve problems and get the most from Cadence technology. The community is open to everyone, and to provide the most value, we require participants to follow our Community Guidelines that facilitate a quality exchange of ideas and information. By accessing, contributing, using or downloading any materials from the site, you agree to be bound by the full Community Guidelines.