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Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
12 years ago

create different clocks at Test Bench

Hi ,

i create 2 different clocks at Test Bench :

1. clk_25M - clk_period = 1/25 MHz = 40 nsec

1. clk_100M - clk_period = 1/100 MHz = 10 nsec

At Model Sim I see correct wave of clk_25M .

The wave of clk_100M is wrong , the wave start at '0' and after 45 nsec rise to '1' and after 45 nsec fall to '0' for 5 nsec and repeate .

why is that ?

Test Bench file and waves pictures attached .

2 Replies

  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    12 years ago

    thats because the 100 MHZ clock wont change until after the 25MHz clock has changed. You need to put the two clocks in separate processes.