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Altera_Forum's avatar
Altera_Forum
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16 years ago

Some issues about functional simulation

Hi,all when i do the functional simulation for my projection,i find that some of the initial values of my signals are not cleared to "0".how can i do to clear them? thanks.
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
16 years ago

I don't know, if you are talking about Quartus or ModelSim functional simulation? At least with ModelSim, uninitialized signals show a value of 'U'. That means, e.g. a frequency dividing counter can't work, unless you initialize it.

In VHDL, setting an initial value with the signal definition is the most simple method, e.g. 

signal counter : unsigned := (others => '0');

Also an explicite reset initialization works of course.