Forum Discussion

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

pll_lock does not lock but the pll works

Hello, If i'm not wrong pll_lock works by positive logic, so i have this problem: My PLL Works but doesn't lock, anyone knows why? http://i46.tinypic.com/11lshsg.jpg As you can see CLO...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
13 years ago

--- Quote Start ---

IIRC the pll model in Modelsim waits a very long time before locking. Try to run your simulation over a longer period of time.

Are you sure your clock input is at the correct frequency?

--- Quote End ---

There can be seen a lot of transitions of the clock_27 signal.

Yes the clock_27 signal output of the PLL is correct even considering the input is X.