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Altera_Forum
Honored Contributor
Honored Contributorcan cyclone V pll be feeded with global I/O pin clock
Hi
Sadly i got clock routed to non dedicated pin. I want to use pll in cyclone V device to get desired frequencies from it. Then i connect clock to pll i got the following error: The PLL reference clock input pin<pinname>was not placed in a dedicated input pin that can reach fractional PLL <PLL name> I added altctrlbuf but the error stays. Is it then possible to feed pll from non dedicated clock pin ? I read the documentation and I found that there is only requirement for global clock line.1 Reply
Altera_ForumSorry to be the bearer of bad news, but you can only feed PLLs from the dedicated clock inputs.
If you can add a loop to your board, from a spare I/O pin to a (hopefully free) dedicated clock input, you should be able to get something working. Route the clock you want out of the spare I/O pin so that, via your new loop, it feeds the dedicated clock pin. Note: this will add a little jitter but, assuming your mod is tidy, not enough to stop the PLL working. Cheers, Alex
