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Altera_Forum
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16 years ago

Adding a second PLL to Cyclone III EP3C16

Connecting a PLL to the first input clock (pin 31) compiles OK. But when I try to add a second PLL driven from the second clock pin (pin 32) I get the following error: Error: promoted fro...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
16 years ago

1) For this second one, look at where the pin is placed(which dedicated clock inputs).

2) Look in the handbook and see what PLLs that can drive for your device.

3) Look in the Compilation Report -> Fitter -> Resource Section -> PLL Summary and find where this one is placed(which won't be by the one you'd expect.)

If you want to visualize any of this, right-click on the name and Locate to Chip Planner(note this is a die view, so it may be flipped left to right if it's in a flip-chip package)

I'm guessing something will jump out as to what's going on. By default, if a pin is on a dedicated clock input and drives a PLL that is available, the fitter will always place them next to each other.