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sphilipp's avatar
sphilipp
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3 years ago

Connect external clock via non-dedicated pin to PLL on Cyclone 10 LP

Hi everyone I have a PCB that I cannot change, on which a clock is connected to a non-PLL-dedicated pin. I was indeed trying to use a PLL, but Quartus 20.1.1 Lite software hinders to connect the PLL ...
sphilipp's avatar
sphilipp
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3 years ago

Thanks sstrell,

unfortunately, it seems not possible on Cyclone 10 LP:

If I directly connect the pin to the PLL I get:

Error (176554): Can't place PLL [...] -- I/O pin [..] (port type INCLK of the PLL) is assigned to a location which is not connected to port type INCLK of any PLL on the device

If I add some combinational logic (inverter) I get:

Error (15065): Clock input port inclk[0] of PLL [..] must be driven by a non-inverted input pin or another PLL, optionally through a Clock Control block

Info (15024): Input port INCLK[0] of node [..] is driven by [..] which is COMBOUT output port of Combinational cell type node [..]

(I replaced signal names by "[..]")

The latter error message also shows up if I use "pin - inverter - global - pll", although "pin - inverter - global" is usually valid and plls can be driven by globals.

The check seems to be implemented in Quartus and my question is if there is a way round.

Stefan