Honored ContributorIn Cyclone III can I use PLL with input as a general purpose input pin (and not dedicated clock input pin) ?
I don't want delay compensation (which I already assume it wont be able to do). I just want a clock of frequency which is an N/D times that of the frequency of the clock coming in general purpose input pin. TIA
Honored ContributorAFAIK you can only use the dedicated inputs to feed a clock to a PLL, you can't use any general purpose pin for that on the Cyclone III
Honored ContributorIn cycloneIII handbook it is mentioned that "Clock control blocks that have inputs driven by internal logic are not able to 'drive' PLL inputs".
What exactly they mean by the term 'drive'? Is it that PLL wont give any output if I use an internal logic driven global clock buffer as an input to the PLL? Or is it just that PLL won't be able to compensate for the delay of the internal logic but will provide the desired output? Or is it something else?Honored ContributorAs a shortcut to the answer, simply notice that Quartus Place&Route fails, when you try to assign a different pin to drive the PLL. You may still want to know, why this is so, but it's a pure theoretical question for the time being.
Honored ContributorOkay! I will check it in the Quartus tool. Actually I am still getting familiar with the tool.
Meantime I have one more query. Can I drive a global clock buffer using general purpose input pin. (I dont intend to use it for driving PLL but just the logic elements and memory blocks)Honored ContributorYou can't directly drive a global clock from a general purpose pin. You can still use any input as a local clock for some logic though.
