How should I connect a single-ended clock source the PLL inputs of a Cyclone? In the manual there are some examples of differential clock inputs and a note, that PLL can also accept single-ended inputs, but no example is provided. So what should I do -- connect the positive PLL_CLK input to the oscillator and the negative input to GND (directly or through a capacitor?)?
Best regards Piotr Wyderski
You don't need to connect the negative input to GND. Just connect your single ended clock to one of the CLK[3..0] inputs.
Easy as that.
For example, I connected CLK0 to a clock and CLK1 to a system reset.
What should I do with the unused inputs? Just leave them floating in the air?
Best regards Piotr Wyderski
Never have open indputs. They might self oscillate and draw a lot of power. Pull them low, pull them high, make the output.
Rene
-- Ing.Buero R.Tschaggelar - http://www.ibrtses.com & commercial newsgroups - http://www.talkto.net
If you mean I/O, then you are absolutely right, but I would like to know what should I do with unused CLKx inputs? The manual says that they don't have an alternative I/O function, so I am unsure whether these inputs need a special treatment. My first idea was "connect them to GND", but AMyler has told me "You don't need to connect the negative input to GND"...
Best regards Piotr Wyderski
Hi Piotr,
Just to clarify, when I said "You don't need to connect the negative input to GND" what I meant was that you can use the other CLK pin for another input such as your system reset, which can then use a global clock net to propagate around the device from that pin.
But if you don't need to use it at all then sure just go ahead and connect it to GND.
Alan
OK, now it's perfectly clear, thank you!
Best regards Piotr Wyderski
ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.