Dynamic clock selection in Cyclone 4E

There are plenty of resources on the device and an intended way to use them. Assuming you're trying to drive a block of logic with one of four clocks, then you're trying something that, I'm pretty sure, isn't an intended mode of operating.

The only way I can see this working is if you have an external loop, something I frequently design into hardware. You can select one of your four clocks, drive it off the device and back into a dedicated clock pin which is used to drive your logic. That way you can chose which clock to use.

This method will result in greater jitter and an unpredictable delay to the resulting chosen clock. Depending on your application, neither of these may be of concern. Your choice if that is something you can live with.

Regards,

Alex