How to use PLL?

Altera_Forum · ‎09-24-2005

Hi:

We all konw that Altera provides PLL,These PLLs offer clock multiplication and division, phase shifting, and

programmable duty cycle and so on.But I don't know how set PLLs when I change the setting of PLLs in my program. For example,modify clock multiplication and division in my program.

Thanks

Altera_Forum · ‎09-29-2005

Hi,

Due to the internal implementation of PLLs in Altera FPGA (at least for Cyclone) devices, duty cycle, phase shift, and so on, are not software programmable. You only have the ability to modify them at design time. Take a look at the Cyclone device manuals, they have included very usefull information about this subject.

Altera_Forum · ‎09-29-2005

PLL's are a device-specific thing and on some devices, they do support "reconfiguration" on the fly. Cyclone doesn't happen to be one of those devices, but I believe that both Cyclone II and Stratix II do support this feature.

- slacker