Honored Contributor
Honored ContributorThe PLL input clock will need to come from a dedicated pin. You won't be able to select one of two unless the PLL supports this.
A quick look through the serial digital interface (sdi) megacore function user guide (https://www.google.com.ua/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=0cbsqfjaaahukewjshvugofvhahuevj4khwl4brg&url=https%3a%2f%2fwww.altera.com%2fen_us%2fpdfs%2fliterature%2fug%2fug_sdi.pdf&usg=afqjcney2c4muerg1n9m0-5whyhnsdwuig&bvm=bv.102829193,d.cww) tells me - on page 3-3: --- Quote Start --- Internal switching between two reference clock signals in the transmitter block. This feature is optional and only available for Arria II GZ, Stratix IV GX , and HardCopy IV devices. --- Quote End --- Your tittle suggests you're using ArriaII GX. So, you may struggle to do what you want to. Cheers, Alex
