To use the FPLL in UltraScale+ GTY the Tcl commands below need to be run.
Follow these steps:
Tcl script editing instructions:
The line below sets the numerator of the fractional part:
If this value is 0.5, 0400000 would be 0.25 and so on. Edit this line to set the fractional part to what you need.
The line below sets the integer part of the feedback divider:
The integer part of the feedback divider is in hex and you add two to the value to get the actual divide value the hardware implements, so the actual value of the divider here is 82 decimal.
The combined settings in the attached script are 82.5 decimal.
If you do not wish to apply the same fractional setting to all lanes in your IBERT then you will need to edit this script to only change the lanes you need the fractional setting on.