Clk pin for RTL on ultra96v2


Been looking around various forums and I can’t seem to find a direct answer to the question.

If one is doing a pure RTL design on the 96 board is there no clock pin?
I can’t seem to find anything clear in the constraints file - online tutorials and blogs suggest that you have to grab the clock off the zync feed it to a clocking wizard and then go through the whole rigamarole of Vitis & fur- I mean bootloaders XD

I’ve gotten the above to work but it’s rather convoluted, just for a clk.


Hello L,

Ultra96 was always intended to be used as a hybrid system, with both the PS and PL. In other design examples, PL clocks are derived from the PS clock. There is no separate, PL-only oscillator on the board.

Are you interested in attaching an external oscillator to a clock capable pin on the expansion connectors?

For RTL-only designs, you might be better suited with something like the Arty-S7 (


Oh eventually I will be integrating in the hardcore processors, but in terms of debugging the RTL it just adds hassle having go into SDK and all + the time to synth added block design.

External clk would I suppose be the only option then. Do you have any recommendations?


  • L

Look for anything with “GC” or “HDGC” in the Xilinx pin name attached to the expansion connectors. The GC stands for Global Clock and the HDGC is a Global Clock on a High Density bank. For example, you have access to all of the following MPSoC pins through the expansion connectors:
E8, D8, D7, D6, D5, C5, L1, L2

The latest v1.1 UG for Ultra96-V2 has the full pin tables. Look at Tables 7 and 8.

Oh I mean do you have any recommendations for an external clk source

We used the IDT Versaclock 6E for all the internal clocks on Ultra96-V2. It is the 5P49V6975A114LTGI on Sheet 7 of the schematics. It is a really versatile device. The programmability made it very easy to configure exactly what we needed in our system. I wrote about that design here:

You could get the Eval Board and see if you could figure out a way to connect it to one of the expansion connector GC/HDGC pins.