I am observing a strange behaviour on a Trenz module.
I have a PCIe x4 interface in B225 as part of the Kintex Ultrscale DMA IP, with B65-L3N connected to CLKREQ in the PCIe slot, but without any constrain for it.
I have this constrain in the main xdc:
set_property BITSTREAM.CONFIG.UNUSEDPIN PULLNONE [current_design]
For some reason, that signal pulls down after programming.
Is that possible? I see that the PCIe core in the DMA does not manage CLKREQ at all, so I was wondering how can that be.
We only have two FET isolators in the line (one on each side of the connector), no pullups or downs.