The RocketIO Wizard creates an HDL file with a BREFCLK port for each transceiver instance. Only two BREFCLK pin sites are present on a chip, and the following error is reported:
"ERROR:Place - Component BREFCLK_BLK3 has no site left to place."
How do I connect the ports to these pins?
The connections depend upon the placement of the transceiver instances. The BREFCLK and BREFCLK2 pins at the top of the chip must feed any transceiver that is placed at the top of the chip; the BREFCLK and BREFCLK2 pins on the bottom of the chip must feed any transceiver placed on the bottom of the chip.
For example, four RocketIO transceivers exist in an XC2VP4 -- two on the bottom, and two at the top. To create an HDL file with four transceivers using the RocketIO Wizard, you must connect the BREFCLK pin on the bottom of the chip to the two transceivers placed on the bottom, and the BREFCLK pin at the top to the two transceivers placed at the top.