| ISTANDARD |
See XP IOB Supported Standards and set the
same IOSTANDARD value used in the nibble |
The nibble’s input IOSTANDARD must be defined when
the XPIO_VREF unisim is used. |
| VREF_NIB |
VREF_FABRIC |
When using the XPIO_VREF primitive to adjust the VREF level for a
nibble, VREF_FABRIC must be selected. |
| VOH (optional) |
80 |
Only set this attribute when SSTL15 is being used to
interface to a SSTL18 compatible VREF level (i.e., centered around 900
mV). In this case, VOH should be set to 80. Care must be taken when
interfacing to SSTL18 drivers. Data sheet input thresholds must be
verified, and external termination must be used. |