Input buffers, 3-state outputs, and bidirectional buffers can have a weak pull-up resistor, a weak pull-down resistor, or a weak keeper circuit. PULLTYPE attribute has the following possible values.
This feature can be invoked by adding the following possible constraint values to the relevant net of the buffers. These attributes use the following syntaxes in the XDC file:
set_property PULLTYPE value [get_ports port_name]
For more information on implementing these attributes on either individual I/Os or globally for all I/Os, see the pull-up, pull-down, and keeper descriptions in the Vivado Design Suite Properties Reference Guide (UG912) [Ref 6].