SNAPPING_MODE property automatically
resizes Pblocks to ensure no back-to-back violations occur for 7 series designs. When
SNAPPING_MODE is set to a value of
creates a new set of derived Pblock ranges that are used for implementation. The new
ranges are stored in memory, and are not written out to the XDC. Only the
SNAPPING_MODE property is written out, in addition to the
normal Pblock constraints.
In 7 series devices the structure is such that the routing resources, called interconnect tiles, are placed adjacent, or back-to-back. When floorplanning for partial reconfiguration, it is important to understand where these back-to-back boundaries exist. If a Pblock splits these paired interconnect tiles, it is called a back-to-back violation. For more information on back-to-back interconnect please refer to Creating Reconfigurable Partition Pblocks Manually.
The original Pblock rectangle(s) are not modified when using
can still be resized, moved, or extended with additional rectangles. Whenever the
original Pblock rectangle is modified, the derived ranges are automatically
SNAPPING_MODE property is supported in batch mode, so
there is no requirement to open the current Pblock in the Vivado IDE
to set the
SNAPPING_MODE value, although this option is available when
performing interactive floorplanning, as shown in Automatic Adjustments for Reconfigurable Partition Pblocks.
When you set the
SNAPPING_MODE property using the following syntax (or by selecting the Pblock Property as shown above), the implementation tools automatically see the corrected Pblock ranges.
set_property SNAPPING_MODE ON [get_pblocks <pblock_name>]
The following table shows
SNAPPING_MODE property values for 7 series devices.
|Default for 7 series. No adjustments are made and DERIVED_RANGES == GRID_RANGES
|Fixes all back-to-back violations.
|Same behavior as ON, except for the following exceptions:
SNAPPING_MODE property also works in conjunction with
RESET_AFTER_RECONFIG requires Pblocks to be vertically frame (or clock region) aligned. When
SNAPPING_MODE is set to
ON or to
RESET_AFTER_RECONFIG is set to
TRUE, the derived ranges automatically include all sites necessary to meet this requirement.
Automatic Adjustments for Reconfigurable Partition Pblocks shows the original user-created
Pblock in purple.
RESET_AFTER_RECONFIG has been enabled, and both left
and right edges split interconnect columns. By applying
the resulting derived Pblock (shown in yellow) is narrower to avoid
INT-INT boundaries, and taller to snap to the height of a clock