Achronix ACE Version 5.0 - Manual (Page 309)

Placement Regions and Placement Region Constraints Chapter 4. Tasks
Placement Regions and Placement Region Constraints
Placement Regions and Placement Region Constraints are an advanced feature, and
should only be used under the guidance of an Achronix FAE. Unguided use of placement
region constraints can cause loss of QOR, and may make a design impossible for the
Placer or Router to solve.
Placement Regions are user-defined rectangular areas of the core fabric (not the IO Ring), to which the user
can inclusively constrain the placement of multiple instances from their design, without the user needing to
manually assign instances to specific sites within that region.
Because of clock distribution limitations, only a finite number of clocks can be routed to each Clock Region
in the fabric. Placement regions allow advanced users to ensure that those constraints are met if the
automated tools need guidance. When necessary, clocked instances (flops, BRAMs, etc) may be constrained
to placement regions to guarantee ACE doesn’t attempt routing more clocks into a region than the region
can support.
Placement Regions and the associated instance placement constraints may be manipulated through Tcl, or
via the ACE GUI using the Floorplanner view and Placement Regions View. The Search View, Selection
View, Critical Paths View, and Netlist Browser View may also be used to assign instance placement
constraints.
Users should be aware that Placement Regions are not treated as distinct objects in the ACE design database,
thus they do not have their own
object type prefix , nor are they directly searchable in the Search View or
with the Tcl find command.
Placement Regions (and constraints) are only supported for the 22iHD products. Behavior
with other products (including the members of the 22iHP family) is undefined.
Placement Region Preferences
There are a number of user preferences which may be configured to alter how the mouse creates Placement
Regions and assigns Placement Region constraints. These preferences are found on the
Placement Regions
Preference Page .
Creating a new placement region
Placement regions may be created/defined by using the mouse in the Floorplanner View, or by directly
calling the Tcl command
create region . In both cases, the bounds of the created region may ”snap to”
(grow to encompass) the entirety of all enclosed Clock Region boundaries or tile boundaries.
To create a Placement Region using the mouse in the Floorplanner view:
1. Ensure the Floorplanner’s Placement Region Tool ( ) is active.
2. (Optional) If the Placement Region is meant to align with one or more Clock Regions , enable the
overlays for those regions from the Clock Regions view . This will not affect the functionality in any
way, but will make it easier to know where to define the region bounds.
3. Press and hold the left mouse button at one of the corners of the area to be defined as the new
Placement Region
4. While still holding the left mouse button, drag the mouse to the opposite corner of the desired
Placement Region area. Release the left mouse button when the mouse reaches the desired location.
5. ACE calculates the enclosed subtile grid coordinates, growing as necessary to ensure all partially-
enclosed subtiles are fully enclosed.
6. The Create Placement Region Dialog pops up pre-populated with the calculated subtile coordinates
297 http://www.achronix.com UG001 Rev. 5.0 - 5th December 2012