Quartus® Prime Standard Edition User Guide: Design Compilation

ID 683283
Date 10/22/2021
Document Table of Contents

2.9.6. LogicLock Resource Exclusions

You can exclude certain resource types from a LogicLock region to manage the ratio of logic to dedicated DSP and RAM resources in the region.

If your design contains memory or Digital Signal Processing (DSP) elements, you may want to exclude these elements from the LogicLock region. LogicLock resource exceptions prevent certain types of elements from being assigned to a region. Therefore, those elements are not required to be placed inside the region boundaries. The option does not prevent them from being placed inside the region boundaries unless the Reserved property of the region is turned on.

Resource exceptions are useful in cases where it is difficult to place rectangular regions for design blocks that contain memory and DSP elements, due to their placement in columns throughout the device floorplan. Exclude RAMs, DSPs, or logic cells to give the Fitter more flexibility with region sizing and placement. Excluding RAM or DSP elements can help to resolve no-fit errors that are caused by regions spanning too many resources, especially for designs that are memory-intensive, DSP-intensive, or both. The figure shows an example of a design with an odd-shaped region to accommodate DSP blocks for a region that does not contain very much logic. The right side of the figure shows the result after excluding DSP blocks from the region. The region can be placed more easily without wasting logic resources.

Figure 32. LogicLock Resource Exclusion Example

To view any resource exceptions, right-click in the LogicLock Regions window, and then click LogicLock Regions Properties. In the LogicLock Regions Properties dialog box, select the design element (module or entity) in the Members box, and then click Edit. In the Edit Node dialog box, to set up a resource exception, click the Edit button next to the Excluded element types box, and then turn on the design element types to be excluded from the region. You can choose to exclude combinational logic or registers from logic cells, or any of the sizes of TriMatrix memory blocks, or DSP blocks.

If the excluded logic is in its own lower-level design entity (even if it is within the same design partition), you can assign the entity to a separate LogicLock region to constrain its placement in the device.

You can also use this feature with the LogicLock Reserved property to reserve specific resources for logic that will be added to the design.