2.1.3. Compile Components Independently
Establish a margin for the speed you require for each component. For example, when targeting a 20% timing margin, a component with 19.5% margin is a failure. Base your timing margin targets on the component context. For example, you can allow a timing margin of 10% for a high-level component representing half the chip. However, if the rule is not explicit, the margin can erode.
Use the Chip Planner to visualize the system level view. The following Chip Planner view shows a component that uses 5% of the logic on the device (central orange) and 25% of the M20K blocks (red stripes).
The Chip Planner system view indicates nothing alarming about the resource ratios. However, significant routing congestion is apparent. The orange memory control logic fans out across a large physical span to connect to all of the memory blocks. The design functions satisfactorily alone, but becomes unsatisfactory when unrelated logic cells occupy the intervening area. Restructuring this block to physically distribute the control logic better relieves the high-level problem.
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