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AR# 7655

XPLA2 - Grouping signals in a fast module


Keywords: XPLA, CoolRunner, XPLA2, fast, module, group, signals

How do I group signals in an XPLA2 fast module?


Since signals that traverse the global ZIA incur either a 2nS (XCR320) or 4nS (XCR960) delay, it is sometimes necessary to group timing-critical signals within a fast module.

This is accomplished using the property, FM_GROUP. This property can be specified in a ABEL source file or in a control file.

Example: (Please note the spacing.)

fm_group siga sigb sigc

This instructs the fitter to place the list of signals specified with this property in the same fast module. Note that the use of this property alone does not specify a particular fast module for the placement of the signals; it only indicates that these signals should be grouped together. To specify a particular fast module for the group of signals, simply assign one of the signals in the group a node or pin number from that fast module.
AR# 7655
Date Created 08/21/2007
Last Updated 07/28/2009
Status Archive
Type General Article