Answers Database

PAR M1.3 - XC4000E designs ported to XC4000XL may have unroutable carry chains.


Record #2408

Product Family:  Software

Product Line:  Merged Core

Problem Title:
PAR M1.3 - XC4000E designs ported to XC4000XL may have unroutable carry
chains.



Problem Description:
The XC4000XL and XC4000EX parts support only bottom to top
carry chains. The XC4000E parts support both top to bottom
and bottom to top carry chains, so designs originally targeted
for these parts may contain RPMs with carry chains that are
unroutable in the XC4000EX and XC4000EX parts. This condition
is flagged by PAR.


Solution 1:

This problem can be avoided by modifying the input
design or by re-mapping the design using the -ir switch
which specifies that RLOC constraints be used to guide
mapping of CLBs, but not to determine relative location
of CLBs. This will allow PAR to create a routable placement.



End of Record #2408