Answers Database

M1.2/M1.3/M1.4 PAR (MAP): CLB Pin locking is not supported


Record #2569

Product Family:  Software

Product Line:  Merged Core

Problem Title:
M1.2/M1.3/M1.4 PAR (MAP):  CLB Pin locking is not supported


Problem Description:
Keywords: clb pin lock, map, par, .FFX, .FFY, 18417

Urgency: standard

General Description:
In the M1.2 and M1.3 releases of PAR, you cannot lock signals
to specific CLB pins.  This ability was formerly supported
in the pre-M1 XACT software.

This capability is not supported in the M1 software.  In the
M1 release, PAR may swap signals within the same CLB wherever
it deems this is necessary.

Lack of support for CLB pin locking also means that .FFX and
.FFY constraints (locking down a flipflop to a particular CLB
flipflop) will not work either, since such constraints would
constrain the associated flipflop output pin to particular
pins on the CLB.   PAR will ignore these constraints if it
thinks it can do a better job.

Similarly, .F and .G constraints constraining combinational
logic to either an F or G function generator also will be
ignored by PAR, since constraining a signal to a particular
function generator also implies you are constraining it to a
particular set of pins.




Solution 1:

The workaround if a specific configuration of a CLB or
set of macro CLBs is required is to implement the
configuration in the EPIC Design Editor and generate a
physical macro out of the configured CLB.  You must
then generate a symbol for this macro and instantiate
it in your design.




End of Record #2569