AR# 2777: M1.5 PAR/EPIC - Both incorrectly report that BEL doesn't exist in the NCD
M1.5 PAR/EPIC - Both incorrectly report that BEL doesn't exist in the NCD
Keywords: BEL, PAR, EPIC, timespec
General Description: PAR and EPIC both incorrectly report that a BEL doesn't exist in the NCD. The PCF file contains a TIMEGRP, which contains the BEL.
When the NCD and PCF files are loaded into either PAR or EPIC, they issue warnings that the BEL was not found. However, visual inspection through EPIC confirms that the BEL does exist.
When the mapper creates comps, it will fill them with the appropriate BELs. With these BELs, you can attach timing constraints.
The problem arises when you run the Logic Block Editor in EPIC and modify a comp that contains BELs. Since you cannot guarantee that you will always create a valid COMP, as far as connectivity and programming, when you exit LBE, the COMP will be turned into what is known as a "SuperBel", where the system treats the entire COMP as a BEL. Hence, any BELs internal to that comp will be removed, thus rendering any timing constraints that reference those BELs useless.
This is a known problem. The only work-around is to not modify CLB's, IOB's, or other COMPs that are pointed to by a time group or a timing constraint.