Abnormal initialisation time and workaround

A project log for VHDL library for gate-level verification

Collection of ASIC cells and ProASIC3 "tiles" in VHDL so I can design and verify optimised code without the proprietary libraries

Yann Guidon / YGDESYann Guidon / YGDES 08/16/2020 at 17:470 Comments

In the log 124. TAP timing & simulation I encountered a strange situation : the simulation would appear to take much longer than expected. This occurs after elaboration and during the first wait of the driving process.

This did not appear before because I think 2 factors played together for the first time :

Unfortunately I'm not able to trace what happens exactly but here are some tips :

In practice, the last tip can be a good compromise : it's not as fast as a behavioural model but less heavy than the "full trace" that is the default option.

However the "full trace" and "simple" libraries don't cohabit well but the design flow could require them both, depending on the level of analysis to perform. I have chosen to add a "simple" sub-directory in the latest version, where the homonymous version is built separately from the "full trace" version. Scripts using GHDL can then select which version is used on a case-by-case basis, depending on the requirements, by selecting the right path.

For the #YGREC8 this saves some seconds and uses more room but this is necessary because the tracing version can't analyse properly the sequential gates for now.