When you read an SDC file from the command line, it works fine. When you read it using a Tcl procedure, it won’t work, because the global variables cannot be accessed. Here’s how to fix this annoying problem.
This is an old, old post, but over the years it continues to be one of my most popular pages. I leave it here in the hope that it is still useful. Please add your corrections or comment. –John
It is good design practice to use as few SDC files as possible. This post describes a way to create a single SDC file that can be used both before and after clock tree synthesis (CTS), and by both Cadence PKS and SoC Encounter. More