I was reading the Juergen Haible topic at the Electo-Music forum on the Trapezoid Generator.
http://electro-music.com/forum/topic-43206.html&postorder=ascI thought such a module might be interesting.
With limited panel space, I tend to try and use the CVS for control functions like this rather than building a dedicated module. I wrote a Trapezoid Generator program for the CVS with four dedicated controls/CV for Attack, On, Decay, and Off. The Start switch selects looping or gate controlled. Each phase has a 2 mS to 2 sec range. The output is a 0 to +5 volt trapezoid. I wrote only the main portion of the function and included "support.djb.bas" for the program support.
The program is on my programs page along with a scope image of an asymmetric trapezoid in looping mode.
http://modularsynthesis.com/programs/programs.htmIt should work on a PSIM although I have not tried it. You would have to select the appropriate conditional in the program.
Dave