ATPG constariant Vs cell constraint

[shakti_pattnaik]

What's the difference b/w "add atpg constraint" and "add cell constraint".

 

[pete_lu]

add cell constraints are used to control the load and unload values allowed on scan cells. And TM will create patterns that satisfy cell constraints. It only works in DRC mode.
add atpg constraints is used to define constraints that are required to be satisfied during ATPG. Also the constraints can be selected to be considered during DRC process. It works in DRC and TEST mode.
To use add atpg constraints command, I recommand you to use add pi constraints to constraint the design input. This command is more complete and more thoroughly propagated during DRC checks and simulation checks.