Here is an example of using the random ATPG with default options:
 

prompt> random c17	*give the name of the design to the random ATPG*
Random Test Pattern Generator Reading SSBDD-model file c17.agm... OK Allocating test patterns... OK Generating...  Starting random test pattern generation   Tested 22 of 22 faults Fault coverage: 100.000000  6 vectors generated Allocating test patterns... OK OK Time, used by process: 0.030000  Writing test patterns file c17.tst... OK

The random ATPG can be adjusted using several options as -failure_limit, -pack_size, -criterion, -packages, and -select_max (the explanation of each option is given in TT manual). It was enough to increase the package size and to allow the generator to choose only one (the best) pattern from each package to achieve the goal:

 

prompt> random -pack_size 2 -select_max 1 c17 Random Test Pattern Generator	*the package size is two times bigger (64 patterns)* *and the selection is restricted to a single pattern*
Reading SSBDD-model file c17.agm... OK Allocating test patterns... OK Generating...  Starting random test pattern generation   Tested 22 of 22 faults Fault coverage: 100.000000  4 vectors generated Allocating test patterns... OK OK Time, used by process: 0.070000  Writing test patterns file c17.tst... OK

Other options can help to deal with big or hadly testable circuits.

Last update: 28 July, 2004