Hi Friend,
It is very simple.
If you are using XG mode of DFT Compiler,
You just add control and observe testpoints in the script around the BB cores as shown below.
set_testability_configuration -type observe -clock_signal [get_ports [list YOUR_TEST_CLOCK ]]
set_testability_configuration -type control -clock_signal [get_ports [list YOUR_TEST_CLOCK ]]
//Adding observe points
set_test_point_element -type observe [get_object_name [get_pins A/B/<DRIVER CELL OF BB1 inputs>/Y]] \
-clock_signal YOUR_TEST_CLOCK \
-power_saving enable
//Adding control points
set_test_point_element -type control_01 [get_object_name [get_pins A/B/BB1/Y]] \
-clock_signal YOUR_TEST_CLOCK
Where BB1 is your black box.
If you are using DB mode,
set_wrapper_element A/B/BB1 -type shadow
set_port_configuration -cell <BB1> -port CLK -wrapper_exclude
//besure to exclude key ports if necessary
set_def_configuration -shadow_wrapper -autofix
create_test_protocol
dft_drc
insert_dft
..
.
Hope this helps your problem.
Sunil Budumuru,
www.asic-dft.com