To Generate a Single Test Vector to detect all/most number of faults in a given set

1. To Generate a Single Test Vector to detect all/most number of faults in a given set Project by: Arvind Raghuraman Course Project ELEC 7250 Raghuraman: ELEC7250

2. Problem Statement • The Objective of the project is to determine a test vector that could detect all/most number of faults in a given set. • As a suggested improvement investigation was done on extending the algorithm developed for test set compaction. Raghuraman: ELEC7250

3. Background work Major Combinational ATPG Algorithms: • D-Algorithm (Roth) -- 1966 • PODEM (Goel) – 1981 Advanced ATPG Algorithms: • FAN – Multiple Backtrace (1983) • TOPS – Dominators (1987) • SOCRATES – Learning (1988) • Legal Assignments (1990) • EST – Search space learning (1991) • BDD Test generation (1991) • Implication Graphs and Transitive Closure (1988 - 97) • Recursive Learning (1995) Raghuraman: ELEC7250

4. ATPG / Vector Detection Algorithm SET – Fn {TFn1, TFn2, ....TFnm} Combinational circuit ATALANTA ATPG F1 - > (TFn1) = {TV1,TV4,TV6} F2 - > (TFn2) = {TV7, TV8,TV6,TV1} F3- > (TFn3) = {TV27, TV5,TV6,TV13} Bench file for the given combinational circuit …….. TFnm Equivalence Collapsing and ATPG Output From ATALANTA ATPG SET - TVFn = {TVFn1, TVFn2, ....TVFnm} TV1 - > (TVFn1) = {f1,f4,f6} R = MAXIMUM Set Size (SET - TVFnm)  TVx TV2 - > (TVFn2) = {f7,f8,f6,f1} Test Vector TVx Detects the most / All Faults in the given combinational Circuit TV3- > (TVFn3) = {f27,f5,f6,f13} …….. TVFnm Set Manipulation Raghuraman: ELEC7250

5. Snap Shot of the application Raghuraman: ELEC7250

6. Suggested Improvements Test Compaction strategy: • The vector TVx and the faults detected by the vector are dropped from the parent lists. • Now by rerunning the same algorithm we get another vector that detects the most number of faults. • Repeat step 1. • By repeating the process and by keeping track of the fault coverage after every iteration we can obtain a compact test set with required fault coverage. Raghuraman: ELEC7250

7. Results Circuit under Test : c17.bench combinational circuit • Number of test patterns : 54 • Fault coverage : 100.000 % • Number of collapsed faults : 22 Application output Test Vector " 000xx " detects 1 faults Test Vector " 001xx " detects 1 faults Test Vector " 00xxx " detects 2 faults Test Vector " 010xx " detects 3 faults Test Vector " 0110x " detects 5 faults Test Vector " 0111x " detects 3 faults Test Vector " 100xx " detects 4 faults Test Vector " 10111 " detects 1 faults Test Vector " 101x0 " detects 1 faults Test Vector " 101xx " detects 2 faults Test Vector " 110xx " detects 3 faults Test Vector " 11100 " detects 2 faults Test Vector " 11101 " detects 1 faults Test Vector " 11110 " detects 1 faults Test Vector " 11111 " detects 1 faults Test Vector " 1111x " detects 2 faults Test Vector " 1x1xx " detects 1 faults Test Vector " x0011 " detects 1 faults Test Vector " x00x0 " detects 1 faults Test Vector " x00x1 " detects 3 faults Test Vector " x0101 " detects 3 faults Test Vector " x0111 " detects 2 faults Test Vector " x0xx0 " detects 1 faults Test Vector " x101x " detects 1 faults Test Vector " x10x0 " detects 1 faults Test Vector " x10xx " detects 2 faults Test Vector " x1100 " detects 1 faults Test Vector " x110x " detects 1 faults Test Vector " x111x " detects 2 faults Test Vector " xx111 " detects 1 faults Application Result Test Vector " 0110x " detects 5 faults Raghuraman: ELEC7250

8. Conclusion • The Application developed correctly identifies the test vector of interest. • The proposed strategy for test compaction should be tested on other circuits and its performance should be ascertained. • The Application can be used as a Generic Tool for any combinational circuits, it can directly accept the output file from ATALANTA and generate the test vector of interest. Raghuraman: ELEC7250

9. References • Class Lecture Notes ELEC 7250 • Essentials of Electronic Testing, Michael L.Bushnell, Vishwani D.Agarwal Raghuraman: ELEC7250