## December 22, 2015

### Puzzle: Stuck-at Fault

Around 2.5 years back, I had posted a Puzzle: Stuck-At Fault on this blog where I had asked to find the input vector to detect a particular stuck-at fault in a given circuit. This puzzle is exactly the same problem, but with a more complex circuit.

Assuming a SINGLE STUCK-AT FAULT MODEL, could you please help me with the input vector to detect:

1. A Stuck-at-0 fault at node L.
2. A Stuck-at-1 fault at node L.

1. {F,D,A,B,I,H} for
Stuck at 0 : {001X00}, {00X100}Stuck at 1 : {01XX00}, {0X0000}

1. Hi Reyaz,

Could you please elaborate why do we need two sets of vectors for detecting each fault? That should be the case for delay testing (transition faults).

Please correct me if I'm wrong.

2. Here Reyaz meant to say that any vector will work but not as a set of vectors I guess.

3. Yes, BHOG. Correct.
Naman,
Sorry if it is not clear. For detecting L0 fault, any of the vectors {001000, 001100, 000100} can be used. For L1 fault, any of the vectors {010000,010100,011000,011100,000000} can be used.
You just need to see which input will sensitize the node to flip from the stuck state.

4. why I and H are 1 ,it can be 00,01,10
why F is 0, it can be X all these for L0.