Electronic – Question on Logic circuit and Karnaugh Map

boolean-algebrakarnaugh map

I got this question from a university site and thought of attempting it to test my knowledge in Logic circuits, Boolean alg and Karnaugh graph. Problem is, I have been scratching my what logic circuit is coming out; I am not able to translate this into a known Boolean Algebra.

The Question:

A vehicle seat belt circuit is such that the car should only start if the driver’s seat belt is
fastened and either the front passenger seat is unoccupied or the front passenger seat is
occupied and the passenger seat belt is fastened.
Obtain a truth table, boolean equation and Karnaugh graph.

I need help on the truth table.

Suppose:

A: Driver seat belt

B:Passenger seat occupied

C:Passenger Seat Belt

Considering A, B and C, I get this truth table, but see my comments below:

   A    B     C   B??C    A AND(B??C)
  ---  ---  ---   ----    --------
    0    0    0   1       0
    0    0    1   1       0
    0    1    0   0       0
    0    1    1   1       0
    1    0    0   1       1
    1    0    1   1       1
    1    1    0   0       0
    1    1    1   1       1

When I consider B and C (Passenger seat occupancy and Passenger seat belt:
When there is no passenger, Passenger seat belt does not matter as long as driver seat belt on. these are represented by B??C. The problem is, I am not able to figure out what Boolean condition this is: AND, XOR, NOT, etc. This is what is making it difficult for me to produce the resulting Boolean Algebra for subsequent questions. Help.

Best Answer

 B   !B    C   B??C
---  ---  ---  ----
 0    1    0    1
 0    1    1    1
 1    0    0    0
 1    0    1    1
 0    1    0    1
 0    1    1    1
 1    0    0    0
 1    0    1    1

Do you see it now?