Solution:
1) Draw the system diagram and Identify input and output variables..
- Input and output value definition:
Ki =1 when key “i” is pressed and K i =0 when key “i” is not pressed.
L 0 =1 causes the lock to open
2) Write out the truth table for the function:
Input Output
K 0 K 1 K 2 K 3 L 0
0 0 0 0 0
0 0 0 1 0
0 0 1 0 0
0 0 1 1 0
0 1 0 0 0
0 1 0 1 1
0 1 1 0 0
0 1 1 1 0
1 0 0 0 0
1 0 0 1 0
1 0 1 0 1
1 0 1 1 0
1 1 0 0 0
1 1 0 1 0
1 1 1 0 0
1 1 1 1 0
3) Use K-map or CAD to minimize the function and write the algebraic function.
Key
Controller
K 0
K 1
K 2
K 3
L 0
K 0 K 1 K 2 K 3
Keypad