The picture below shows the intersection of a road. Some vehicle detection sensors are placed along lanes C and D (main road) and lanes A and B (access road). These sensors outputs are LOW (0) when no...

The picture below shows the intersection of a road. Some vehicle detection sensors are placed along lanes C and D (main road) and lanes A and B (access road). These sensors outputs are LOW (0) when no vehicle is present and HIGH (1) when a vehicle is present. The intersection traffic light is to be controlled according to the following logic:

1. The east-west (E-W) traffic light will be green whenever both lanes C and D are occupied.


2. The E-W light will be green whenever either C or D is occupied but lanes A and B are not both occupied.


3. The N-S light will also be green whenever both lanes A and B are occupied but C and D are not both occupied.


4. The N-S light will also be green when either A or B is occupied while C and D are both vacant.


5. The E-W light will be green when no vehicles are present.

Using the sensor outputs A, B, C and D as inputs, design a logic circuit to control the traffic light. There should be two outputs-S and E-W that go HIGH when the corresponding light is to be green. Simplify the circuit as much as possible and show all steps.

Complete the following with the step-by-step procedure.

1. Interpret the problem and set up a truth table to describe its operation.


2. Write the AND (product) term for each case where the output is 1.


3. Write the sum-of-products (SOP) expression for the output.


4. Simplify the output expression if possible.


5. Implement the circuit for the final, simplified expression.