Question: A traffic light controller receives a 4 - bit input that changes every 5 seconds. The input sequence is a simple counter that counts from

A traffic light controller receives a 4-bit input that changes every 5 seconds. The input sequence is a simple
counter that counts from binary 0 to binary 15 and then starts again from binary 0. These signals go to 4 outputs,
NSH, NSL, EWH, EWL. The first two outputs NSH and NSL respectively represent the high and low bits that
are fed to the lamps that face in the North-south direction. The other two outputs EWH and EWL respectively
represent the high and low bits that are fed to the lamps that face in the East-West direction. The following table
indicates how setting the high and low bits determines the color of the lamp:
High Low Lamp Color
00 Green
01 Yellow
10 Red
11 Red
Each light should be green for 30 seconds, yellow for 5 seconds, and then red for 45 seconds. There should
be two 5 second intervals when both lights are red. Assume that for the interval where the input is 0000, the
North-South light has just turned green, and the East-West light has been red for 5 seconds already.
Design the circuitry that feeds from ABCD to the two outputs. You may represent your answer as algebraic
equations (make sure to simplify).

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