Question

2. Consider the following circuit to control a moving walkway. Every 2 seconds, the circuit examines two weight sensors and decides if the walkway will travel Northward or Southward or be turned off. There is a weight sensor in the North half of the walkway and a weight sensor in the South half of the walkway. If both sensors detect zero weight, the walkway is turned off. If the walkway is off and both sensors detect weight, the walkway remains off. If the walkway is off and one of the sensors detects a weight, the walkway starts moving in the opposite direction, i.e., if the North weight sensor detects a weight, the walkway starts moving Southward. Once the walkway is in motion, it retains that motion until both weight sensors detect zero weight. (60 points)

a) What are the states for the circuit controlling the walkway?

b) What are the inputs to the circuit and what values can those inputs have?

c) Draw the finite state table and finite state diagram for this circuit.

d) Identify one example scenario where you would want the circuit's behavior to be different from what is specified above.

Answer 1

Amd As peg the given conditions in the pooblem, we have three States, d, Walkaway should be obt 2, LOIKAWOy moving in Nooth 3. walk way moving in south - we need at least 2 bits to represent these 3 States: a) OFF, North, south, it is unused 00) C10 (01) .: sted. 62 sensor i and sensor 2 -> 2 inputs CNorth) csouth). -> Feedback is walkway poevious state. c) state table se diagram: inputs present state Next state of (sensors) of walk way: walk way. SN ss WN WS : WN WS. Chooch) (south) (Nooth) (south) chooch) (south 0 0 0 0. 0 0. 0 0 0 0 0 · 0 0 0 0 0 o O i : unused state į O conto

SN SS. waren) csouth - WN WS. CNooth) south) WN WS. cvorth) csouth) olo urused state -oo- 0 i ---o00o- 0 inued 0 II ... 0 ..(scenario) State 0 x1 1.1 o rused state - The state li is cinesed state. because moving walkway cannot move in both the directions at the same time. lol 100. - States 00OFF 01 → Moving south 10 Moving North A a ol i o. Ja state diagoam

1 There is an example of scenario where the circuit behaviour should be different. o If both the inputs are al and present walkway is oo then the next walkway state will be 00., this is the point gulen in the pooblemi itself. > But in the scenario in the present walk - - Woys are 01. 10 there the output is undeteomined. In this sitciation, cacuit behaviour should be determined. :