A = Car is at the gate (1 if at gate; 0 otherwise)

B = Position signal (complicated)

(by default, the gate is low to block passage)
Gate opens at A=1 and V=1
- If A switches to 0 before V=0, then gate closes
As soon as the car is no longer detected (likely when the car has passed the gate), lower the gate
R=1 means “raise” and L=1 means “lower”
- While the gate is being moved, the R or L must be held at 1 so the gate doesn’t stop at the middle (I’m guessing only for the cycles where it hasn’t finished moving)
  - Means R and L cannot change unless B has changed to 1.
B will be 1 when the gate has reached one of the two final positions (fully open or closed)
- B is also 1 if it’s in one of the discrete states
Ensure the gate doesn’t attack people

Lifting (1X0) (just verified)

Lowering (0X0)

Up (1XX)

Down (0XX) (only when A=V=1 does it go to raising) (stays down UNLESS A=V=1) If A=0 before V=1, then stay closed

Part A: 2

Part A: 3

Since there are 4 states, we would need ceil(log_2(4)) = 2 bits minimum to store the 4 states.

Flip flop values to state assignments:

F1	F0	AVB	newF1	newF0
0	0	0XX or 10X	0	0
0	0	11X	0	1
0	1	0XX	1	1
0	1	1X0	0	1
0	1	1X1	1	0
1	0	1XX	1	0
1	0	0XX	1	1
1	1	0X0	1	1
1	1	1XX	0	1
1	1	0X1	0	0

(This was when i thought it was a mealy machine)

State Table (Part A):

Flipflop assignments:

$F_{1}$	$F_{0}$
0	0	Down
0	1	Lifting
1	0	Up
1	1	Lowering
Truth table for the state logic:

State ( $F_{1} F_{0}$ )	Input ( $A V B$ )	Next State ( $n e x t F_{1} n e x t F_{0}$ )
00	0XX	00
00	10X	00
00	11X	01
01	0XX	11
01	1X0	01
01	1X1	10
10	1XX	10
10	0XX	11
11	0X0	11
11	1XX	01
11	0X1	00
Truth table for the output logic