Mealy Tollgate FSM

module TollGateFSM (
  input wire vehicleApproaches,
  input wire rfidDetected,
  input wire sufficientBalance,
  output reg vehiclePasses,
  output reg gateOpen,
  output reg tollCollected
);

  // Enumerated states
  `define Closed 2'b00
  `define Open   2'b01
  `define Error  2'b10
  parameter Closed = 2'b00;
  parameter Open   = 2'b01;
  parameter Error  = 2'b10;

  // State register and next state logic
  reg [1:0] currentState, nextState;

  // Initial state assignment
  initial begin
    currentState = Closed;
    nextState = Closed;
    gateOpen = 0;
    tollCollected = 0;
  end

  always @(posedge vehicleApproaches or posedge rfidDetected or posedge sufficientBalance) begin
    case (currentState)
      Closed:
        if (rfidDetected && sufficientBalance && vehicleApproaches) begin
          nextState <= Open;
          vehiclePasses <= 1;
          gateOpen <= 1;  // Open the gate when transitioning to Open state
          tollCollected <= 1;  // Collect toll when transitioning to Open state
        end
        else if (rfidDetected && !sufficientBalance && vehicleApproaches) begin
          nextState <= Closed;
          vehiclePasses <= 0;
          gateOpen <= 0;
          tollCollected <= 0;
        end
        else if (!rfidDetected && vehicleApproaches) begin
          nextState <= Closed;
          vehiclePasses <= 0;
          gateOpen <= 0;
          tollCollected <= 0;
        end
        else begin
          nextState <= Error;
        end
      Open:
        if (vehiclePasses) begin
          nextState <= Closed;
          gateOpen <= 0;
          tollCollected <= 0;
        end
        else begin
          nextState <= Open;
        end

      Error:
        nextState <= Error;
    endcase
  end

  // State update
  always @(posedge vehicleApproaches or posedge rfidDetected or posedge sufficientBalance) begin
    if (currentState != nextState) begin
      currentState <= nextState;
    end
  end

endmodule