`timescale 1ns / 1ps
//////////////////////////////////////////////////////////////////////////////////
// Company:
// Engineer:
//
// Create Date:    12:48:23 01/28/2020
// Design Name:
// Module Name:    coin
// Project Name:
// Target Devices:
// Tool versions:
// Description:
//
// Dependencies:
//
// Revision:
// Revision 0.01 - File Created
// Additional Comments:
//
//////////////////////////////////////////////////////////////////////////////////
module coin( input fifty, dollar, cancel, clk, rst,
  output reg insert_coin, money_return, dispense, output reg [1:0] st
);

parameter INIT=0,S50c=1,VEND=2,RETURN=3;

reg [1:0] nst;

always @ (posedge clk)
begin
  if(~rst)
    st <= INIT;
  else
    st <= nst;
end

always @*
begin
  nst = st;
  insert_coin = 1; money_return = 0; dispense = 0;
  case(st)
    INIT: begin
		if(fifty)nst = S50c;
		if(dollar) nst = VEND;
    end
    S50c: begin
		if(fifty) nst = VEND;
		if(dollar) nst = RETURN;
		if(cancel) nst = RETURN;
    end
    VEND: begin
		insert_coin = 0; money_return = 0; dispense = 1;
    end
    RETURN: begin
		insert_coin = 0; money_return = 1; dispense = 0;
      nst = INIT;
	 end
  endcase
end

endmodule