Question

A customer want’s a vending machine that will accept Nickel and Dime and dispense gum or candy. The gum pack cost 20₵ and the candy cost 15₵. When the user enters a coin in the slot it should decode the type of coin that has been entered and will displayed the total amount enter thus far in a seven segment display. If that amount is less than the item cost the system will tell the user that they have insufficient funds to make such purchase. A keypad is available to the user in order to select the item they wish to purchase. The keypad has three buttons in the following order button 1(Candy), button 2(Gum), button 3(coin return). In the process of selecting an item, if the user decides to change their mind they have the option of canceling the transaction and subsequently will return the amount they have inputted thus far. If for somehow the user needs change back, it will only be given back in nickels and up to 15₵. When an item is dispense LED 1( Gum) or LED 2( Candy) should turn on.

Just need FSM