Objectives
â— To design a Vending Machine FSM that takes input of different coins and outputs different items, as directed by an end user.
â— To fully simulate the Vending Machine, walking through all possible combinations of states, inputs and outputs. The end goal is a design that could be placed on the Basys3 board, though that will not be required for a grade in this project.

Introduction
The Vending Machine will be capable of taking three different coin inputs: a Nickel, Dime, and a Quarter. Three items will be available for user selection and dispensing: Gum ($0.15), Apple ($0.25), and Pretzels ($0.30). A â€œReturn Changeâ€ option should be available to the user to cancel their attempt and return their funds. The 7-Segment LED Displays and on-board LEDâ€™s will be used for user feedback. While usage of the Basys3 board will not be required, you should develop your system under the assumption that it could be placed on the board.
Your design should incorporate the following inputs:
â€¢ Switch-0: Nickel input
â€¢ Switch-1: Dime input
â€¢ Switch-2: Quarter input
â€¢ BTNL: Gum selection
â€¢ BTNC: Apple selection
â€¢ BTNR: Pretzel selection
â€¢ BTNU: System Reset
â€¢ BTND: Change Return
Your design should utilize the following outputs:
â€¢ 7-Segment LED Leftmost 2 Displays: Current amount deposited
â€¢ 7-Segment LED Rightmost 2 Displays: User Selection/Error Feedback
â€¢ LED0: Nickel Return (change request)
â€¢ LED1: Dime Return (change request)
â€¢ LED2: Quarter Return (change request)

Part I â€“ Vending Machine Finite State Machines
The overall Vending Machine FSM will be composed of FSMâ€™s to tackle specific tasks. Part 1 is to plan out your
design for this project before actually putting together any Verilog.
1. Fund Maintenance: Design an FSM for keeping track of the amount of money that the user has inserted. Since the most expensive item available is $0.30, you can stop accepting money beyond that point. The change/refund process will be another FSM so donâ€™t worry about that here, however, you should allow reset functionality to clear the funds in the event of a fresh launch, refund request, or purchase.
2. Coin Return: Design an FSM for returning coins one at a time in the event of a refund or a purchase where change is necessary. The coin return will need to take input of the amount to return, then loop through illuminating the Quarter LED, Dime LED, or Nickel LED, each coin separated by 4 clock cycles, until all funds have been dispensed. Put some thought into how you want this process to begin and end.
3. Purchase Selection: Design an FSM for handling a purchase when the user makes an item selection. This FSM should validate that the user has enough money for the chosen item and should display either the selected item or an error message on the 7-Segment Displays for 2 clock cycles. This FSM should then indicate how much change is to be returned by the Coin Return FSM based on the selection made and amount of money currently in the system.
4. Vending Machine: Design your overall FSM that will link all sub-FSMâ€™s together, adding any other modules/FSMâ€™s that you deem necessary to make one cohesive Vending Machine project. Your Vending Machine is responsible for monitoring user inputs of money {5Â¢,10Â¢,25Â¢}, commands {Reset, Refund}, and item selections {Gum, Apple, Pretzels}, then updating user feedback appropriately for current funds {00Â¢ through 30Â¢}, item dispenses {Gu, AP, Pr}, error messages {Lo}, and coin returns {Nickel-LED, Dime-LED, Quarter-LED}. Timing between displays is given in terms of real-time (seconds) but can be sped up significantly for the sake of simulation.

Part II â€“ Updated 7-Segment Decoder
The 7-Segment Display will need to be able to display a variety of new characters, therefore, a rework is required for the decoder module we have used in the past labs.
1. Modify your 7-Segment Decoder to take an 8-bit vector (1-byte) as input instead of the 4-bit vector (1-nibble) previously used.
2. Add additional decoding cases for ASCII inputs: â€˜Gâ€™, â€˜uâ€™, â€˜Aâ€™, â€˜Pâ€™, â€˜râ€™, â€˜Lâ€™ and â€˜oâ€™
a. Pay attention to the provided upper/lower casing, these are provided to make the most sense of the 7-segment display when showing these particular letters.
3. Add one final case for turning the display completely off (all segments set to 1). This will be necessary in a few instances of the vending machine operation.
4. Create a testbench for your 7-Segment Decoder that runs through all possible input combinations.
5. Use a Verilog Task in your testbench to validate that the output segments are illuminated as expected, instead of looking at a large simulation window of 1â€™s and 0â€™s. Your Task should take input of the expected segments (7-bits) and print feedback that indicates if the segments match expected values or not

Part III â€“ Fund Maintenance
1. Implement your FSM for maintaining funds in your Vending Machine as a module.
2. Create a testbench that walks through different permutations of coin entry to ensure that your fund maintenance module functions properly. Funds should be incremented only once per coin input, should be capped at 30cents, and should be easily cleared to 0 as needed.

Part IV â€“ Coin Return
1. Implement your FSM for returning coins in your Vending Machine as a module.
2. Create a testbench that validates coins are returned in the most efficient way possible for all 5cent increments of 0cents to 30cents. For example, if a coin return is initiated with 15cents as the amount, your module should output a dime and a nickel, separated by a clock cycle. Once all coins are dispensed, the coin-LEDs should be turned of to indicate no coins are continuously flying out of your Vending Machine.

Part V â€“ Purchase Selection
1. Implement your FSM for making a purchase selection in your Vending Machine as a module.
2. Create a testbench that demonstrates the purchase selector can correctly decipher sufficient/insufficient funds for a purchase, update the User Feedback 7-Segment Displays appropriately with selection or error messages, and output a correct amount of change for the Coin Return module. Once the 2 seconds of expected display time are complete, the User Feedback 7-Segment Displays should be turned off to indicate the machine is ready for a new user.

Part VI â€“ Final Vending Machine
1. Connect all the pieces of your vending machine into one final Top module.
2. Create one final testbench that walks through a few sample uses of your Vending Machine. This demonstration should include (at least), example coin entry, example refund requests, and example purchases, both successful and unsuccessful ones due to current funds.
3. Because there will be a large number of inputs/outputs, it will be important to take advantage of Verilog Tasks in this testbench instead of trying to monitor the simulation window and make sense of all the waveforms.

Objectives â— To design a Vending Machine FSM that takes input o...

Objectives â— To design a Vending Machine FSM that takes input o...