University Of Texas At El Paso Electrical And Computer Engin

University Of Texas At El Pasoelectrical And Computer Engineering Depa

University of Texas at El Paso Electrical and Computer Engineering Department EE 2169 –Laboratory for Digital Systems Design I Lab Final – Algorithmic State Machine – The Burrito Vending Machine Due Dates Prelab: 7/3/2017 Demonstration 7/6/2017 Design Package: 7/9/2017 1:00 pm You are tasked with designing the digital system of a burrito vending machine. The vending machine will be rolled out all over UTEP campus by the beginning of the 2018 Fall term, so the design package (which should contain your ASM chart, Verilog module (.V), user constraints (.UCF), programing (.BIT) files, team members, and conclusions) is due by Sunday, July 6 at 1:00 pm. The vending machine is designed to hold three different types of burritos: Bean, Steak, and Chicken. It only accepts US coin denominations of 5, 10, and 25 cents. The price of each burrito is based on your student ID number but has to be a multiple of 5 (you may round to nearest power of 5 achieve this restriction). For Example, if a student engineer has the ID number, the bean burrito should be priced at $0.20, the chicken burrito at $0.50 and the steak burrito at $0.90. The steak burrito should be the most expensive of the three. The bean burrito should be the cheapest. You may decide the prices based on your student ID in the report document and use them as constants when describing the system. Design the vending machine so that it displays the balance on the two seven-segment displays at all times. When initially programed or reset; the machine should have a “00” balance. Assign the buttons on the DFEB as follows. BTN3 = $0.05 inserted BTN2 = $0.10 inserted BTN1 = $0.25 inserted BTN0 = reset machine. Use the switches to choose each burrito as follows: SW7 = Bean Burrito SW6 = Chicken Burrito SW5 = Steak Burrito. When vending: All the LEDs (LD7 through LD0) should turn on and the seven-segment display should show which burrito it is vending. Use “BB” for Bean, “CB” for chicken, and “SB” for steak. After one clock pulse the vending machine should go back to the initial “00” state and wait for the next customer. A few notes on the implementation: 1. Assume that only one button or switch can and will be pressed at a time. No need to account for multiple inputs being on. 2. Assume you will not insert more than $1.00 in coins. 3. If amount of money inserted is not greater than or equal the price of the selected burrito, no action is required from the vending machine. Feel free, however to include some kind of indication that there’s not enough money in the vending machine to buy a particular burrito. 4. Use the CLK signal with (1Hz) frequency as your synchronizing clock. Pre-Lab Draw the Algorithmic State Machine (ASM) chart that describes your design for the burrito vending machine. This is YOUR design, there’s no right or wrong answer, just the one that works correctly. Draw the ASM chart completely as possible, reference chapter 8 in Mano & Ciletti. Lab Email your design package as a compressed folder (.zip) to [email protected] by Sunday Jul 6, 1:00 pm. Name the folder as follows: EE2169_Lastname_Firstname. Your design package should include the following files: ASM Chart in PDF or Word format Verilog module (.v) User Constrains file (.ucf) FPGA Programing file (.bit) Names of the team members. Notes & Conclusions.  You are encouraged to work in teams. Each team may consist of 2 and only 2 students.  If the working vending machine is demonstrated by July 5th a 10% extra credit will be assign to the burrito machine grade.  If the design package is turned in after the due date, a deduction to the burrito machine grade will be made.

Paper For Above instruction

Introduction

The development of a digital vending machine for burritos involves creating a reliable, efficient, and user-friendly system that accurately processes coin inputs, manages selections, and dispenses the desired product according to predefined prices. This paper details the design process, including the creation of an Algorithmic State Machine (ASM) chart, hardware description in Verilog, and implementation considerations to fulfill the requirements specified by the University of Texas at El Paso’s Electrical and Computer Engineering Department.

Design Specifications and Constraints

The vending machine is designed to offer three types of burritos: Bean, Steak, and Chicken, with respective prices determined based on a student’s ID number, rounded to the nearest multiple of 5 cents. The machine accepts US coins of 5, 10, and 25 cents, with the total inserted amount displayed on a pair of seven-segment displays constantly. Initial state resets the balance to “00,” and the system employs specific button inputs for coin insertion and resetting, with switches indicating the burrito choice.

The hardware must ensure only one input is active at a time, simplifying input processing. The machine must prevent vending if the current balance is insufficient relative to the selected burrito's price, without providing change. Additionally, LEDs and the display indicate the vending status, with specific symbols for each burrito type when vending.

System Components and Operation

The core components include:

- Coin inputs via buttons BTN3 (5 cents), BTN2 (10 cents), BTN1 (25 cents),

- Reset button BTN0,

- Switches SW7, SW6, SW5 for burrito selection,

- LEDs LD7-LD0 for status indication,

- Two seven-segment displays for balance display,

- ASM chart illustrating the states from initial reset, coin insertion, selection, to vending and reset.

The system updates the displayed balance corresponding to inserted coins, ensuring the total does not exceed $1.00. When the user selects a burrito, the system checks if the balance covers the price; if so, it activates LEDs and displays the burrito label before returning to the initial state.

Design Methodology: ASM Chart and Verilog Implementation

The ASM chart models the system’s states and transitions based on user inputs and internal conditions, following Mano & Ciletti’s principles. Starting from the reset state, the system transitions to a waiting for input state, then to coin acceptance, selection verification, vending, and returning to the initial state. Each transition is triggered by coin button presses, burrito switch states, or the reset button.

Implementing the system in Verilog involves defining:

- Input and output ports for buttons, switches, LEDs, and displays,

- A finite state machine (FSM) following the ASM chart,

- Registers for holding balance and state,

- Logic for updating balance, managing selections, and vending operations.

System Implementation Details

The Verilog module manages inputs with debouncing considerations, processes coin insertion, updates the balance, handles burrito selection, and controls the outputs for LEDs and displays. The system uses a 1Hz clock signal to synchronize state transitions and counter updates, ensuring timing consistency.

The seven-segment displays show the current balance in decimal format, with display decoding modules converting binary to the appropriate segments. When vending, the system displays corresponding labels: “BB” for Bean, “CB” for Chicken, “SB” for Steak, using a custom display logic.

Conclusion

Developing a burrito vending machine with a verified ASM chart and a comprehensive hardware implementation involves integrating multiple digital design components that fulfill operational requirements. The design ensures accurate coin handling, seamless burrito selection, and clear user feedback through LEDs and displays. Future enhancements could include change dispensing, a more robust user interface, or energy optimization.

References

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