This project involves designing a coffee vending machine controlled by an Arduino UNO. The machine allows users to select a coffee type and size, make payments, and receive coffee through an automated dispensing system controlled by a servo motor. An I2C LCD displays the operation status, and LEDs provide visual feedback.

Components used in Coffee Vending Machine:

1. Arduino UNO – Main microcontroller to control all operations.
2. Servo Motor – Dispenses the coffee by controlling a valve or opening a chute.
3. I2C LCD Display (16×2) – Displays user selections and payment details.
4. Push Button (Enter Button) – Used to confirm selections and proceed with payment.
5. Sliding Potentiometer – Selects the coffee type.
6. DIP Switch – Sets the coffee cup size.
7. LEDs – Indicate machine status (e.g., selection made, payment required, dispensing).
8. Additional Push Buttons – Used to increment the payment amount.
9. Buzzer (Optional) – Provides an audible alert when coffee is ready.

Working of Coffee Vending Machine:

. User Selection Process

• The user adjusts the sliding potentiometer to select one of the four coffee types:
  • MILD
  • BOLD
  • STRONG
  • FULL
• The selected coffee type is displayed on the I2C LCD.
• The user then sets the coffee size using the DIP switch settings:
  • Small (100ml)
  • Medium (200ml)
  • Large (300ml)
• The size selection is also displayed on the LCD.
• The user confirms the selection by pressing the ENTER button.

2. Payment System

• The machine requires payment before dispensing coffee.
• The user pays using incremental push buttons:
  • Each button press adds a fixed amount (e.g., $0.50 per press).
  • The LCD displays the total amount inserted.
• If the inserted amount is less than the required price, the LCD prompts the user to add more money.
• If the exact amount is entered, the system proceeds to dispensing.
• If the user overpays, the extra amount is refunded automatically.

3. Coffee Dispensing Process

• Once full payment is received:
  • The LED indicator turns GREEN.
  • The servo motor activates and opens the coffee dispensing valve.
  • The machine pours the selected coffee type and amount into the cup.
• After dispensing is complete:
  • A message is displayed on the LCD confirming the process.
  • The buzzer (if used) sounds to indicate that coffee is ready.
  • The LED blinks to signal completion.

4. Refund Mechanism

• If an excess amount is inserted, the system calculates the difference.
• The LCD displays the refund amount, and the system either:
  • Returns the extra amount (if a coin return mechanism is implemented).
  • Gives the user an option for additional purchases.

Circuit Diagram of Coffee Vending Machine:

Code for Coffee Vending Machine Project:

#include <Wire.h>
#include <LiquidCrystal_I2C.h>
#include <Servo.h>

//LiquidCrystal_I2C lcd(0x27, 16, 2);  // I2C LCD object
LiquidCrystal_I2C lcd(32, 16, 2);  // I2C LCD object

Servo servo;                        // Servo motor object

const int potentiometerPin = A0;    // Potentiometer pin
const int buttonPin = 2;            // Push button pin
const int dipSwitchPin1 = 11;       // DIP switch pin 2
const int dipSwitchPin2 = 10;       // DIP switch pin 1
const int dipSwitchPin3 = 13;       // DIP switch pin 4
const int dipSwitchPin4 = 12;       // DIP switch pin 3
const int ledPin = 4;               // LED pin

const int regularAngle = 45;        // Servo angle for Regular coffee
const int espressoAngle = 90;       // Servo angle for Espresso coffee
const int cappuccinoAngle = 135;    // Servo angle for Cappuccino coffee
const int latteAngle = 180;         // Servo angle for Latte coffee

const int regularPrice = 16;        // Price for Regular coffee (in DKK)
const int espressoPrice = 19;       // Price for Espresso coffee (in DKK)
const int cappuccinoPrice = 25;     // Price for Cappuccino coffee (in DKK)
const int lattePrice = 50;          // Price for Latte coffee (in DKK)

int selectedCoffee = 0;             // Selected coffee type (0: None, 1: MILD, 2: BOLD, 3: STRONG, 4: FULL)
int selectedProduct = 0;            // Selected coffee product (0: Regular, 1: Espresso, 2: Cappuccino, 3: Latte)
int selectedCoins = 0;              // Selected coins (in DKK)
int price=0; 
bool flag=true;
String flavor="";

void setup() {
  lcd.begin();                 // Initialize LCD
  //lcd.init(16, 2);

  // lcd.begin(16, 2);                 // Initialize LCD
  // lcd.init();


  lcd.backlight();                  // Turn on LCD backlight

  servo.attach(3);                  // Attach servo to pin 9

  pinMode(buttonPin, INPUT_PULLUP);
  pinMode(dipSwitchPin1, INPUT_PULLUP);
  pinMode(dipSwitchPin2, INPUT_PULLUP);
  pinMode(dipSwitchPin3, INPUT_PULLUP);
  pinMode(dipSwitchPin4, INPUT_PULLUP);
  pinMode(ledPin, OUTPUT);

  lcd.print("Coffee Machine");      // Display initial message on LCD
  lcd.setCursor(0, 1);
  lcd.print("Press Enter");
}

Working Video of Coffee Vending Machine:

Applications of Coffee Vending Machine:

The coffee vending machine has several practical applications, including:

• Offices and Workplaces – Provides a quick and automated way for employees to get coffee without needing a barista.
• Universities and Colleges – Enables students and faculty to get coffee conveniently.
• Shopping Malls and Public Spaces – Serves customers in high-traffic areas with minimal supervision.
• Hospitals and Clinics – Provides coffee for patients and staff in waiting areas.
• Transportation Hubs – Airports, train stations, and bus terminals can use vending machines for travelers in need of refreshment.
• Hotels and Restaurants – Offers a self-service coffee option to guests.
• Events and Conferences – Provides an efficient coffee distribution method for large gatherings.

Conclusion:

This project provides an interactive, automated coffee vending machine with user-friendly operation. By using an Arduino UNO, servo motor, LCD display, push buttons, and a potentiometer, the system efficiently manages coffee selection, payment, and dispensing. The refund mechanism ensures a smooth experience for users, making it a practical implementation of embedded systems in vending machines.

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