How to build an ESP32-based electronic voting system

📖 Course Overview

🔌 Components & Wiring Guide

🛠️ Step-by-Step Tutorial

💻 Sample Code

#include <Arduino.h>
#include <MFRC522.h>
#include <Wire.h>
#include <LiquidCrystal_I2C.h>
#include <Adafruit_Fingerprint.h'

// Define pins for RFID module
#define RST_PIN 22
#define SS_PIN  5

// Define pins for push buttons
#define BUTTON1_PIN 13
#define BUTTON2_PIN 12
#define BUTTON3_PIN 14
#define BUTTON4_PIN 27

// Define pins for fingerprint sensor
#define FINGERPRINT_TX_PIN 17
#define FINGERPRINT_RX_PIN 16

// Define pins for buzzer
#define BUZZER_PIN 25

// Define LCD display address
#define LCD_ADDRESS 0x27

MFRC522 mfrc522(SS_PIN, RST_PIN);
LiquidCrystal_I2C lcd(LCD_ADDRESS, 16, 2);
Adafruit_Fingerprint fingerprints = Adafruit_Fingerprint(FINGERPRINT_TX_PIN, FINGERPRINT_RX_PIN);

// Function to initialize RFID module
void initRFID() {
  SPI.begin();
  mfrc522.PCD_Init();
}

// Function to read RFID card
void readRFID() {
  if (!mfrc522.PICC_IsNewCardPresent()) return;
  if (!mfrc522.PICC_ReadCardSerial()) return;
  // Get UID of the card
  byte *uid = mfrc522.uid.uidByte;
  byte uidSize = mfrc522.uid.size;
  // Authenticate the card
  if (uidSize != 4) return;
  byte expectedUID[4] = {0x12, 0x34, 0x56, 0x78}; // Replace with your expected UID
  bool isValid = true;
  for (int i = 0; i < uidSize; i++) {
    if (uid[i] != expectedUID[i]) {
      isValid = false;
      break;
    }
  }
  if (!isValid) return;
  // Start voting process
  lcd.setCursor(0, 0);
  lcd.print("Voting started");
}

// Function to handle push button press
void handleButtonPress(int buttonPin) {
  // Read the state of the button
  int buttonState = digitalRead(buttonPin);
  if (buttonState == HIGH) {
    // Select candidate based on button pressed
    if (buttonPin == BUTTON1_PIN) {
      lcd.setCursor(0, 1);
      lcd.print("Candidate 1");
    } else if (buttonPin == BUTTON2_PIN) {
      lcd.setCursor(0, 1);
      lcd.print("Candidate 2");
    } else if (buttonPin == BUTTON3_PIN) {
      lcd.setCursor(0, 1);
      lcd.print("Candidate 3");
    } else if (buttonPin == BUTTON4_PIN) {
      lcd.setCursor(0, 1);
      lcd.print("Candidate 4");
    }
    // Verify voter's identity using fingerprint sensor
    verifyFingerprint();
  }
}

// Function to verify fingerprint
void verifyFingerprint() {
  // Get fingerprint image
  int fingerprintResult = fingerprints.getImage();
  if (fingerprintResult != FINGERPRINT_OK) {
    lcd.setCursor(0, 1);
    lcd.print("Fingerprint error");
    return;
  }
  // Convert image to template
  fingerprintResult = fingerprints.image2Tz(1);
  if (fingerprintResult != FINGERPRINT_OK) {
    lcd.setCursor(0, 1);
    lcd.print("Fingerprint error");
    return;
  }
  // Compare template with stored template
  fingerprintResult = fingerprints.compareFinger();
  if (fingerprintResult != FINGERPRINT_OK) {
    lcd.setCursor(0, 1);
    lcd.print("Fingerprint error");
    return;
  }
  // If fingerprint matches, record vote
  recordVote();
}

// Function to record vote
void recordVote() {
  // Save vote to database or flash memory
  lcd.setCursor(0, 0);
  lcd.print("Vote recorded");
  // Provide audio feedback
  tone(BUZZER_PIN, 1000, 500);
}

void setup() {
  Serial.begin(115200);
  // Initialize RFID module
  initRFID();
  // Initialize LCD display
  lcd.init();
  lcd.backlight();
  // Initialize fingerprint sensor
  fingerprints.begin(57600);
  if (!fingerprints.verifyPassword()) {
    lcd.setCursor(0, 0);
    lcd.print("Fingerprint sensor error");
    while (true);
  }
  // Initialize push buttons
  pinMode(BUTTON1_PIN, INPUT);
  pinMode(BUTTON2_PIN, INPUT);
  pinMode(BUTTON3_PIN, INPUT);
  pinMode(BUTTON4_PIN, INPUT);
  // Initialize buzzer
  pinMode(BUZZER_PIN, OUTPUT);
}

void loop() {
  // Check for RFID card presence
  readRFID();
  // Check for push button press
  handleButtonPress(BUTTON1_PIN);
  handleButtonPress(BUTTON2_PIN);
  handleButtonPress(BUTTON3_PIN);
  handleButtonPress(BUTTON4_PIN);
  delay(100);
}

📝 Quiz Yourself

1. What is the primary function of the RFID module in the ESP32-based electronic voting system?
   a) To verify the citizen's fingerprint
   b) To display voting instructions and status
   c) To initialize and authenticate the voting session
   d) To provide audio feedback
   Answer: c

2. Which of the following components is responsible for providing audio feedback in the voting system?
   a) I2C LCD Display
   b) Push Buttons
   c) Fingerprint Sensor
   d) Buzzer
   Answer: d

3. What is the purpose of the two-factor authentication in the voting system?
   a) To allow multiple voters to vote at the same time
   b) To verify the voter's identity before recording the vote
   c) To select a candidate
   d) To display voting results
   Answer: b

4. How many push buttons are used in the ESP32-based electronic voting system?
   a) 2
   b) 3
   c) 4
   d) 5
   Answer: c

5. What is the role of the I2C LCD Display in the voting system?
   a) To authenticate the voter using RFID
   b) To verify the voter's fingerprint
   c) To display instructions and voting status
   d) To record the vote
   Answer: c