🎯 Build Your Own RFID Attendance System Using Arduino + ESP32 + Google Sheets

📅 By Dinesh | Tech DIY Projects | May 2025

🚀 Introduction

Have you ever wanted to build a smart attendance system that logs student or staff attendance directly into Google Sheets in real time?

In this tutorial, I’ll show you how I created a WiFi-connected RFID attendance system using:

✅ Arduino UNO (for RFID + DFPlayer)
✅ ESP32 (for WiFi + Google Sheet logging)
✅ Google Apps Script (to act as a cloud database)

Let’s dive in!

🧠 Project Concept

Here’s how the system works:

User scans an RFID card.
Arduino detects the card, plays a welcome sound using DFPlayer, and sends the name to ESP32.
ESP32 receives the name via serial and logs it to a Google Sheet using a webhook.
Done! The name and timestamp are saved in the cloud.

🧰 Components Used

Component	Quantity
Arduino UNO	1
ESP32 (DevKit v1)	1
MFRC522 RFID Reader	1
RFID Tags/Cards	2+
DFPlayer Mini + Speaker	1
I2C LCD 16x2 Display	1
Jumper Wires	-
Voltage Regulator (if needed for 3.3V logic level)	1
Breadboard	1

🔌 Connections

RFID & DFPlayer to Arduino UNO:

RFID SDA → D10
RFID RST → D9
DFPlayer TX → D4
DFPlayer RX → D5
LCD I2C → A4 (SDA), A5 (SCL)

Arduino to ESP32:

Arduino TX (D1) → ESP32 RX (GPIO 16)
IMPORTANT: Use voltage divider or level shifter to avoid 5V-to-3.3V damage to ESP32.

📟 Arduino Code

The Arduino reads the card, displays info, and plays sound:

cpp

#include <Wire.h>
#include <LiquidCrystal_I2C.h>
#include <SoftwareSerial.h>
#include <DFRobotDFPlayerMini.h>
#include <SPI.h>
#include <MFRC522.h>

// LCD I2C
LiquidCrystal_I2C lcd(0x27, 16, 2); // Adjust address if needed

// DFPlayer Mini on pins 4 (RX), 5 (TX) Arduino side
SoftwareSerial dfSerial(4, 5);
DFRobotDFPlayerMini myDFPlayer;

// RFID pins
#define RST_PIN 9
#define SS_PIN 10
MFRC522 rfid(SS_PIN, RST_PIN);

// DFPlayer Reset pin (optional)
#define DFPLAYER_RESET_PIN 8

// Known RFID UIDs and names
String knownUIDs[] = {
  "EA514D63"
};
String names[] = {
  "Dinesh"
};

// Retry DFPlayer initialization
bool initDFPlayer() {
  for (int i = 0; i < 5; i++) {
    if (myDFPlayer.begin(dfSerial)) {
      return true;
    }
    delay(1000); // Wait 1 sec before retry
  }
  return false;
}

void setup() {
  delay(3000); // Let power stabilize

  pinMode(DFPLAYER_RESET_PIN, OUTPUT);
  digitalWrite(DFPLAYER_RESET_PIN, LOW);  // Hold DFPlayer in reset
  delay(100);  // Reset pulse
  digitalWrite(DFPLAYER_RESET_PIN, HIGH); // Release reset
  delay(1000); // Wait for DFPlayer to boot

  Serial.begin(9600);   // Serial to ESP32
  dfSerial.begin(9600); // DFPlayer serial
  SPI.begin();
  rfid.PCD_Init();

  lcd.init();
  lcd.backlight();
  lcd.setCursor(0, 0);
  lcd.print("Scan your ID...");

  if (!initDFPlayer()) {
    lcd.setCursor(0, 1);
    lcd.print("DFPlayer Error");
    Serial.println("Unable to initialize DFPlayer Mini!");
    while (true); // Halt
  }

  myDFPlayer.volume(30); // Set volume (0-30)
}

void loop() {
  if (!rfid.PICC_IsNewCardPresent() || !rfid.PICC_ReadCardSerial()) {
    return;
  }

  // Read UID and convert to uppercase hex string
  String uid = "";
  for (byte i = 0; i < rfid.uid.size; i++) {
    if (rfid.uid.uidByte[i] < 0x10) uid += "0";
    uid += String(rfid.uid.uidByte[i], HEX);
  }
  uid.toUpperCase();
  Serial.println("UID: " + uid);

  bool matchFound = false;
  for (int i = 0; i < 6; i++) {
    if (uid == knownUIDs[i]) {
      lcd.clear();
      lcd.setCursor(0, 0);
      lcd.print("Welcome,");
      lcd.setCursor(0, 1);
      lcd.print(names[i]);
      Serial.println("Attendance marked for " + names[i]);

      // Send matched UID and name to ESP32
      Serial.print("MATCH:");
      Serial.print(uid);
      Serial.print(",");
      Serial.println(names[i]);

      myDFPlayer.play(1); // Play welcome sound
      matchFound = true;
      break;
    }
  }

  if (!matchFound) {
    lcd.clear();
    lcd.setCursor(0, 0);
    lcd.print("Unknown card");
    Serial.println("Unknown UID");

    // Send unknown info to ESP32
    Serial.println("UNKNOWN");

    myDFPlayer.play(2); // Play error sound (optional)
  }

  delay(3000); // Wait before next scan
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Scan your ID...");
}

📡 ESP32 Code (Receives & Sends to Google Sheet)

cpp
#include <WiFi.h>
#include <HTTPClient.h>

#define RXD2 16  // Arduino TX to ESP32 RX
#define TXD2 17  // Not used, but required for Serial2 init

const char* ssid = "*****";         // 🔁 Replace with your WiFi SSID
const char* password = "****";       // 🔁 Replace with your WiFi password

const char* serverName = "*****";     // 🔁 Replace with excelsheet link

void setup() {
  Serial.begin(115200);
  Serial2.begin(9600, SERIAL_8N1, RXD2, TXD2);  // Serial2 from Arduino

  Serial.println("Connecting to WiFi...");
  WiFi.begin(ssid, password);
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }

  Serial.println("\nWiFi connected!");
}

void loop() {
  if (Serial2.available()) {
    String name = Serial2.readStringUntil('\n');
    name.trim(); // Remove leading/trailing whitespace

    Serial.println("Received from Arduino: " + name);

    // Remove "MATCH:" prefix if present
    if (name.startsWith("MATCH:")) {
      name = name.substring(6);
    }

    // Remove everything before the first comma, including the comma
    int commaIndex = name.indexOf(',');
    if (commaIndex != -1) {
      name = name.substring(commaIndex + 1);
    }

    Serial.println("Cleaned name: " + name);

    if (WiFi.status() == WL_CONNECTED) {
      HTTPClient http;

      String url = String(serverName) + name;
      http.begin(url);
      int httpResponseCode = http.GET();

      if (httpResponseCode > 0) {
        Serial.println("Data sent to Google Sheet!");
      } else {
        Serial.print("Error sending data: ");
        Serial.println(httpResponseCode);
      }

      http.end();
    } else {
      Serial.println("WiFi disconnected!");
    }
  }
}

🎉 Final Result

✅ RFID card scanned
✅ Welcome message on LCD
✅ Sound plays via DFPlayer
✅ Name logged in Google Sheet

No need for SD cards or Excel files — everything is real-time in the cloud 🌐.

❤️ Let’s Connect

Have doubts or want to build your own version?

📧 Contact me on: dtrendchannel@gmail.com

D Trend

Friday, 23 May 2025