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

📅 By Dinesh | Tech DIY Projects | May 2025

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🚀 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!

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🧠 Project Concept

Here’s how the system works:

1. User scans an RFID card.

2. Arduino detects the card, plays a welcome sound using DFPlayer, and sends the name to ESP32.

3. ESP32 receives the name via serial and logs it to a Google Sheet using a webhook.

4. Done! The name and timestamp are saved in the cloud.

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🧰 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

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🔌 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.

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📟 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!");
    }
  }
}

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🎉 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 🌐.

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❤️ Let’s Connect

Have doubts or want to build your own version?

📧 Contact me on: dtrendchannel@gmail.com

🌞 DIY Arduino Solar Tracker with Motor Control – Complete Guide

 

🌞 DIY Arduino Solar Tracker with Motor Control – Complete Guide

🔧 Overview:

This project uses Light Dependent Resistors (LDRs) to track the sun's position and adjust the orientation of a solar panel using two servo motors. Additionally, based on the sunlight intensity, it controls a motor using two buttons – ideal for automating a solar-powered device like a water pump.

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🧰 Components Required:

Component	Quantity	Description
Arduino Uno	1	Microcontroller board
Servo Motor (SG90/MG90)	2	For horizontal and vertical rotation
LDR (Light Sensor)	5	For detecting sunlight intensity and direction
10kΩ Resistors	5	Pull-down resistors for each LDR
Push Buttons	2	For controlling motor direction
DC Motor	1	Can be used for pumping or rotation purposes
NPN Transistor (optional)	1	For driving higher power motors
Diode (1N4007)	1	For back EMF protection
Power Supply (9V/12V)	1	To power the motor
Breadboard + Jumper Wires	As needed	For circuit connections

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🔌 Pin Configuration:

Arduino Pin	Connected Component
A1	LDR Top Left
A2	LDR Top Right
A3	LDR Bottom Left
A4	LDR Bottom Right
A5	LDR Middle Top (Sunlight Detection)
D5	Horizontal Servo Signal
D6	Vertical Servo Signal
D7	Motor Control A
D8	Motor Control B
D9	Button 1 (Forward)
D10	Button 2 (Reverse)
GND	All GND connections
5V	Power supply for LDRs and buttons

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⚙️ How It Works:

• LDRs detect light intensity. The 4 corner LDRs determine the direction of sunlight, and the middle LDR checks whether there is enough light.

• The Arduino calculates the average light values and adjusts the horizontal and vertical servo angles accordingly.

• If sunlight is detected and button 1 is pressed, the motor rotates in one direction.

• If no sunlight is present and button 2 is pressed, the motor rotates in the opposite direction.

• If neither condition is met, the motor stops.

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🖼️ Circuit Diagram:

📟 Arduino Code:

#include <Servo.h>

Servo horizontal; // horizontal servo

Servo vertical; // vertical servo
// LDR analog pins
const int button1 = 9;
int pos = 0;
void setup() {
  pinMode(motorA, OUTPUT);
  delay(2500); // Give servos time to initialize
void loop() {
    int lt = analogRead(ldrlt);
    int avt = (lt + rt) / 2;
    if (abs(dvert) > tol) {
    if (abs(dhoriz) > tol) {
    delay(dtime);
    for (pos = oldvalue; pos <= 180; pos++) {
    buttonStateB = digitalRead(button2);

int servoh = 180;

int servohLimitHigh = 175;

int servohLimitLow = 5;

int servov = 0;

int servovLimitHigh = 60;

int servovLimitLow = 0;

int ldrlt = A1; // Top Left

int ldrrt = A2; // Top Right

int ldrld = A3; // Bottom Left

int ldrrd = A4; // Bottom Right

int ldrmt = A5; // Middle Top LDR

const int button2 = 10;

const int motorA = 7;

const int motorB = 8;

int buttonStateA = 0;

int buttonStateB = 0;

int pos2 = 0;

int oldvalue, oldvalue2;

  horizontal.attach(5);

  vertical.attach(6);

  horizontal.write(180);

  vertical.write(0);

  pinMode(motorB, OUTPUT);

  pinMode(button1, INPUT);

  pinMode(button2, INPUT);

}

  int ldrStatus = analogRead(ldrmt);

  

  if (ldrStatus > 30) {

    buttonStateA = digitalRead(button1);

    if (buttonStateA == LOW) {

      digitalWrite(motorA, HIGH);

      digitalWrite(motorB, LOW); // Motor rotates in one direction

    } else {

      digitalWrite(motorA, LOW);

      digitalWrite(motorB, LOW); // Stop motor

    }

    int rt = analogRead(ldrrt);

    int ld = analogRead(ldrld);

    int rd = analogRead(ldrrd);

    int dtime = 10;

    int tol = 90;

    int avd = (ld + rd) / 2;

    int avl = (lt + ld) / 2;

    int avr = (rt + rd) / 2;

    int dvert = avt - avd;

    int dhoriz = avl - avr;

      if (avt > avd) {

        servov++;

        if (servov > servovLimitHigh) servov = servovLimitHigh;

      } else {

        servov--;

        if (servov < servovLimitLow) servov = servovLimitLow;

      }

      vertical.write(servov);

    }

      if (avl > avr) {

        servoh--;

        if (servoh < servohLimitLow) servoh = servohLimitLow;

      } else {

        servoh++;

        if (servoh > servohLimitHigh) servoh = servohLimitHigh;

      }

      horizontal.write(servoh);

    }

  }

  else {

    oldvalue = horizontal.read();

    oldvalue2 = vertical.read();

      horizontal.write(pos);

      delay(15);

    }

    for (pos2 = oldvalue2; pos2 >= 0; pos2--) {

      vertical.write(pos2);

      delay(15);

    }

    if (buttonStateB == LOW) {

      digitalWrite(motorA, LOW);

      digitalWrite(motorB, HIGH); // Reverse motor

    } else {

      digitalWrite(motorA, LOW);

      digitalWrite(motorB, LOW);

    }

  }

}

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