📚 RFID-Based Access Control System using ESP8266

A secure and IoT-enabled RFID access control system that uses the ESP8266 microcontroller, RC522 RFID reader, and Google Sheets API to log access entries (name, date, time) in real time. Designed for libraries but easily scalable for offices, hostels, labs, and smart campuses.

---

🚀 Features

• ✅ Secure user authentication using RFID (RC522)
• 📟 Real-time feedback on 16x2 LCD
• 🔊 Buzzer alerts for granted or denied access
• 🌐 Wi-Fi-enabled logging using ESP8266
• ☁️ Data automatically logged to Google Sheets (cloud-based)
• 📈 Logs name, date, and time of each access attempt
• 🔒 Works only for pre-authorized users

---

🛠️ Tech Stack

• Microcontroller: ESP8266 (NodeMCU)
• Sensors: RC522 RFID reader, buzzer, 16x2 I2C LCD
• Programming: C/C++ (Arduino IDE)
• Cloud Integration: Google Sheets API (via Apps Script)
• Libraries Used:
  • MFRC522.h – RFID reader
  • ESP8266WiFi.h – Wi-Fi connection
  • WiFiClientSecure.h – HTTPS for Google Sheets
  • LiquidCrystal_I2C.h – LCD display

---

🖼️ System Architecture

[RFID Card] --> [RC522 Reader] --> [ESP8266]
                                         |
                               [Authorization Check]
                                         |
                             +-----------+-----------+
                             |                       |
                      [Access Granted]        [Access Denied]
                             |                       |
              [Display on LCD + Buzzer]      [Display on LCD + Buzzer]
                             |
                [Log to Google Sheet via Wi-Fi]