Access Control System

An ESP32-based RFID access control system featuring real-time validation through a Node.js/Express backend with MongoDB storage.
Includes a configuration portal, 3D-printed enclosure, device display feedback, and complete wireless provisioning.

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Overview

This project implements a complete access control system using:

• ESP32 microcontroller
• MFRC522 RFID reader
• Node.js/Express backend
• MongoDB database
• Custom 3D-printed enclosure
• Wi-Fi configuration portal with onboard AP mode

The device reads RFID cards, sends their UID to the backend server, and reacts with ALLOW or DENY feedback based on server response.

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Features

• ESP32 firmware written for stable, real-time operation
• MFRC522 RFID card reading
• HTTP communication with backend
• Node.js/Express REST API for validation and logging
• MongoDB database for storing authorized cards and access logs
• Device display + buzzer for user feedback
• Wi-Fi provisioning via internal access point
• Web-based configuration UI (both in AP mode and on normal LAN)
• Custom 3D-printed enclosure designed for daily use

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System Architecture

[ RFID Card ] --> [ ESP32 + MFRC522 ] --> HTTP Request --> [ Node.js/Express Backend ] --> [ MongoDB ]
                                          <-- HTTP Response (ALLOW / DENY) <--

• Device reads RFID UID
• Sends UID to backend
• Backend checks database
• Backend sends ALLOW / DENY
• Device displays result + optional buzzer

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Hardware

Components used:

• ESP32 Dev Board
• MFRC522 RFID reader
• Small I2C display (SSD1306 128x64)
• Buzzer
• Reset/config button (accessible through enclosure pinhole)
• Custom 3D-printed enclosure

Enclosure photos and 3D files live in:

./docs/images/
./enclosure/

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Firmware (ESP32)

Located in:

./RFID/

Responsible for:

• Initializing MFRC522 and reading card UIDs
• Connecting to Wi-Fi (STA mode)
• Communicating with the backend via HTTP (JSON)
• Handling configuration mode via:
  • Serial command (cfg)
  • Long press on reset button
• Saving Wi-Fi + server settings in NVS (Preferences)
• Providing user feedback on OLED + buzzer
• Driving access control output pins

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Backend (Node.js/Express + MongoDB)

Located in:

./Server for RFID/

Backend capabilities:

• Validates RFID card UIDs
• Provides API endpoint (e.g. /api/cards/validate) for device checks
• Stores authorized cards and access logs in MongoDB
• Returns JSON responses with allow flag and optional cardholderName

Running the backend

cd "Server for RFID"
npm install
npm start

Requirements:

• A running MongoDB instance
• A .env file containing something like:

  MONGODB_URI=your_connection_string_here
  SERVER_PORT=3000

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Enclosure (3D Design)

3D files are stored in:

./enclosure/

Includes:

• .stl and/or .step CAD files
• Photos of the printed and assembled enclosure (./docs/images/enclosure-*.jpg)

Example gallery (replace with real paths):

### Enclosure Photos

<p align="center">
  <img src="./docs/images/enclosure-front.jpg" width="320">
  <img src="./docs/images/enclosure-side.jpg" width="320">
</p>

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Usage Instructions

1. Power On

When powered, the ESP32:

1. Loads saved Wi-Fi + server settings from NVS
2. Attempts to connect to the configured Wi-Fi network
3. Enters normal operation once connected

If settings are invalid, the device will still stay in normal loop, but you can always enter configuration mode manually (see below).

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2. Normal Operation

1. Present an RFID card near the MFRC522 reader
2. The device reads the UID and normalizes it
3. Sends an HTTP POST request to SERVER_URL with UID, MAC, IP, RSSI, etc.
4. Backend returns JSON with an allow flag and optional card.cardholderName
5. Device behavior:
   • On ALLOW:
     • Plays “access granted” buzzer pattern
     • Activates grant outputs (SIGNAL_PIN_HIGH_1, SIGNAL_PIN_HIGH_2, SIGNAL_PIN_LOW)
     • Displays Welcome + cardholder name on OLED
   • On DENY:
     • Plays “access denied” buzzer pattern
     • Displays Access Denied

Backend logs all attempts.

You can later attach a relay or lock to the signal pins.

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Configuration Mode

Configuration mode lets you set Wi-Fi SSID, password and backend URL.
There are two ways to enter it: button or serial.

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A) Using the Reset Button (5-second Hold)

Your enclosure has a pinhole aligned with the reset/config button.

1. Insert a SIM-tool-style pin or thin rod

2. Press and hold the button for about 5 seconds

3. The device:

   • Switches to AP mode
   • Starts a config access point:

     SSID: DoorConfig
     Password: 12341234
     

   • Starts the web UI on 192.168.4.1
   • Shows “configuration mode active” on the OLED
   • Plays a triple config tone on the buzzer

4. Connect your phone or laptop to the Wi-Fi network DoorConfig

5. Open a browser and go to:

http://192.168.4.1/

6. Log in with password: 12341234

7. Use the form to set:

   • Wi-Fi SSID
   • Wi-Fi password
   • Server URL (SERVER_URL)

8. Click Save & Reboot

   • Settings are written to NVS
   • Device restarts and attempts to connect with the new settings

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B) Using Serial Command (cfg)

You can also enter configuration mode via USB serial:

1. Connect the ESP32 to your computer
2. Open a serial monitor (115200 baud)
3. Type:

cfg

and press Enter.

4. Device enters “serial configuration mode” and prompts you in the terminal for:
   • New Wi-Fi SSID
   • New Wi-Fi password
   • New server URL

Press Enter on any field to keep the current value.

5. Confirm with y to save changes, or any other key to discard.
6. On save:
   • Settings are written to NVS
   • Device plays a “success” tone
   • Device restarts using the new configuration

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Web Admin UI on LAN

When the device is already connected to your Wi-Fi network, you can also access the configuration UI via its LAN IP:

1. Find the device IP address in your router or via serial logs
2. Open:

http://<device-ip>/

3. Log in with password:

12341234

4. You’ll see the same configuration form as in AP mode (/cfg route).
5. Saving configuration will also reboot the device.

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Notes on Behavior

• Wi-Fi reconnection is handled by ensureWiFi() with retries and error display.
• If Wi-Fi or server are down, the device shows error messages and plays an error tone, but you decide when to enter config mode (via button or cfg).
• Duplicate card reads within a short cooldown (CARD_COOLDOWN_MS) are ignored to avoid spamming the backend.

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What I Learned

• Designing a full end-to-end embedded + backend access control system
• Interfacing ESP32 with MFRC522 and SSD1306 OLED
• Implementing Wi-Fi connectivity, HTTP requests, and JSON handling on microcontrollers
• Building REST APIs with Node.js/Express and integrating them with MongoDB
• Using non-volatile storage (Preferences) for device configuration
• Building a simple but effective web admin panel on an ESP32 using WebServer
• Designing and printing a custom enclosure for an electronic device

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License

Released under the MIT License.
See the LICENSE file for full details.