Smart Door Lock RFID with Mobile Logging System

A complete offline IoT project using ESP32 + RFID RC522 + Flutter.

---

📦 Project Structure

smart_door_lock/
├── esp32/
│   └── smart_door_lock.ino       ← Upload this to ESP32
│
└── flutter_app/
    ├── pubspec.yaml
    ├── android/
    │   └── app/src/main/
    │       ├── AndroidManifest.xml
    │       └── res/xml/network_security_config.xml
    └── lib/
        ├── main.dart
        ├── models/
        │   ├── log_entry.dart
        │   └── rfid_card.dart
        ├── screens/
        │   ├── home_screen.dart
        │   ├── logs_screen.dart
        │   ├── manage_cards_screen.dart
        │   └── settings_screen.dart
        └── services/
            ├── api_service.dart
            └── preferences_service.dart

---

🔌 Wiring Diagram

RFID RC522 → ESP32

RC522 Pin    →   ESP32 Pin
─────────────────────────
VCC (3.3V)   →   3.3V
GND          →   GND
SDA (SS)     →   GPIO 5
SCK          →   GPIO 18
MOSI         →   GPIO 23
MISO         →   GPIO 19
RST          →   GPIO 4
IRQ          →   (not connected)

Servo Motor (SG90) → ESP32

Servo Wire   →   ESP32 Pin
───────────────────────────
Signal (orange) →  GPIO 13
VCC (red)       →  5V (VUSB or external)
GND (brown)     →  GND

⚠️ Important: Do NOT power the servo from ESP32's 3.3V. Use the 5V (VUSB) pin or an external 5V supply. High servo current can reset the ESP32 if underpowered.

LCD 16x2 I2C → ESP32

LCD I2C Pin  →   ESP32 Pin
──────────────────────────
VCC          →   5V
GND          →   GND
SDA          →   GPIO 21
SCL          →   GPIO 22

The I2C address is typically 0x27. If LCD doesn't work, try 0x3F. Edit LCD_ADDR in the .ino file.

LEDs → ESP32

LED Color    →   ESP32 Pin   (with 220Ω resistor in series)
────────────────────────────────────────────────────────────
Green LED    →   GPIO 25     → 220Ω → GND
Red LED      →   GPIO 26     → 220Ω → GND

Full Pinout Summary

                    ┌──────────────┐
                    │              │
       RC522 SDA ───┤ GPIO 5       │
       RC522 SCK ───┤ GPIO 18      │
      RC522 MOSI ───┤ GPIO 23      │
      RC522 MISO ───┤ GPIO 19      │
       RC522 RST ───┤ GPIO 4       │
                    │              │
     Servo Signal ──┤ GPIO 13      │
                    │              │
       LCD SDA   ───┤ GPIO 21      │
       LCD SCL   ───┤ GPIO 22      │
                    │              │
       Green LED ───┤ GPIO 25      │
         Red LED ───┤ GPIO 26      │
                    │              │
             GND ───┤ GND          │
             5V  ───┤ 5V / VUSB   │
            3.3V ───┤ 3V3          │
                    └──────────────┘
                         ESP32

---

📚 Arduino Libraries Required

Install these in Arduino IDE (Sketch → Include Library → Manage Libraries):

Library	Install Name	Notes
MFRC522	MFRC522	by GithubCommunity
ESP32Servo	ESP32Servo	NOT the regular Servo lib
LiquidCrystal I2C	LiquidCrystal I2C	by Frank de Brabander
ArduinoJson	ArduinoJson	v6.x or v7.x
WebServer	Built-in with ESP32 board package

ESP32 Board Setup

1. Open Arduino IDE
2. Go to File → Preferences
3. Add to "Additional boards manager URLs":

   https://raw.githubusercontent.com/espressif/arduino-esp32/gh-pages/package_esp32_index.json
   

4. Go to Tools → Board → Boards Manager
5. Search "esp32" → Install "esp32 by Espressif Systems"
6. Select Tools → Board → ESP32 Arduino → ESP32 Dev Module

---

📱 Flutter Setup

Prerequisites

• Flutter SDK installed (flutter.dev)
• Android Studio or VS Code with Flutter extension
• A physical Android or iOS device (for WiFi connectivity)

Steps

cd flutter_app
flutter pub get
flutter run

Note: Must run on a real device, not emulator. The emulator cannot connect to local WiFi networks where ESP32 lives.

---

🌐 WiFi Connection Guide

Option A: ESP32 Access Point Mode (Default, Recommended)

1. Power on the ESP32
2. On your phone → Settings → WiFi
3. Connect to: SmartLock_AP
4. Password: smartlock123
5. Open the app → Settings → IP: 192.168.4.1
6. Tap "Save & Test"

Option B: Router Mode

1. In smart_door_lock.ino, set:

   #define USE_AP_MODE false
   const char* STA_SSID = "YourRouterName";
   const char* STA_PASSWORD = "YourRouterPassword";

2. Upload to ESP32
3. Check your router's admin panel for the ESP32's assigned IP
4. Enter that IP in the Flutter app Settings

---

🔌 API Reference

Base URL: http://192.168.4.1 (or your custom IP)

GET /

Returns API info page (HTML).

---

POST /scan

Manually check if a UID is authorized.

Request Body:

{
  "uid": "AABBCCDD"
}

Response (Granted):

{
  "status": "granted",
  "uid": "AABBCCDD",
  "timestamp": "T+00:05:23"
}

Response (Denied):

{
  "status": "denied",
  "uid": "DEADBEEF",
  "timestamp": "T+00:06:01"
}

---

GET /logs

Returns all access logs (newest first, max 100).

Response:

[
  {
    "uid": "AABBCCDD",
    "timestamp": "T+00:05:23",
    "status": "granted"
  },
  {
    "uid": "DEADBEEF",
    "timestamp": "T+00:04:10",
    "status": "denied"
  }
]

---

POST /add-card

Register a new RFID card.

Request Body:

{
  "uid": "11223344",
  "label": "Guest Key"
}

Response (Success):

{
  "success": true,
  "message": "Card added"
}

Response (Already exists — 409):

{
  "success": false,
  "message": "Card already registered"
}

---

GET /cards

Returns all registered RFID cards.

Response:

[
  {
    "uid": "AABBCCDD",
    "label": "Master Key"
  },
  {
    "uid": "11223344",
    "label": "Spare Key"
  }
]

---

DELETE /card?uid=AABBCCDD

Remove a registered card.

Response (Success):

{
  "success": true,
  "message": "Card removed"
}

Response (Not found — 404):

{
  "success": false,
  "message": "Card not found"
}

---

🔑 How to Get Your RFID Card's UID

1. Open the Flutter app → Connect to ESP32
2. Scan the RFID card on the reader
3. The ESP32 will deny it (since it's not registered yet)
4. Go to View Logs in the app
5. You'll see the new UID in the denied entry
6. Copy that UID
7. Go to Manage Cards → Add Card
8. Paste the UID and give it a label

---

🛠️ Troubleshooting

Problem	Solution
LCD shows nothing	Check I2C address — try 0x3F instead of 0x27
RFID not detecting	Verify SPI wiring; use 3.3V not 5V for RC522
Servo not moving	Power servo from 5V, not 3.3V
App can't connect	Ensure phone is on SmartLock_AP WiFi, not mobile data
HTTP blocked on Android	Verify network_security_config.xml is in place
Serial shows garbage	Set baud rate to 115200 in Serial Monitor
Cards lost on reboot	Normal — cards are in memory. Add persistence with EEPROM/Preferences if needed

---

⚡ Quick Start Checklist

• Wire all components per diagram above
• Install Arduino libraries
• Set WiFi mode in .ino (AP mode is default — no changes needed)
• Upload .ino to ESP32
• Open Serial Monitor (115200 baud) — verify "System Ready"
• Run flutter pub get in flutter_app/
• Run app on real device (not emulator)
• Connect phone to "SmartLock_AP" WiFi
• Open app → Settings → Verify IP is 192.168.4.1 → Save & Test
• Scan a card → Check logs → Add it via Manage Cards
• Scan registered card → Servo unlocks ✓

---

📝 Notes

• Data persistence: Card list and logs are stored in RAM only. They will be lost on ESP32 reboot. For permanent storage, use Preferences.h (ESP32 NVS) or an SD card module.

• Multiple cards: Up to 50 cards supported (MAX_CARDS constant).

• Auto-lock: Door locks automatically after 3 seconds (LOCK_DELAY_MS).

• Timestamps: Format is T+HH:MM:SS (time since boot). To use real clock time, add an RTC module (DS3231) or use NTP if connected to internet. "# smart_door_lock"