Smart door access control using ESP32 and RFID card

Tutorial plan

1- Introduction

2- Description of ESP32 Smart Door Access

3- Required Components

4- Circuit Connections of system

5- Micropython program of system

Introduction

A Smart Door Access Control System using a reader card is an electronic security system that restricts or grants access to a building or room based on the authentication of a card. It is widely used in homes, offices, schools, hospitals, and industrial facilities to enhance physical security.

Key Components (General)

1. Reader Card System (RFID/NFC/Magnetic Stripe Reader):

Scans or reads a card that contains user identification data.

Most commonly uses RFID (Radio Frequency Identification) or NFC (Near Field Communication).

Can be contactless or swipe-based.

2. Identification Card/Tag:

A card (e.g., RFID card, NFC tag, smart ID) containing a unique ID number.

Acts as the user's key.

3. Access Control Unit (Controller):

The central processor (microcontroller, computer, or cloud-based system).

Compares the card’s ID with a list of authorized users stored in memory or database.

Makes decisions (grant or deny access).

4. Door Lock Mechanism:

Typically an electromagnetic lock, electric strike lock, or servo/solenoid-based system.

Unlocks automatically when access is granted.

5. Power Supply:

Provides necessary voltage and current to all components.

Usually includes backup battery support for power failures.

6. Feedback Mechanisms (Optional):

Display (LCD/OLED): To show messages (e.g., Access Granted/Denied).

Buzzer: For audible feedback.

LEDs: For visual status indication.

How It Works – Step-by-Step

1- User presents their card near the reader or swipes it.

2- Card reader reads the unique ID from the card.

3- Controller receives and verifies the ID against a list of authorized users:

4- Stored locally in memory (microcontroller systems) or remotely in a cloud-based or database system.

5- Based on the result:

a) If Authorized:

- Controller activates the lock to open the door.

- Feedback is provided (e.g., green LED, beep, “Access Granted” on screen).

b) If Not Authorized:

- Access is denied.

- Red LED or buzzer alerts user.

- The door is automatically relocked after a certain time (usually 3–10 seconds).

Features and Benefits

Security

- Prevents unauthorized access.

- Tracks entries with time logs (optional).

Convenience

- Fast and contactless access with just a card swipe or tap.

Automation

- Reduces human involvement in access management.

Scalability

- Supports addition/removal of users easily.

- Can be extended to multiple doors or zones.

Description of ESP32 Smart Door Access

This system allows or restricts access to a door using an RFID card. The ESP32 microcontroller reads the card's unique ID via the RC522 RFID reader, compares it with stored authorized IDs, and opens the door (via a servo motor) if access is granted. A message is displayed on an LCD I2C display to inform the user of the result.

How It Works

1- Initialization

On startup, the ESP32 initializes all components: RFID reader, LCD, and servo.

The LCD displays a message like “Scan your card”.

2- Card Scanning

When a card is brought near the RC522 reader, it captures the card’s UID (Unique Identifier).

3- UID Comparison

The UID is compared with a list of authorized UIDs stored in the ESP32’s memory (e.g., in code or EEPROM).

4- Access Decision

a) If UID matches an authorized user:

LCD displays “Access Granted”.

Servo rotates to unlock the door (e.g., 20°).

The user approaches the RFID card to the RC522 reader again, the servomotor close the door (e.g., 90°).

b) If UID is unauthorized:

LCD displays “Access Denied”.

Servo remains in the locked position.

5- Repeat

The system loops, waiting for the next card scan.

Required Components

ESP32 Microcontroller

Role: Acts as the central control unit for the entire smart door system

RFID-RC522 Reader Module

Role: Reads the UID (Unique Identifier) from an RFID card or tag.

RFID Card / Tag

Role: Provides a unique digital key that identifies a user.

Servo Motor (e.g., SG90 or MG90S)

Role: Physically acts as the door lock actuator by rotating between locked and unlocked positions.

LCD I2C Display

Role: Displays system status and user prompts (e.g., “Scan Card”, “Access Granted”).

Breadboard

Role : is used for prototyping and connecting components without soldering.

Jumper Wires

Role: are used to make connections between components on the breadboard, Micro:bit, and GPIO extension card.

Wooden house prototype

A miniature wooden house represents a real-world structure.

The door mechanism is attached to a servo motor, which rotates to open or close it.

The wooden prototype provides a stable frame for installing components like the IR sensor and LCD screen.

Circuit Connections of system

Connection of I2C LCD display

Connection of servo motor

Connection of RFID-RC522 module

Micropython program of system

Before running the code, install the necessary libraries:

- MFRC522 (for RFID module)

- i2c_lcd and lcd_api for I2C LCD screen

- Servo (for servo motor)