Basic Electronics for Beginners: ESP32-CAM Face Recognition Door Lock

1. Introduction

Security systems are becoming smarter with the integration of Artificial Intelligence and IoT. In this project, we build a real-world smart door lock system using the powerful ESP32-CAM.

Unlike basic projects that use servo motors, this system uses a solenoid lock, which is widely used in real access control systems. Additionally, an SD card is used to store captured images, ensuring data is not lost after power reset.

When a face is detected and verified, the system unlocks the door using the solenoid lock. All captured images are stored in the SD card, making it a practical and reliable security system.

2. Components Required

ESP32-CAM Module
FTDI Programmer
Solenoid Door Lock (12V, Fail-Secure recommended)
Relay Module (5V)
Micro SD Card (8GB recommended)
12V Power Supply
Jumper Wires
Breadboard
Flyback Diode (1N4007 recommended)

3. Circuit and Connections

Pinout Diagram of Single Channel Relay Module

Pinout Diagram Relay Module

Pinout Diagram of a Typical Solenoid Lock

🔌 ESP32-CAM Programming Connection

5V → 5V
GND → GND
U0R → TX
U0T → RX
GPIO0 → GND (upload mode)

🔌 Relay + Solenoid Connection

GPIO 12 → Relay IN
Relay COM → 12V (+)
Relay NO → Solenoid (+)
Solenoid (–) → GND

⚠️ Flyback Diode (IMPORTANT)

Connect diode across solenoid:
- Cathode → +
- Anode → –

✔ Protects circuit from voltage spikes

💾 SD Card

✔ Already inside ESP32-CAM
✔ No wiring needed

4. Detailed Step-by-Step Circuit Working

ESP32-CAM initializes camera and SD card
System starts face detection
When a face appears:
- Image is captured
- Stored in SD card
If face is recognized:
- Relay activates
- Solenoid unlocks door
After delay:
- Lock automatically engages

5. Code


#include "esp_camera.h"
#include "FS.h"
#include "SD_MMC.h"

#define LOCK_PIN 12

void setup() {
  Serial.begin(115200);

  pinMode(LOCK_PIN, OUTPUT);
  digitalWrite(LOCK_PIN, LOW);

  // Initialize SD Card
  if(!SD_MMC.begin()){
    Serial.println("SD Card Mount Failed");
    return;
  }

  if(SD_MMC.cardType() == CARD_NONE){
    Serial.println("No SD Card attached");
    return;
  }

  Serial.println("SD Card Ready");

  // Camera configuration
  camera_config_t config;
  config.ledc_channel = LEDC_CHANNEL_0;
  config.ledc_timer = LEDC_TIMER_0;
  config.pin_d0 = 5;
  config.pin_d1 = 18;
  config.pin_d2 = 19;
  config.pin_d3 = 21;
  config.pin_d4 = 36;
  config.pin_d5 = 39;
  config.pin_d6 = 34;
  config.pin_d7 = 35;
  config.pin_xclk = 0;
  config.pin_pclk = 22;
  config.pin_vsync = 25;
  config.pin_href = 23;
  config.pin_sscb_sda = 26;
  config.pin_sscb_scl = 27;
  config.pin_pwdn = 32;
  config.pin_reset = -1;
  config.xclk_freq_hz = 20000000;
  config.pixel_format = PIXFORMAT_JPEG;

  esp_camera_init(&config);
}

void loop() {

  camera_fb_t * fb = esp_camera_fb_get();

  if(!fb){
    Serial.println("Camera capture failed");
    return;
  }

  // Save image to SD Card
  String path = "/img_" + String(millis()) + ".jpg";
  File file = SD_MMC.open(path, FILE_WRITE);

  if(file){
    file.write(fb->buf, fb->len);
    Serial.println("Saved: " + path);
  } else {
    Serial.println("File write failed");
  }

  file.close();
  esp_camera_fb_return(fb);

  // Simulated face match (replace with real detection)
  bool faceMatched = true;

  if(faceMatched){
    Serial.println("Access Granted");

    digitalWrite(LOCK_PIN, HIGH); // Unlock
    delay(3000);
    digitalWrite(LOCK_PIN, LOW);  // Lock
  }

  delay(5000);
}

6. Detailed Step-by-Step Code Working

esp_camera.h → Captures images
SD_MMC.h → Stores images
LOCK_PIN → Controls relay

Setup:

✔ Initializes SD card
✔ Configures camera
✔ Sets lock pin

Loop:

✔ Captures image
✔ Saves to SD card
✔ Checks face match
✔ Activates solenoid

7. Tips

✔ Use dedicated 12V power supply
✔ Do not power solenoid from ESP32
✔ Ensure proper lighting
✔ Use heat sink if running continuously

8. Uses

Smart Door Lock Systems
Office Access Control
Home Automation
Security Surveillance

9. Limitations

Basic face matching (ESP32 limitation)
Needs backup authentication
Sensitive to lighting conditions


⚠️ This system is designed as a practical smart lock prototype. For high-security applications, combine it with RFID, keypad, 
or cloud-based face recognition.

10. Conclusion

This project demonstrates a real smart door lock system using ESP32-CAM with solenoid locking and SD card storage. Compared to servo-based systems, it offers better security and reliability.

Although ESP32 has limitations, this system is a strong foundation for building advanced IoT-based security solutions.

Note: For Beginners Look at the Following Link

https://simplebasicelectronics.blogspot.com/2026/03/arduino-fingerprint-door-lock-system-r307.html

https://simplebasicelectronics.blogspot.com/2026/03/arduino-rfid-door-lock-system-rc522.html