✅ ESP32 Smart Door Lock (Blynk IOT)

ESP32 + Servo + Solenoid Lock + 1-Channel Relay

✅ ESP32 code (Servo + Relay + Solenoid)
✅ Full code explanation
✅ Blynk Dashboard setup
✅ Virtual Pins (V0, V1 etc.)
✅ Buttons + Status display

✅ 1) What You Will Control in Blynk

We will control:

🔘 Button 1 (V0)

• ON = Unlock

• OFF = Lock

📌 Status (V1)

• Shows “LOCKED / UNLOCKED”

✅ 2) Blynk Setup (Step-by-Step)

🔹 Step 1: Create New Template

1. Open Blynk IoT App

2. Go to Developer Zone

3. Click New Template

4. Template Name: Smart Door Lock

5. Hardware: ESP32

6. Connection Type: WiFi

7. Create

🔹 Step 2: Create Datastreams (Virtual Pins)

Go to your template → Datastreams → Add New:

✅ Datastream 1 (Button)

• Name: Door Lock

• Type: Virtual Pin

• Pin: V0

• Data Type: Integer

• Min: 0

• Max: 1

• Default: 0

✅ Datastream 2 (Status)

• Name: Lock Status

• Type: Virtual Pin

• Pin: V1

• Data Type: String

🔹 Step 3: Create Web Dashboard / Mobile Dashboard

Go to template → Web Dashboard (or Mobile Dashboard):

Add Widget 1: Button

• Type: Button

• Datastream: Door Lock (V0)

• Mode: Switch

• ON = 1

• OFF = 0

Add Widget 2: Label / Value Display

• Type: Label

• Datastream: Lock Status (V1)

🔹 Step 4: Create Device

1. Go to Devices

2. Add New Device

3. Choose your Template

4. Create

5. Copy:
   ✅ Auth Token

✅ 3) ESP32 Blynk Code 

#define BLYNK_PRINT Serial

// ------------ Blynk Credentials ------------
#define BLYNK_TEMPLATE_ID "PASTE_TEMPLATE_ID"
#define BLYNK_TEMPLATE_NAME "Smart Door Lock"
#define BLYNK_AUTH_TOKEN "PASTE_AUTH_TOKEN"

// ------------ Libraries ------------
#include <WiFi.h>
#include <BlynkSimpleEsp32.h>
#include <Servo.h>

// ------------ WiFi Credentials ------------
char ssid[] = "YOUR_WIFI_NAME";
char pass[] = "YOUR_WIFI_PASSWORD";

// ------------ Pins ------------
#define SERVO_PIN 13
#define RELAY_PIN 26

// ------------ Servo ------------
Servo lockServo;

// Servo angles (change for your door)
int LOCK_ANGLE = 0;
int UNLOCK_ANGLE = 90;

// Door status
bool isUnlocked = false;

// ------------ Function Prototypes ------------
void lockDoor();
void unlockDoor();
void sendStatusToBlynk();

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

// Relay
pinMode(RELAY_PIN, OUTPUT);
digitalWrite(RELAY_PIN, LOW); // solenoid OFF

// Servo
lockServo.attach(SERVO_PIN);
lockServo.write(LOCK_ANGLE);

// Start Blynk
Blynk.begin(BLYNK_AUTH_TOKEN, ssid, pass);

Serial.println("✅ ESP32 Door Lock with Blynk Started!");

sendStatusToBlynk();
}

void loop() {
Blynk.run();
}

// ---------------- BLYNK BUTTON CONTROL ----------------
// V0 = Door Lock Button
BLYNK_WRITE(V0) {
int value = param.asInt();

if (value == 1) {
unlockDoor();
} else {
lockDoor();
}
}

// ---------------- FUNCTIONS ----------------

void unlockDoor() {
Serial.println("🔓 Unlocking...");

// Servo unlock
lockServo.write(UNLOCK_ANGLE);
delay(700);

// Relay ON (Solenoid ON)
digitalWrite(RELAY_PIN, HIGH);
delay(200);

isUnlocked = true;

sendStatusToBlynk();
}

void lockDoor() {
Serial.println("🔒 Locking...");

// Relay OFF (Solenoid OFF)
digitalWrite(RELAY_PIN, LOW);
delay(200);

// Servo lock
lockServo.write(LOCK_ANGLE);
delay(700);

isUnlocked = false;

sendStatusToBlynk();
}

void sendStatusToBlynk() {
if (isUnlocked) {
Blynk.virtualWrite(V1, "UNLOCKED 🔓");
} else {
Blynk.virtualWrite(V1, "LOCKED 🔒");
}
}

✅ 4) Code Explanation (Very Clear)

🔹 1) Blynk Credentials

These connect your ESP32 to your Blynk project.

🔹 2) WiFi Connection

This automatically:
✅ connects WiFi
✅ connects Blynk cloud

🔹 3) Blynk Virtual Pin Control (V0)

Whenever you press the Blynk button, ESP32 receives:

• 1 → unlock

• 0 → lock

🔹 4) Sending Status to Blynk (V1)

This sends door status text to your Blynk dashboard label widget.

🔹 5) Unlock Process

Inside unlockDoor():

1. Servo rotates to unlock angle

2. Relay ON → solenoid activates

3. Status updated in app

🔹 6) Lock Process

Inside lockDoor():

1. Relay OFF

2. Servo back to lock angle

3. Status updated in app

⚠️ IMPORTANT NOTE (Relay Logic)

Some relay modules work reverse.

If your solenoid activates when it should be OFF:

Swap these in code:

Relay ON:

Relay OFF: