IOT Home Automation using Blynk and NodeMCU

NodeMCU is very popular in Home Automation. It’s WiFi capabilities and Arduino IDE support making it easier for IoT Applications. It is very tiny and has many Digital I/O pins, Serial Communication and I2C Communication. NodeMCU has a micro USB port to program it using your existing mobile cable (no additional programmer needed). There is a successor called ESP32 Development board which has more Analog pins and Digital pins. You can use any one of them for this project according to your requirements. Here we will be using NodeMCU.

Blynk is a mobile application which has its own server to process user requests. It is an open source application and anybody can use it in their Home Automation to control devices, monitor sensor data and get a notification by some trigger actions. It has a nice GUI with Graphs, Timers, Slider, Joystick and even Video Streaming. You can also make your own app and publish it in Google play store.

Components required:

Hardware:

• NodeMCU Development board – Buy Now
• 4 Channel Relay – Buy Now
• USB cable

Software required:

• Blynk App
• Arduino IDE

Circuit Diagram:

Example Relay connection with AC Devices. Consider the relay as a switch:

Note: For example purpose, we have connected Relay at D0, D1, D2 and D3. You need to make sure there should not be alternate functions to that pins. Because the D0 pin has connected with Onboard LED (D4 has TXD1 function), whenever you Power ON the NodeMCU it blinks for a second. In case you have connected a Tube Light, it will flash during startup. So please refer the NodeMCU pinout and assign the proper pins without any conflictions.

P.S – I found that the D1, D2, D5, D6 are good to use for without any flickering of Relays.

Caution: If you are using AC Power supply, please connect it carefully as it is High Voltage and have Risk of electric shock or short circuit.

Check this tutorial for Voice Controlled Home Automation using Google Assistant – an upgraded version of this tutorial.

Check this tutorial for implementing this Relay with Two-Way Switches to control from both of them.

NodeMCU Pinout:

Download Blynk Application from Google Play store:

Download and install the Blynk App Here:

Android

Apple

Create a Blynk App:

Step1: For new users Sign Up and old users just Log in.

Step2: Create a New Project and Choose NodeMCU board in the Choose device drop-down and then click create.

Step 3: Now you will receive an email with the Authentication Token. You need to place it in the Arduino Code. Before that, we will finish the App Creation.

Step 4: Click on the ‘+’ Icon on the top right corner. Now Widget box will open, We need 4 buttons to control the relay. So add 4 buttons by choosing it here.

Step 5: Now tap on the button from the Homepage to configure it. Choose the Output Pin D0 and Select the Mode as Switch. Then go back. Configure the remaining buttons in the same way.

Step 6: Now we have the App ready.

Step 7: Now connect the NodeMCU to the PC and open Arduino IDE.

Install the Blynk library from Sketch>Include Library> Manage Library and search for blynk and install it. Or you can install using Git Method from here.

In case, you are using ESP8266 or NodeMCU for the first time you need to add NodeMCU on boards manager and the ESP8266Wifi.h library to be installed. Otherwise, skip to step 8.

Installing ESP8266 Boards:

Navigate to Tools>Board>Boards Manager. Search for esp8266 and install esp8266 boards.

Installing Arduino Master (or Arduino Core) library:

The ESP8266Wifi.h library is included in Arduino Master(Core Library). You need to download and extract the file. Then navigate to libraries in the extracted file (Example: C:\Users\YourPCName\Downloads\Arduino-master\Arduino-master\libraries). Then copy all ESP Related folders or all the folders (depending upon your choice) and paste in inside C:\Program Files (x86)\Arduino\libraries.

Source Path (Extracted File location of Arduino Core library)

Destination Path (Arduino Libraries location)

Now we have set up everything.

Step 8: Copy the following code or Open File->Examples and navigate to Blynk->WiFi->NodeMCU.

You need to modify only three things in this code.

Paste the Authentication Token that you received in your email at ‘YourAuthToken’. Then add your SSID and Password in the code as ‘YourNetworkName’ and ‘YourPassword’.

Note: In some cases, it might show you warnings for ‘Multiple Libraries found’. It is just a warning to acknowledge which library it is using. Because the Arduino and esp8266 core library have the same libraries. Example Servo.h library. Simply ignore it and upload the program.

/*************************************************************

Download latest Blynk library here:

https://github.com/blynkkk/blynk-library/releases/latest

Downloads, docs, tutorials: http://www.blynk.cc

Sketch generator:           http://examples.blynk.cc

Blynk community:            http://community.blynk.cc

*************************************************************

This example runs directly on NodeMCU.

Note: This requires ESP8266 support package:

https://github.com/esp8266/Arduino

Change WiFi ssid, pass, and Blynk auth token to run :)

*************************************************************/

#define BLYNK_PRINT Serial

#include <ESP8266WiFi.h>

#include <BlynkSimpleEsp8266.h>


// You should get Auth Token in the Blynk App.

// Go to the Project Settings (nut icon).

char auth[] = "YourAuthToken";


// Your WiFi credentials.

// Set password to "" for open networks.

char ssid[] = "YourNetworkName";

char pass[] = "YourPassword";


void setup()

{
/*To avoid relays chatters when connected to blynk, set the pin to HIGH (for Relays that turns OFF at HIGH) 
before blynk.begin function. Eg. for D3 Given Below */

//pinMode(D3, OUTPUT);
//digitalWrite(D3, HIGH);

Serial.begin(9600);

Blynk.begin(auth, ssid, pass);

Blynk.syncAll(); //This will sync the last state of your device

}

void loop()

{

Blynk.run();

}

Once it completes, Choose the right port and Board then upload the code. That’s it! Your Home Automation Project is ready. You can test it in your Blynk app by turning ON and OFF. It can work from anywhere in the world with an internet connection.

The advanced version of the app is continued in the next tutorial. It can control the devices using your Voice Commands using Google Assistant on your Phone or Google Home. Check out the tutorial, if you want to upgrade your project with Voice Control – Voice Controlled Home Automation | Google Assistant | NodeMCU