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Homote — Your Home Automation Remote

Create your own Cost-efficient Home Automation System with a NodeMCU, Relay Module and Battery

Photo by Ihor Saveliev on Unsplash

So, this article expects to provide the technology-ready class with an affordable solution for the obstacle that is home automation and it’s sky high prices.

What is Home Automation?

What is the purpose of the article?

Photo by Sebastian Scholz (Nuki) on Unsplash

The Home-Automation systems in today’s world are either too difficult to use for a user who is not familiar to the technology or too expensive to be used by the average citizens. Hence, with this home-automation system, I hope to provide a cost-effective solution to this conundrum.

Components Required


  • Low-power, highly-integrated Wi-Fi solution
  • A minimum of 7 external components
  • Wide temperature range: -40°C to +125°C
  • ESP8285–8 Mbit flash embedded
ESP8266 — Block Diagram | Image by Ligo George on his article on electrosome

Relay Module

  • One is the Trigger Voltage — this is the voltage required to turn on the relay, i.e., to change the contact from Common -> NC to Common -> NO. Our relay here has 5V trigger voltage.
  • The other parameter is your Load Voltage & Current, this is the amount of voltage or current that the NC, NO or Common terminal of the relay could withstand, in our case for DC it is maximum of 30V and 10A.
5V Relay Switch — Block Diagram | Image from Components101 Article
  • It is commonly used in switching circuits.
  • Also used for Home Automation projects to switch AC loads
  • Used to Control (On/Off) Heavy loads at a pre-determined time/condition
  • Used in safety circuits to disconnect the load from supply in event of failure
  • Used in Automobiles electronics for controlling indicators glass motors etc.

Product Specifications & Features

  • With the help of this mobile application for the home remote, and a very cost efficient solution to the problem of home automation, users will have the option of performing simple yet important activities with just a tap on their mobile phone rather than actually having to do the work by themselves.
  • The system will be able to provide the user with the option to perform certain actions one after another without any exaggerated delays.
  • In the Arduino IDE application, we upload the code to the NodeMCU which gets the wifi SSID and password which already makes way for only the users with access to the wifi router in their home to be authorised.
  • As such, there is no authorisation page in the android application but it provides with a section to fill with IP address which can only be known to the user and hence only the authorised user is able to use it.
  • A constantly strong internet connection is a must for the system to perform its functions in a normal way.
  • Another constraint for the system is that the actions can be only performed after the completion of another action,i.e. User can’t perform two actions simultaneously as a certain pin number and other information is sent to the NodeMCU from the application and hence they have to perform one after another.
  • Electricity is required constantly for all the devices to be controlled via Arduino.
Use Case of Homote | Image by Author


Sequence Diagram

Sequence Diagram | Image by Author

State-Transition Diagram

State-Transition Diagram | Image by Author

Data Flow Diagram

Data Flow Diagram | Image by Author

Circuit Diagram

Circuit Diagram | Image by Author
  • The NodeMCU is connected to the relay via its digital pins (say, D1,D2,D3,D4) and to the power supply through the micro USB to a computer (this can be changed as per your needs later on).
  • The relay has its input pins connected to NodeMCU, GND pin & VCC to GND and 3.3V of NodeMCU respectively, the battery’s positive terminal to the common terminal, negative terminal to LED(s)’ negative terminal(s) and the LED(s)’ positive terminal to the normally open terminal.

User Interface

NodeMCU Code
Blynk Application Interface | Image by Author



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