In this technological advance era, automation is a necessity. Automation is the use of technological appliances to perform a task with minimum human input. The automation of the home is called as smart home. Smart home Automation makes the lives easy of humans by monitoring the data, providing safety, and maximizing the efficiency of the resources used in our homes and increasing the convenience to manage our homes. The devices used in the smart homes are mostly Radio Frequency (RF) based communications methods between devices.

Arduino Uno:

The 8 – bit ATmega 328P microcontroller-based Arduino UNO is used in this system to control different components like HC – 05 Bluetooth module and relay network.

HC – 05 Bluetooth Module:

The Bluetooth Module used in this smart home automation system is HC-05 as the image below. It has 4 – pins for VCC (5V), ground, TX and RX. This Bluetooth Module can be used with Bluetooth enabled phone, tablet or laptop, and the range of this module is around 10 meters.

4 – Channel Relay Board:

A 4 – channel relay board is used in this smart home automation system to control four different loads. It has components and connections such as the base current limiting resistor, flyback diode, LED indicators and header for connecting it to other devices.

Circuit Design:

The circuit design of the Smart Home Automation is based on Arduino Uno and HC-05 Bluetooth Module. The Bluetooth module has 4 – pins: VCC, Transmitter, Receiver and Ground. VCC and Ground are connected to 5V and ground from Arduino. The HC – 05 Bluetooth module works on 3.3V and it has an on board 5V to 3.3V regulator. The Transmitter and Receiver pins of the Bluetooth module must be connected to RX and TX pins of the Arduino. In Arduino Uno, we are defining pins 2 and 4 as Receiving and Transmitting using the software. Therefore, the TX of Bluetooth is connected to the pin 4 of Arduino Uno. But when connecting RX of Bluetooth to TX of Arduino, we need to be very careful as the pin can only tolerate only 3.3V. But the voltage from TX or Arduino Uno will be only 5V. So, a voltage divider network having 10K and 20K resistors are used to reduce the voltage to 3.3V approximately. Any combination of resistors can be used to bring down the voltage to around 3.3V. The next step is to connect the digital I/O pins of the Arduino Uno to input of the relay board.

Working Process:

A smart home automation system using Arduino UNO, Bluetooth module, 4 – Channel Relay and a smartphone. The aim of this smart home automation system is to control different types of home appliances using a smartphone, Tablet, Laptop and other devices. The working of the smart home automation system is explained here in detail. When the power is turned On, the connection LED on the HC – 05 Bluetooth module starts blinking. We need to start the “Bluetooth Controller” application in our smartphone and get connected to the HC – 05 Bluetooth module. When the Bluetooth paired, the LED becomes stable. Now, in the application, we need to set different keys for different loads and their corresponding values, that must be transmitted when that key is pressed. When a key is tapped in the smartphone, table, laptop or other devices, the HC – 05 Bluetooth module receives the data and intern transmits that data to Arduino Uno.


  • By Using this smart home automation system, we can turn on or off appliances remotely i.e., using a phone, tablet or Laptop.
  • The RF Communication method can be further expanded by including some sensors like light sensors, temperature sensors, safety sensors etc. and automatically adjust different parameters like room lighting, air conditioning (room temperature), door locks etc. and transmit the information to our phone.
  • We can also connect to internet and control the home from remote location over internet and monitor the safety.
  • With the help of this RF Communication method, a mic and speaker can be connected to the system and voice command can be given to control the appliances.


            RF Communications has introduced the implementation a low cost, flexible and wireless, power efficient solution to home automation. The Radio frequency has adequate transmission and reception for fast communication between devices. The use of RF signals is a safe mode of communication. The RF Communication method is a reliable mode of communication.