PC Controlled Home Automation using Arduino

PC Controlled Home Automation using Arduino

This project explains designing a home automation system which is controlled by a computer to switch On and switch Off various electrical and electronics devices. For demonstration we have used 3 zero watt bulbs which indicates LIGHT, FAN and TV. It uses Arduino Uno board as a controller and a 5V relay to connect light bulbs with the circuit.

There could be various types of communications to control devices like home appliances, industrial appliances, etc. Broadly we can categorize them as wired and wireless. For example in wireless communication we transmit signal using radio frequency (RF) and in wired communication we use wires. Wired communication can further be categorized as:

1.  Parallel communication

2.  Serial Communication

In parallel communication we use many wires depending on the data size in bits, i.e. if we need to transmit 8 bit then we would need a 8-bit wire. But in serial communication we only used two wires for transmitting data and receiving data as in serial communication data are transmitted serially i.e. bit by bit. 

Components Required

1.  Arduino UNO

2.  Serial Cable

3.  ULN2003

4.  Relay 5 volt

5.  Bulb with holder

6.  Connecting wires

7.  Bread board

8.  16x2 LCD

9.  Laptop

10. Power supply

11. PVT

Relay

We need a relay to connect the circuits with higher voltage AC appliances like bulb, TV, fan, etc. Relay is a kind of switch which is used for electronic to electrical interfacing. Relays contain a coil and some switching contact cores. There are different types of relays, like:

1.  Single Pole Single Through (SPST).

2.  Single Pole Double Through (SPDT).

3.  Double Pole single Through (DPST).

4.  Double Pole Double Through (DPDT).

Here we have used single pole double through (SPDT) relay. SPDT relays contain five pins, in which 2 pin for coil and one is for pole and other two are namely "Normally Connected" (NC) and "Normally Open" (NO).

Circuit Diagram and Explanation

As shown in the above schematic diagram above, a 16x2 LCD module is used for displaying status of home appliances which is directly connected to arduino in 4-bit mode. Data pins of LCD namely RS, EN, D4, D5, D6, D7 are connected to arduino digital pin number 7, 6, 5, 4, 3, 2. For sending commands to arduino from laptop or PC we uses USB cable that we used for uploading program into arduino. And a relay driver IC ULN2003 is also used for driving relays. 5 volt SPDT 3 relays are used for controlling LIGHT, FAN and TV. And relays are connected to arduino pin number 3, 4 and 5 through relay driver IC ULN2003 for controlling LIGHT, FAN and TV respectively.

Here serial communication is used to control the home appliances. We send commands like LIGHT ON, LIGHT OFF, FAN ON, FAN OFF, TV ON AND TV OFF to control AC home appliances. After receiving the given commands, arduino send signal to relays which are responsible for switching on or off of the appliances.

When we press ENTER after typing one of any given command on hyper terminal or serial terminal, arduino performs relative task like turning on the “fan” and likewise other tasks. And a relevant message is also displayed on 16x2 LCD which is programmed in the code. (See the code section in bottom)

Code Explanation

First of all we include library for liquid crystal display and then we defines data and control pins for LCD and home appliances.

After it serial communication is initialized at 9600 bps and gives direction to use pin.

For receiving data serially we use two functions - one is Serial.available which checks any serial data is coming or not and other one is Serial,read which reads data that comes serially.

After receiving data serially we store it in a string and then wait for Enter.

When enter is pressed program start to compare received string with already defined string and if string matched then a relative operation is performed by using appropriate command that are given in code.

For using compare string we have used a library that is string.h which has some keywords like strcmp, strncmp, strcpy etc.

       Demo & Code

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