Let us build a home automation system that can control electrical appliances such as lights, fans, gates etc suing our mobile phone from anywhere around the world. All you need is a Raspberry Pi
, some relays and an android phone. Lets get started.
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Step 1 – The Relay
Relays are switching circuits that can close and break circuits mechanically. That means it can control an electrical circuit by closing and breaking connections in that circuit.
As you can see, there are mainly 5 terminals in a relay. Two for energizing the coil, one Common
terminal, a Normally Closed
terminal which will be connected to the Common
terminal when the coil is not energized and a Normally Open
terminal which will be in contact with the Common
terminal when the coil is energized.
This is how the relay works. In our case, we will be connecting
- GPIO pins to One End of Coil
- Ground to other End of Coil
- Phase of Main Power Supply to The Common terminal or Pole
- One Terminal of bulb (Or other electrical Appliance) to Normally Open Terminal
- And the Other Terminal of Bulb to Neutral Point of Main Power Supply
Since the Output of Raspberry Pi
GPIO pins are 3.3V, you will have to buy
a 3.3V Relay. You can purchase the relay board of 4 relays that is compatible with Raspberry Pi from here
or click on the image.
Step 2 – The Raspberry Pi
Raspberry Pi is a low cost single board computer which can be used for robotics, home automation etc.
Get your Raspberry Pi from Here
Download and burn an OS to a micro SD card and insert it into the raspberry Pi. In this project, I used Raspbian OS. You can download the OS by clicking the below link Download
Now power it up. Now fire up your terminal and create a password for the user ‘pi’ by executing the command
sudo passwd pi
Now perform and update and upgrade by running
sudo apt update -ysudo apt upgrade -y
Now you can connect GPIO pins to Relay board
- GPIO 11 to Relay 1 Controlling Device 1
- GPIO 13 to Relay 2 Controlling Device 2
- GPIO 15 to Relay 3 Controlling Device 3
- GPIO 29 to Relay 4 Controlling Device 4
Step 3 – The Network
Connect your Raspberry Pi to a WiFi router
or Wired network and make sure it is connected by checking whether it is getting an IP address from the switch. Connect your mobile phone to the same network and make sure there is connectivity between the mobile phone and the raspberry pi. You can confirm it by pinging your mobile phone from your Raspberry Pi by pinging to your mobile phone
ping <ip address of mobile phone>
Take a note of the IP address of the raspberry Pi as we will be using it in the future.
Step 4 – Connections
Raspberry Pi should be provided with 5V.
For this project we will be using 4 GPIO pins to control the devices. 11, 13, 15 and 29 all goes directly to the 4 relays input.
Step 5 – Setting Up the Listener
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Now all you have to do is setup a listener on the Pi. Download the sketch from the link below and save it as a file named “automation.py”
Run the script by running
Step 6 – Install RootSaid WiFi Command Center from Google PlayStore
RootSaid WiFi Command Center
is a simple light weight android application that can be used to control robots and home appliances over WiFi. All you have to do is connect your mobile phone to the network, enter the IP address and Port of the server (the home automation system) and control it using the On Off buttons. Click here to know more about this App.
to Download this app from Playstore.
Now all you have to do is start the App, enter the IP address of the Pi and port it is listening to (5050).
Load the IP and Port using the link button and navigate to the Home Automation Tab.
Thats it, you can now control devices connected to your raspberry pi using this simple app and turn it on and off.
Coming Soon – Controlling It from Outside the LAN over the Internet. Subscribe to RootSaid to get live updates.
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