Bulb-Control-By-Arduino-and-Mobile

Download the app

Arduino Code

Implementing a system where we can automatically switch on or off any two appliances through a mobile device using Arduino Uno and Bluetooth module.

COMPONENTS REQUIRED:

1. Arduino Uno
2. Bluetooth Module HC-05
3. 2 channel Relay
4. Breadboard
5. 2 Bulbs
6. Wires
7. A Bluetooth Control App

ARDUINO UNO

It can be powered by a USB cable or by an external 9 volt battery, though it accepts voltages between 7 and 20 volts. It is also similar to the Arduino Nano and Leonardo. The hardware reference design is distributed under a Creative Commons Attribution Share-Alike 2.5license and is available on the Arduino website. Layout and production files for some versions of the hardware are also available.

BLUETOOTH MODULE

HC‐05 module is an easy to use Bluetooth SPP (Serial Port Protocol) module, designed for transparent wireless serial connection setup. The HC-05 Bluetooth Module can be used in a Master or Slave configuration, making it a great solution for wireless communication. This serial port Bluetooth module is fully qualified Bluetooth V2.0+EDR (Enhanced Data Rate)3Mbps Modulation with complete 2.4GHz radio transceiver and baseband. It uses CSR Bluecore 04‐External single chip Bluetooth system with CMOS technology and with AFH (Adaptive Frequency Hopping Feature).

The HC-05 has two operating modes, one is the Data mode in which it can send and receive data from other Bluetooth devices and the other is the AT Command mode where the default device settings can be changed. We can operate the device in either of these two modes by using the key pin as explained in the pin description.

RELAY

The Arduino Relay module allows a wide range of microcontroller such as Arduino, AVR, PIC, ARM with digital outputs to control larger loads and devices like AC or DC Motors, electromagnets, solenoids, and incandescent light bulbs. This module is designed to be integrated with 2 relays that it is capable of control 2 relays.The relay shield use one QIANJI JQC-3F high-quality relay with rated load 7A/240VAC,10A/125VAC,10A/28VDC.The relay output state is individually indicated by a light-emitting diode.

The relay has two outputs-normally open and normally closed (NO and NC). When the IN1 or IN2 pin is connected to ground, NO will be open and NC will be closed, and when IN1 or IN2 is not connected to ground the opposite occurs. Connecting a circuit or device between one of these two pins, the common pin on the relay output, and a power source will allow you to toggle power to a circuit or device.

BLUETOOTH CONTROLLING APP

The other part of the project consists of developing an Android app that can send messages to the Bluetooth module which the module uses to perform its actions. The app sends following signals:

• To make the bulb on, app send an “ON” signal by the press of Bulb icon.
• To make the bulb off, app send an “OFF” signal by the press of Bulb icon.
• Checking any checkbox for the bulb send “1” and “2” for bulbs 1 and 2 respectively, which is used to enable the bulbs.
• Unchecking any checkbox for the bulb send “01” and “02” for bulbs 1 and 2 respectively, which is used to disable the bulbs.
• To send a signal to turn off the device after a fixed time, the data sent has the following format. Number following b is the start delay. Number following e is time after which bulb will turn off.

bxxx000exxx000

where xxx represents integer of any arbitrary length.

The app consists of following two screens, which in terms of app development are known as activities:

The first screen shows the devices which are paired with the mobile phone. In above screenshot, the device named arghya is our Bluetooth module. The devices show up on pressing the SHOW PAIRED DEVICES button at the bottom of the screen. Initially the list remains empty.

The second screen is the screen which is used to control the bulbs. This screen will show up only if the app is connected to a Bluetooth module. This is the case because the app actually uses the UUID (Unique Universal Identifier) to connect with the module. If it is not able to find a device with the specified ID, which is hardcoded in the app, it won’t be able to connect.

At the top of the second screen, we see two checkboxes labeled as Bulb 1 and Bulb 2. At any time, only those bulbs use to glow which have been checked in the app. How we can achieve this can be understood by seeing the Arduino code and the messages sent by the app as described above.

Below it is a big bulb icon. On clicking it, we can turn on the bulb if it is off, and turn it off if it is on. When the actual bulb turns on, the bulb icon in the app, which is depicting a off bulb changes into a glowing bulb, as shown in the screenshot.

Below it are two edit text fields, which are prompting to enter seconds. They are marked as Start Delay and Stop After. Start delay means the number of seconds after which the bulb should start glowing. Stop after means the number of seconds after which the bulb should stop glowing once it had started glowing.

On sending any message by pressing the bulb icon, or by checking or unchecking any checkbox, a short message, known as toast in the Android terminology, shows up at the bottom side of the app.

At the bottom of this screen, there is a disconnect button, which is used to break the connection from the Bluetooth module. Pressing this button also sends a “STOP” signal, which is then used by the Arduino code to reset the two variables which are used to glow the bulbs by containing the pin numbers. This helps so that the bulb goes off if the Bluetooth is not connected.

CIRCUIT:

The necessary circuit for the project can be built up with the help of the following diagram. The diagram shows connection of a single relay. It can be extended to two bulbs using a 2 channel relay.

To make the proper circuit for the connections, follow the given instructions:

1. Provide Vcc and ground to the relay, either by taking two wires directly from the Arduino, or by using a breadboard.
2. Connect one end of the wire connected to the bulb to the relay’s NC part, and connect the other part, labelled as COM to the power supply directly. Repeat the same process with the other bulb. As we are using a two-channel relay, the Vcc and ground will be the same for both the relays.
3. Connect the other wires coming out of both the bulbs to the main power supply.
4. Take two wires from digital pins 2 and 3 of the Arduino and connect them with the input pins 1 and 2 of relay. The pins 2 and 3 are the output pins.
5. To connect the Bluetooth module, connect the Vcc and GND pins of Bluetooth module with the Vcc and GND pins of Arduino.
6. Connect the TX and RX pins of the Bluetooth module with the pins 10 and 11 of the Bluetooth module, as the pins 10 and 11 of the Arduino board have been defined as the RX and TX pins.

WORKING:

Follow the following steps to use the model:

1. Give power to the Arduino board by connecting it with any 5V power source either by using the cable provided with the board.
2. The Bluetooth module LED will start blinking rapidly, which indicates that the Bluetooth module is ready to accept a connection, but is not yet connected.
3. Now open the Android app and press the SHOW PAIRED DEVICES button at the bottom of the screen. If the Bluetooth module is already paired up, it will show up there. If it doesn’t show up, go to the Bluetooth options in the settings of your Android phone and scan for the Bluetooth module and pair the mobile phone with it.
4. Now, if you will click on the name of the Bluetooth module from the app, you will be taken to the next screen, from where you will be able to control the bulbs. The controlling process has already been described in the app section.

CONCLUSION:

Thus, finally we can see how using a prebuilt technology in our mobile phones, i.e., Bluetooth, we are able to control electrical appliances if our home. The technology can find numerous uses in the daily life.

The delay functionality included in the app can be a bonus. One of its uses can be as a reminder, where let’s say if someone has decided that he or she wants to study after 30 minutes, then he can enter the start delay as 1800 (30 minutes = 30x60 seconds). Thus the light, which can be the study lamp, will turn on after 30 minutes, thus reminding that it’s the time to study.

Moreover, the limitation of range, that exists because of the Bluetooth technology, can be removed by using a Wi-Fi module.