Master and Slave two way Bluetooth Data Communication

This project demonstrates the communication between two Bluetooth HC-05 modules. Here One Bluetooth module configures as master and the other is the slave.

This project is built using Arduino UNO, servo, DHT11 sensor, LCD, LDR sensor, HC-05, and switch on the master side, whereas on the slave side Arduino UNO, LCD, 10K ohm variable pot, and HC-05 module is used. 

The project works in the following manner: 

• After turning ON both the system, Bluetooth modules automatically get connected, because the Master is configured to connect with a predefined Bluetooth module with the address.
• After successful connection data from the master starts displaying on the slave LCD.
• The user needs to turn the variable resistor and the servo movement and be seen on the master side.

Same at the master side a switch is there to turn ON the LED on the slave side.

Hardware Requirements:

MASTER SIDE:

• 👉  Small Bread Board
• 👉  Arduino UNO
• 👉  I2C LCD Module
• 👉  16x2 LCD Module
• 👉  HC-05 Bluetooth module
• 👉  Micro servo
• 👉  DHT11 sensor
• 👉  LDR sensor
• 👉  LDR sensor module
• 👉  Microswitch
• 👉  Variety of connectors

SLAVE SIDE:

• 👉  Small Bread Board
• 👉  Arduino UNO
• 👉  I2C LCD Module
• 👉  16x2 LCD Module
• 👉  HC-05 Bluetooth module
• 👉  5mm LED
• 👉  Variable Resister POT 10K
• 👉  Variety of connectors

Software Requirements:

• Arduino IDE (You can download it from HERE).
• Arduino DHT Library (Download it from HERE).
• Arduino I2C LCD Library (Download it from HERE).
• Wire Library (Inbuilt within the IDE).
• Servo Library (Inbuilt within the IDE).

Configure HC-05 as master and slave using AT-COMMANDS

Follow the above circuit diagram and provide the below AT-COMMANDS one after another to convert as MASTER or SLAVE.

SLAVE:

STEP1: AT to check the module status and it will respond with OK.

STEP2: AT+ROLE? is to get the module role if it responds with '0' it is in SLAVE mode and if it is '1' then it is in MASTER mode. After checking if it is '0' then no need to change anything. But if it responds with '1' then again provide AT+ROLE=0 in the serial terminal to change the module to SLAVE mode.

STEP3: AT+ADDR? the command is to get the address of the module. (mine 21:13:5B50) DONE!

 

MASTER:

STEP1: AT to check the module status and it will respond with OK.

STEP2: AT+ROLE? is to get the module role if it responds with '0' it is in SLAVE mode and if it is '1' then it is in MASTER mode. After checking if it is '1' then no need to change anything. But if it responds with '0' then again provide AT+ROLE=1 in the serial terminal to change the module to MASTER mode.

STEP3: AT+CMODE=1 this command is provided to fix the address of the slave. And whenever the slave and master turned ON the master will automatically get connected with the slave's address.

STEP4: AT+BIND=21,13,5B50 this command will bind with the slave address. As you can see my Bluetooth address is 21:13:5B50 but we have provided a comma-separated. So, you need to follow the same procedure to work properly. DONE!

Testing: Now just turn on both the modules, and you will see the master will connect automatically to the slave by changing the LED blinking frequency. It increases the time delay between the blinks.

SLAVE Circuit diagram:

 

Connection of I2C LCD with Arduino:

I2C LCD Module	Arduino UNO
Vcc	5v
GRND	GRND
SDA	A4 (SDA)
SCL	A5 (SCL)

 

 

MASTER Circuit diagram:

Connection of DHT11 with Arduino:

DHT11	Arduino UNO
PIN1 (Vcc)	5v
PIN2 (OUT)	A0
PIN3	NC
PIN4 (GND)	GND

 

Connection of I2C LCD with Arduino:

I2C LCD Module	Arduino UNO
Vcc	5v
GRND	GRND
SDA	A4 (SDA)
SCL	A5 (SCL)

 

Master source code: Download here 

Slave source code: Download here

 

Video tutorial: