Bluetooth AT Commands (How to Configure and pair two Bluetooth as Master and Slave Mode)

Overview

In this tutorial, we will learn how to configure an HC-05 Bluetooth module as Master and Slave. We will also learn how to pair or communicate between two Bluetooth module. 

You can watch the following video below:-

Components Required

The required components list for this project given below:-

• Arduino Uno
• Arduino Nano
• Two HC-05 Bluetooth Module 
• 2.2K ohm Resistor
• 1K ohm Resistor
• 2 Push Button
• 2 LED
• Breadboard
• Some Jumper Wire

Pinout

Circuit Schematic

Source Code

The slave source code is given below:-

 //*******************Slave*****************  
   
 #define buttonPin 8  
 #define ledPin 7  
   
 int state = 0;  
 int buttonPinState = 0;  
   
 void setup() {  
  pinMode(buttonPin, INPUT);  
  pinMode(ledPin, OUTPUT);  
  digitalWrite(ledPin, LOW);  
  Serial.begin(9600);   
 }  
 void loop() {  
  if (Serial.available() > 0) {  
   state = Serial.read(); // Reads the data from the serial port  
  }  
   
  // data receiving part  
  if (state == '1')  
  {  
   digitalWrite(ledPin, HIGH); // led turn on  
  }  
  else if (state == '0')  
  {  
   digitalWrite(ledPin, LOW); // led turn of  
  }  
   
  // Data sending Part  
  buttonPinState = digitalRead(buttonPin);  
  if (buttonPinState == HIGH) {  
   Serial.write('1'); // Sends '1' to the master to turn on LED  
  }  
  else {  
   Serial.write('0');  
  }  
 }  

The master source code is given below:-

 //***************Master*******************  
   
 #define buttonPin 4  
 #define ledPin 5  
   
 int state = 0;  
 int buttonPinState = 0;  
   
 void setup() {  
  pinMode(ledPin, OUTPUT);  
  digitalWrite(ledPin, LOW);  
  pinMode(buttonPin, INPUT);  
  Serial.begin(9600);   
 }  
 void loop() {  
  if (Serial.available() > 0) {   
   state = Serial.read(); // Reads the data from the serial port  
  }  
    
   if (state == '1')  
  {  
   digitalWrite(ledPin, HIGH); // led turn on  
  }  
  else if (state == '0')  
  {  
   digitalWrite(ledPin, LOW); // led turn of  
  }  
    
  // Data sending Part  
  buttonPinState = digitalRead(buttonPin);  
  if (buttonPinState == HIGH) {  
   Serial.write('1'); // Sends '1' to the slave to turn on LED  
  }  
  else {  
   Serial.write('0');  
  }  
 }