Overview of Bluetooth

HC-05 is a Bluetooth device used for wireless communication with Bluetooth enabled devices (like smartphone). It communicates with microcontrollers using serial communication (USART).

Default settings of HC-05 Bluetooth module can be changed using certain AT commands.

As HC-05 Bluetooth module has 3.3 V level for RX/TX and microcontroller can detect 3.3 V level, so, there is no need to shift TX voltage level of HC-05 module. But we need to shift the transmit voltage level from microcontroller to RX of HC-05 module.

For more information about HC-05 Bluetooth module and how to use it, refer the topic HC-05 Bluetooth module in the sensors and modules section.

Connection Diagram of HC-05 with Arduino

Note : Default Bluetooth name of the device is “HC-05” and default PIN (password) for connection is either “0000” or “1234”. 

Send Message using Bluetooth HC-05 With Arduino

Here, we will transmit data from Smartphone via Bluetooth to the Arduino Uno and display it on Serial Monitor of PC.

Download and install a Bluetooth terminal application on your phone and use it to connect to the HC-05 Bluetooth module.

Data is sent from the Smartphone using the Bluetooth terminal application.

HC-05 Bluetooth Module Code for Arduino Uno

#include<SoftwareSerial.h>

/* Create object named bt of the class SoftwareSerial */ 
SoftwareSerial bt(2,3); /* (Rx,Tx) */	

void setup() {
  bt.begin(9600);	/* Define baud rate for software serial communication */
  Serial.begin(9600);	/* Define baud rate for serial communication */
}

void loop() {
  
    if (bt.available())	/* If data is available on serial port */
    {
     Serial.write(bt.read());	/* Print character received on to the serial monitor */
    }
}

Video of HC-05 Bluetooth Communication With Arduino Uno