Overview of Bluetooth
HC-05 Bluetooth Module
The HC-05 is a Bluetooth module used for wireless communication with Bluetooth-enabled devices, such as smartphones. It communicates with microcontrollers via serial communication (USART).
The default settings of the HC-05 Bluetooth module can be modified using specific AT commands.
Since the HC-05 module operates at a 3.3V logic level for its RX/TX pins, and microcontrollers can detect 3.3V signals, there is no need to shift the TX voltage level from the HC-05. However, you will need to shift the transmit voltage level from the microcontroller to the RX pin of the HC-05 module.
For more information on the HC-05 Bluetooth module and its usage, refer to the “HC-05 Bluetooth Module” topic in the Sensors and Modules section.
Connection Diagram of HC-05 with Arduino
Interfacing HC-05 Bluetooth Module with Arduino UNO
Note: The default Bluetooth name of the HC-05 module is “HC-05,” and the default PIN (password) for pairing is either “0000” or “1234.”
Send Messages Using Bluetooth HC-05 with Arduino
In this setup, we will transmit data from a smartphone via Bluetooth to the Arduino Uno and display it on the PC’s Serial Monitor.
To get started, download and install a Bluetooth terminal application on your smartphone. Use this app to connect to the HC-05 Bluetooth module.
Data sent from the smartphone through the Bluetooth terminal application will be received by the Arduino and displayed on the Serial Monitor.
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 */
}
}