HC-05 BLUETOOTH MODULE

 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 HC05 Bluetooth module in the sensors and modules section.


HC-05 Pin Description

  • EN: It is the enable pin. When this pin is floating or connected to 3.3V, the module is enabled. If this pin is connected to GND, the module is disabled.
  • +5V: This is the supply pin for connecting +5V. As the Module has on-board 3.3V regulator, you can provide +5V supply.
  • GND: It is the ground pin.
  • TX: It is the Transmitter pin of the UART Communication.
  • RX: It is the Receive Pin of UART.
  • STATE: This is a status indicator pin. This pin goes LOW when the module is not connected to any device. When the module is paired with any device, this pin goes HIGH.

NOTE: The on-board LED is used to indicate the status of the connection. When the module is not paired, the LED blinks or flashes repeatedly. Once the module is paired, the LED blinks at a constant delay of 2 seconds.

Modes of Operation

The HC-05 Bluetooth Module can be configured in two modes of operation: Command Mode and Data Mode.

In Command Mode, you can communicate with the Bluetooth module through AT Commands for configuring various settings and parameters of the Module like get the firmware information, change UART Baud Rate, change module name, set it as either Master or slave etc.  

An important point about HC-05 Module is that it can be configured as Master or Slave in a communication pair. In order to select either of the modes, you need to activate the Command Mode and sent appropriate AT Commands.

Coming to the Data Mode, in this mode, the module is used for communicating with other Bluetooth device i.e. data transfer happens in this mode.

Default Settings of HC-05 Bluetooth Module

The following is a list of few of the default settings of the HC-05 Bluetooth Module.

  • Name: HC-05
  • Password: 1234 (or 0000)
  • Type: Slave
  • Mode: Data
  • Baud Rate: 9600 with 8 data bits, no parity and 1 stop bit

Circuit Diagram



CODING:

#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 */ } }


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