Home. » Project 1: Serial communication with Bluetooth HC-05 FC-114.


bluetooth Module HC-05.


What you will need:


  • Bluetooth module HC-05 FC-114.
  • Arduino UNO board (or any Arduino board is suitable).
  • Arduino Software (IDE). Download from https://www.arduino.cc/en/Main/Software (Windows ZIP file for non admin install).
  • PC or Laptop with on board a bluetooth module or external USB bluetooth dongle.  Operating systeem, that is suitable for this project, is Windows XP/VISTA/7/8/10
  • Hyperterminal or other serial communication programs. You may also use the "serial monitor" provided by the Arduino Software (IDE), because from version Windows Vista hyperterminal is not included anymore.
  • Serial to USB converter module FTDI232 with I/O voltage levels 3.3 Volts.
  • A breadboard and some wires with dupont-connectors.
  • The power supplies (3.3 and 5 Volts) can be achieved from the ARDUINO UNO board, that is fed with an external power supply adapter (minimal 7 Volts/1 Ampère, DC).


The schematic.





The devices you need.


HC-05 FC-114 module (front and back).

FTDI232 module (front and back).

Arduino UNO clone.

Bluetooth USB dongle.

Breadboard and wires.



hc-05 FC-114.


The HC-05 FC114 module has the following connections:

    . STATE (output).

This goes HIGH when the module is OPENED for active communication  to another Bluetooth module and goes LOW when when the communication is CLOSED. The STATE_LED  gives the indication that communication is OPENED and in progress.


     . RX (input).  Serial data in.

    . TX (output). Serial data out.

    . GND (input).  Negative power supply input.

    . VCC (input).  Positive power supply input (3.6 - 6 Volts).

    . EN (input).  Module is enabled and is by default HIGH.

The MODE_LED indicates 4 conditions:

  1. AT Mode   -  slow blinking (0.25Hz), this is for configuration purposes only.
  2. Trans Mode  -  fast blinking (2Hz), normal standby operation, communication CLOSED.
  3. Paired Mode  -  medium blinking (1Hz).
  4. Connection Mode  -  blinks twice and stops for long time (approx. 2s), and repeat itself,       communication OPENED.


Putting the HC-05 module in AT Mode:

When the module is powered up, while HOLDING DOWN the PUSH_BUTTON and after that released the module goes in AT Mode. MODE_LED indicates slow blinking. The default communication parameters are 38400, 8, N, 1,  no handshaking.

The supply voltage (3.6 - 6 Volts) is higher than 3.3 Volts. It means that the sub-module is fed with a voltage regulator of 3.3 Volts. So the I/O voltage levels are therefore 3.3 Volts.




The FTDI232 module is a serial to USB converter. So the module works in principle on 5 Volts from the USB connector. On board of the FTDI232 there is a jumper to select for I/O voltage levels for 3.3 and 5 Volts. This module is connected by an USB cable to the PC/laptop. A serial communication  program like HYPERTERMINAL on the PC/laptop is used to communicate with the FTDI232. You may use other communication programs as well.


Used connections and jumper on the FTDI232 module:

     . RX (input), with 3.3V voltage level.

     . TX (output), with 3.3V voltage level.

     . GND (input).

     . JUMPER, this must be set to 3.3V.




configuring and testing the HC-05 module.


The first step we have to do is to configure the HC-05 by setting this module into the "AT Mode".  After this configuration the Bluetooth module HC-05 acts as a slave, recognized by its PASSWORD and is ready to connect with the other Bleutooth module running on your PC/laptop.


The following document describes the configuration and testing.