Bluetooth Module Interfacing using HC05 Module and Wireless Communication

Bluetooth modules are used for short distance and point-to-point wireless data transmission and reception. The range of distance varies from module to module depending on the version of the module being used. For DIY projects, these are available as breadboard friendly modules. Even though these modules (hobby purpose modules) do not provide access to all those pins in the actual module (For Ex:- the GPIO pins ) provided by the manufacturer, these are fairly enough for wireless communication. In this article lets learn more about Bluetooth Module (HC 05 Bluetooth module) and how to interface a Bluetooth module to Personal/Desktop Computer (PC) via USB. The HC-03 and HC-05 modules are similar to each other, whereas the HC-04/HC-06 modules are different from the HC-05 module. The difference lies in the option to select the role of operation of the module. The HC-05 module can be operated in the Slave role as well as the Master role. The user can send appropriate commands to select the role of operation. The role of operation of the HC-06 or the HC-04 module is preset by the manufacturer as factory settings. They operate either in the Master role or the Slave role. The User cannot select the role of operation for the HC-04/HC-06 modules after purchasing. The user should verify which operation mode the module is configured (master or slave) before purchasing. Pin Configuration of the HC-05 Bluetooth module: The Data transmission is based on the UART serial communication protocol through the UART pins of the module at 3.3 or 5 Volts TTL level. Typically, a blue tooth module contains the pins namely, Working with the HC-05 Bluetooth Module: Initially, to learn how to interface the UART Based modules, it is better to use a Hyper Terminal software. By connecting the Bluetooth module to USB-Serial converter, the data can be sent to the module and data received by the module can be read through the software. Many of the microcontroller Programming software’s contain the hyper terminal feature. Otherwise, there are third party hyper terminal Softwares. Download the Hyper Terminal Software (Windows) Using the Hyper Terminal Software: In order to start communication with the module, the Serial Port should be configured. The Physical port number of the USB-Serial converter is obtained from the devices and printers under control panel. In the software, under set-up menu, select ‘port configuration’.   In the Port Configuration window, select the port of the USB-Serial converter, Baud rate of 38400, remaining parameters are generally the same by default. Click on the Connect button. After successful connection to the port, the status is displayed at the bottom of the software.     Every ‘AT’ command should end with \r\n. There is an option within the hyper terminal software to send Carriage Return ‘\r’ and Line Feed ‘\n’ characters as CR+LF. By enabling this option, these characters are sent after every command by default. The command to be sent is typed in the command box. By clicking on the Send button, the command is sent through the configured port.   AT Command Mode: When the Key pin of the module is left open or connected to GND and the module is powered ON, the module operates according to the settings made during the previous usage. To know the role of operation or the name/address of the device and some other details, it is necessary to enter into the AT Command mode. Most of the modules have a push button with the pin name of ‘EN’, in place of the KEY pin. Connect the Key/EN pin to +Vcc and power ON the module. Now,...
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