How To Configure The Bluetooth HC-06 Module With AT Commands ...

How to configure the Bluetooth HC-06 module with AT commands, using Bolt 18F2550 system, through the serial port.

Background:

In a previous project described here, an expansion card with a Bluetooth module HC-06 and a serial interface RS232- DB9 connector was developed. The card is inserted into the serial port of any microcontroller system.

The company sells a product based on this design: Bluetooth HC-06 module with serial port

Description:

In the particular case of this project, the Bolt 18F2550 system was used, as shown in the following photos, to transmit the AT commands, through the serial port of the HC-06 Bluetooth module.

It is important to note that the 5 volt @40 ma. supply needed for the Bluetooth expansion module shown below, is fed from the Bolt board through the pin 7 of the DB9 connector.

3 different programs were developed in ANSI C to test each of the AT commands, as shown in the table below.

To test each of the AT commands, connect devices as shown in photos below.

PCB VERSION OF BLUETOOTH MODULE WITH SERIAL PORT:

SYSTEM TO CONFIGURE HC-06 MODULE WITH AT COMMANDS:

AT COMMANDS FORMAT:

All AT commands are strings of ASCII codes. According to the manufacturer's specification, the entire command (without enter CR/LF), should be transmitted from the microcontroller board to the HC-06 Bluetooth in a single time, at 9600 bps (which is the default rate).

For this purpose, using the Bolt 18F2550 system, three ANSI C programs were developed to send some of the commands, and display the responses of the HC-06 module in the system LCD.

AT COMMANDS TESTING:

To do testing of the commands, you have to load the corresponding .hex file to the Bolt system and see the response in the LCD, according to the table below. You may also modify the .c source file according to your needs, to change the parameters.

**In this particular command, the user will see the new name only when pairing the Bluetooth HC-06 device to a PC computer with a master Bluetooth module as shown below for a Windows 8 machine. In this example, name was modified to "BlueBolt".

-For a preliminary testing of AT commands. Command: 'AT' Response: OK Use the following program: C18-BOLT-BLUETOOTH-AT.zip

-To obtain the firmware version of HC-06. Command: 'AT+VERSION' Response: OKLinvorV1.8 Use the following program: C18-BOLT-BLUETOOTH-VERSION.zip

-To change the device name. Command: 'AT+NAMEBlueBolt' Response: OKsetname This example program changes the name of the HC-06 module to "BlueBolt". Use the following program: C18-BOLT-BLUETOOTH-BLUEBOLT.zip User may use another name modifying the .c program, compiling and loading the resulting .hex file to Bolt system.

-To change the baud rate: AT+BAUD4 (the default value is 9600).

-To change the password (pin number) for pairing: AT+PIN1234 (default is 1234).

Please note that, as factory settings, the module has a configuration of 9600 bps, pin = 1234 and name = HC-06 (some models have 'Linvor' as factory name)

Summary of AT Commands:

• Ping Test

  • No action is taken by the Bluetooth, it simply acknowledges with “OK” letting you know communication was successful.

  • Send: AT

  • Response: OK

• Set Baud Rate

  • Sets the Bluetooth UART baud rate. Baud rate is set by an hexadecimal index from '1' to 'C'.

  • Indexes are: 1:1200, 2:2400, 3:4800, 4:9600, 5:19200, 6:38400, 7:57600, 8:115200, 9:230400, A:460800, B:921600, C:1382400

  • Send: AT+BAUD<index>

  • Response: OK<baud rate>

• Set Bluetooth Device Name

  • Sets Bluetooth Device Name

  • Send: AT+NAME<device name>

  • Response: OKsetname

• Set Bluetooth PIN Code

  • Sets the security code needed to connect to the device.

  • Send: AT+PIN<4 digit code>

  • Response: OK<4 digit code>

• Check Firmware Revision

  • Get The Firmware Revision Number.

  • Send: AT+VERSION

  • Response: Linvor V1.8