Module Bluetooth

Introduction

I bought this bluetooth module (HC-05 or BT400_B6) on ebay some weeks ago at very low price.

I decided to test it with an Android telephone.

This module is configured as Slave by default.

Required Components

• Bluetooth HC-05
• Android App Terminal Multi (Google Play Download)

Product Specifications

• Chipset CSR BC417143
• Bluetooth version V2.0+EDR
• Output power Class II
• Flash 8Mbit
• Power Supply 3.3V
• Size 26.9mm*13mm*2.2mm

Pin Description

Connectivity

HC05 pin	Mbed pin
1 - Tx	P10 - Rx
2 - Rx	P9 - Tx
12 - 3.3V	Vout - 3.3V
13 - GND	GND
31 - PIO8	--
32 - PIO9	--
34 - PIO11	GND or 3.3V

PIO8 is used to control LED indicating the status. It will blink after power on.

PIO9 is used to control LED indicating paring. It will be steady on when paring is successful.

PIO11 is used to set this two mode: AT command mode (if the pin is connect to 3.3V) or Automatic binding transparent data mode (if the pin is connect to GND). The AT command mode is used to configure some characteristics of the device (for example the Master, Slave or Loopback modes).

Code for Transparent data mode

Example: Bluetooth communication between Pc and Android Phone

First you must turn on the Bluetooth on your Android phone.
Search the bluetooth device and pair with it (the password is 1234).

Then open "Terminal Multi" and press the button "SEARCH" for select the paired device (HC-05).
In the end press "CONNECT".

Bluetooth Settings

Output example

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AT command mode

In AT command mode you can configure and send control command to the HC05 device.

For enter into AT mode you must follow this steps:

• Power off the mbed
• Tie PIO11 to 3.3V (you can see it on the schematic below)
• Power on the mbed
• Open a serial monitor (Set the baud to 115200; choose "Both CR+LF" in the check box)

Schematic for AT command mode

Basic AT commands

Command	Return	Parameter	Description
AT	OK	None	Test
AT+VERSION?	+VERSION:<Param> OK	Param: Version number	Get the soft version
AT+ORGL	OK	None	Restore default status
AT+ADDR?	+ADDR: <Param> OK	Param: Bluetooth address	Get module Bluetooth address
AT+NAME=<Param>	OK	Param: Bluetooth device name	Set device’s name
AT+NAME?	+NAME:<Param> OK	Param: Bluetooth device name	Inquire device’s name
AT+ROLE=<Param>	OK	Param:0=Slave role; 1=Master role; 2=Slave-Loop role	Set module role
AT+ ROLE?	+ ROLE:<Param>	Param:0=Slave role; 1=Master role; 2=Slave-Loop role	Inquire module role
AT+UART=<Param>,<Param2>,<Param3>	OK	Param1: baud rate( bits/s); Param2: stop bit; Param3: parity bit	Set serial parameter
AT+ UART?	+UART=<Param>,<Param2>,<Param3> OK	Param1: baud rate( bits/s); Param2: stop bit; Param3: parity bit	Inquire serial parameter

Is possible to set this three modes:

• Slave: Passive connection;
• Master: Inquire the near SPP Bluetooth slave device, build connection with it positively, and build up the transparent data transmission between master and slave device;
• Slave-Loop: Passive connection, receive the remote Bluetooth master device data and send it back to the master device.

Code for AT command mode

Important: The default setting of the serial port of HC05 is: baud 38400; 1stop bit and no parity.

Output for AT command mode

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C# Test Program

You can download the program here: HC05 Test Software v1.2
Is required Microsoft .NET Framework 4.0 or above.

Screen:

Select the correct COM Port and the BaudRate and press the "Connect" Button.

UPDATE:

U3: Added new Android Application (Terminal Multi)
U2: Updated HC05 Test Software and added new screens
U1: Updated the HC05 Test Software