Connecting and Configuring HC-05 Bluetooth Module

Power and connect the bluetooth module to a serial connection on your computer.  My connections using an FTDI TTL-232R-3V3 cable are:

HC-05	TTL-232R-3V3
VCC	VCC (Red)
GND	GND (Black)
RXD	TXD (Orange)
TXD	RXD (Yellow)

Remember the logic levels of the HC-05 are not natively 5v tolerant so a level converter should be used to avoid letting out the magic smoke.  My cable uses 3V3 logic so a converter is not needed.

Voltage Notation

As an aside I have for a long time followed the convention of putting the V for voltage where the decimal place would go.  I find this quickly and clearly communicates the voltage where a decimal point could be missed, or smudged, since I grew up when CAD was relatively new and expensive and drawings were completed by hand.  I understand this could be confusing to someone and hence this quick explanation.

Voltage	Equivilent
2.5V	2V5
3.3V	3V3
5V or 5.0V	5V
12V	12V

Configuration

Now the connections have been made the LED on the HC-05 should be blinking.  If this is a short blink every two seconds then it is likely you are in AT Command mode, but otherwise AT commands will not work.   This indicates

Commands are case sensitive.

38400-8-N-1
EOL (End of Line): Both NL and CR

AT commands take a similar form to read and write parameters.  The difference is to write a parameter append =NewParamterValue after the AT command.  For example:

Read Parameter	Write Parameter
AT+NAME	AT+NAME=NewName

Where NewName is the new name of the module.

Read/Write PIN Code

AT+PSWD

Check firmware version

AT+VERSION

Check module mode
AT+ROLE
0 Slave
1 Master
2 Slave loopback




AT Command List
AT+RESET will exit AT mode.

Establishing A Bluetooth Connection 

The bluetooth module appears as JDY-30 when adding a bluetooth device to your system.  The default pairing code is: 1234.  Drivers will be installed to create a virtual serial port for the connection.