Change the baud rate of HC-05 Bluetooth module
In order to connect a HC-05 Bluetooth module to your flight controller, you should probably change the standard baud rate of the module. I will show you how to do this with your Arduino board. You can also change the password or name of the module.
There are different HC-05 modules, but it works with all of them. On the picture you can see a bare HC-05 module, a 5V HC-05 module and a 6V HC-05 module with a button. I prefer the last one, as the button makes changing the settings easier.
To change any settings, the module should be in “AT Mode”. To do this, the “Key Pin” of the module should be set to “High”. This means you need to apply voltage to this pin at the same time you power the module.
On the 6V HC-05 module, the button does this job. Just press it while powering the module with 5V. On the module without button, you need to supply 3.3V to the “Key Pin” while powering on.
How to connect:
First connect the Arduino to the PC over USB. Then connect the cables in the following way:
TX Bluetooth –> TX Arduino
RX Bluetooth –> RX Arduino
GND Bluetooth –> GND Arduino
… and at last the 5V Bluetooth to 5V Arduino by keeping the button of the Bluetooth pressed. Or on the module without a button, connect the “Key Pin” to 3.3V on Arduino. Note: bridge the GND and RST pins with a jumper. The Arduino should have a FTDI chip on it.
If the HC-05 is in AT Mode, the red LED will blink at every 2 seconds. Then start the PuTTY program, configure the right COM Port (check it in the Device Manger) and set the Baud Rate to 38400. This is the baud rate for AT Mode. Then click “Open”.
In the newly opened window type “AT”, press “Enter” and you should get “OK” as a result. Here some of the commands to change the settings you wish:
|Change baud rate to 57600, 1 stop bit, 0 parity:||AT+UART=57600,1,0|
|Change module name:||AT+NAME=YOURNAME|
|Change pairing code:||AT+PSWD=0000|