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

Leave a Reply


    • Sergey

      Hey, is your Nano v3 with a FTDI chip on it? Didnt have any problems, just connected the all the 4 cables and it was fine… Best, Sergey

      • sl1pkn07

        have CH341 chip (both units). this not work with this chip?

      • sl1pkn07

        tested with a genuine Arduino Uno

        works ok (?¿)



        • Sergey

          It should be because of the FTDI chip, which inverts the serial signal. So now everything is fine, right?

          • sl1pkn07

            whit the arduino uno is OK, but with the nano (invert or not the TX/RX) no :/

          • Sergey

            Well, maybe it is because of the CH341 chip. I havent had that one, so I cant say for sure.

  1. TX Bluetooth –> TX Arduino
    RX Bluetooth –> RX Arduino looks suspicious for me.

    Shouldn’t you connect the transmit of the Bluetooth module to the receive of the Arduino?

    TX Bluetooth –> RX Arduino
    RX Bluetooth –> TX Arduino

    • Sergey

      In general yes, but because of the FTDI adapter (where TX and RX are reversed) I needed to connect it that way.

  2. Pingback: HOW TO? HC-05 AT Commands - Arduino Sensors