Posts with «bluetooth module» label

How to enter AT mode in HC-05 bluetooth module

Using HC-05 in AT mode

Hello guys, In this post we will cover how to change password, name or mode (master or slave) in HC-05 module. 

Things required:

1. Arduino Uno board
2. Jumper wires
3. HC-05
4. Little bit patience :p

Note: Use can USB-TTL instead of arduino uno board. In this case, arduino uno board is simply used as USB-TTL converter.

Steps to follow:

First of all, upload a blank program to arduino.

/* Arduino Program */

void  setup(){


void  loop(){


Connections should be a follows:

Arduino                              HC-05
TX              ====>             TX
RX              ====>             RX
VCC            ====>             VCC
GND           ====>              GND

Note: Before powering up the arduino, the button should be pressed and it should be released after some time after powering up the arduino.  

If there is no switch on your module,  you have to apply 3.3 volt to pin number 34 of HC-05 before power up. After power remove the 3.3 volt.

Now, if the HC-05 in at mode led will blink after every 2 seconds.

After connection, open serial monitor. The baud rate should be selected to 38400 and both nl and cr should be selected.

After this, you have to pass AT commands:

AT and press enter
The response is OK

AT+ROLE? and press enter
The response is 0 or 1
0- Slave
1- Master

AT+UART? and press enter
The response is Baud rate

AT+PSWD? and press enter
The response is 1234    // it's your password.

For changing the password, command is AT+PSWD=1587  
This commannd will set the password to 1587.

Check out the video:

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