AT command mode of Bluetooth module HC-05.

AT Command Mode

• AT command mode is used to change settings of the Bluetooth module HC-05.
• To operate the module into AT command mode you have to give High to the "Key/EN" pin.
• To do this you have to connect the Bluetooth module to a PC using serial to USB converter and give the commands through serial terminal of the PC.
• Now the default Baud rate of the module is 38400 in AT command mode.
• Some of the settings that you can change through the command mode are like changing the password, baud rate, device's name, get the version and also reset to default settings, etc. 
• Following are some of the AT commands and their description:-

HC-05 Bluetooth Module

AT Commands

1. AT:- Used to Check the connection.
2. At+NAME:- To see the default name.
3. AT+ADDR:- To see the default address
4. AT+VERSION:- To see the version of the module.
5. AT+UART:- To see the set baud rate of the module.
6. AT+ROLE:- To see the role of the module i.e it is master=1 or slave=0.
7. AT+RESET :- To reset and exit AT mode.
8. AT+ORGL:- Restore the factory settings.
9. AT+PSWD:- To see default password.