The Bluetooth Module HC-05 can be act as Master and Slave. By default it is a master . It can also be configured to have different baud rates:9600, 19200,38400 etc. By default the baud rate is 38400. If you want to modify these settings. It can be acheived by sending AT Commands to the HC-05 Module. In order to send AT commands , you have to connect HC-05 Module to an USB-to-TTY module. If you dont have that like me and have an arduino board then you can use it for sending AT Commands. In order to achieve this, Open Arduino IDE Upload an empty sketch to the Arduino void setup() { } void loop() { } Connections: 1. Connect RX pin of Arduino to RX pin of HC-05(Not the other way:RX to TX) 2. Connect TX Pin of Arduino to TX pin of HC-05 . Don't connect power then before this, you have to switch HC-05 Module to AT Mode. It can be achieved in two modes: 1.One is to hold the switch and then apply the power to it, i.e. connecting VCC of Arduino to HC-05 VCC an