To setup Wireless Serial Communication, HC-05 Bluetooth Module is most demanding and popular due to its low price and extremely high features.

This module can be used in Master or Slave Mode and easy switchable between these two modes, By default Slave mode is configured.

Modes can be changed using AT Commands.

The slave mode in HC-05 cannot initiate a connection to another Bluetooth device but can accept connections. Master mode can initiate a connection to other devices.

HC-05 Specifications:- 

• Profiles: Bluetooth serial port Profile
  
• Bluetooth protocol: Bluetooth Specification v2.0+EDR
  
• Frequency: 2.4GHz ISM band
  
• Modulation: GFSK(Gaussian Frequency Shift Keying)
  
• Emission power: ≤4dBm, Class 2
  
• Sensitivity: ≤-84dBm at 0.1% BER
  
• Speed: Asynchronous: 2.1Mbps(Max) / 160 kbps, Synchronous: 1Mbps/1Mbps
  
• Security: Authentication and encryption
• Power supply: +3.3VDC 50mA
  
• Working temperature: -20 ~ +75Centigrade
  
• Dimension: 26.9mm x 13mm x 2.2 mm